ECEstream: 8051 Microcontroller

8051 Circuits

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<b>8051 Projects/Circuits:</b></div>
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<ol>
<li><a href="http://www.ecestream.com/2014/11/line-follower-robot-using-8051.html">Line Follower Robot using 8051</a></li>
<li><a href="http://www.ecestream.com/2014/11/interfacing-hex-keypad-to-8051.html">Interfacing Hex Keypad to 8051</a></li>
<li><a href="http://www.ecestream.com/2014/11/interfacing-dot-matrix-led-display-to.html">Interfacing Dot Matrix LED Display to 8051</a></li>
<li><a href="http://www.ecestream.com/2014/11/delay-using-8051-timer.html">Delay Using 8051 Timer</a></li>
<li><a href="http://www.ecestream.com/2014/05/water-level-controller-using-8051.html">Water Level Controller using 8051</a></li>
<li><a href="http://www.ecestream.com/2014/05/voltmeter-using-8051-microcontroller.html">Voltmeter using 8051 Microcontroller</a></li>
<li><a href="http://www.ecestream.com/2014/05/random-number-generator-using-8051.html">Random Number Generator Using 8051</a></li>
<li><a href="http://www.ecestream.com/2014/05/object-counter-using-8051.html">Object Counter using 8051</a></li>
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<li><a href="http://www.ecestream.com/search/label/Intel%208051%20Microcontroller">8051 Tutorials</a></li>
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8051 Circuits

8051 Projects/Circuits: Line Follower Robot using 8051 Interfacing Hex Keypad to 8051 Interfacing Dot Matrix LED Display to 8051 D...

Line Follower Robot using 8051

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Line follower robots were one of the earliest automatic guided robots. They are able to follow a line marked on a contrasting background, usually a black line on a white surface or a white line on a black surface.  Usually the line follower robot works on a closed loop feedback algorithm where the feedback from the line sensor is used by the controller for correcting the path of the robot. The sensors are usually LED/LDR, LED/Photodiode or LED/Phototransistor pairs and the controller is an electronic circuit which executes the desired feedback algorithm. Gear motors are used for driving the robotic wheels.</div>
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The line follower robot presented here is designed to follow a black line on a white background. It has a pair of sensors (LED / LDR)  and works on a simple “align robot on center of the line algorithm”. Actually you does not need a microcontroller for implementing such a simple robot. A set of comparators and a motor driver circuit will happily do the job. But I am using the microcontroller  just to demonstrate the technology. Also this project serves as a platform for advanced line follower robots which works on complex algorithms. AT89S52 from Atmel is the microcontroller used here.</div>
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<b>Sensor</b></div>
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The sensor part consists of a set of  LED /  LDR pairs  for the left side and right sides. These LED / LDR pairs detect the black line on the white surface on which the robot is supposed to roam. The LDR has an inverse relationship between its resistance and the light falling on it. When a particular LED / LDR pair is above  the white surface  the reflected light falls on the LDR and its resistance drops, conversely when the LED / LDR pair is above  the black  line, its resistance rises.  This variation in resistance of the LDRs are used to asses the orientation of the line follower robot in the X-Y plane. The figure shown below depicts the sensor circuit.</div>
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<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEhitut8nOstuMAi4zxtg-6-JgNQ61ouoC0WThnS1htnfDtuXH6FUiZ_aceSzx6aALkoPJrtG67ttqgdaqP2qjF-mUmpgqRfEDkOwwNdh2q1FJfJMgU0rQWLWgfahwLwpUnj6dgiXn1ZiMdH/s1600/LINE+FOLLOWER+ROBOT+USING+8051.png" /></div>
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In the circuit, resistors R1 and R2 limits the current through the illuminating LEDs D1 and D2. Resistors R3, R5 and R6, R8 forms a voltage divider network together with the corresponding LDRs. The output of the sensor circuit is taken from the points labelled A and B in the circuit diagram.The table below shows the voltage at nodes A and B for the possible orientations of the sensor module.</div>
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<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg-n0xl5fM1q2SFFnEQ45pP3LsJMEPshJPRXHvzrmqNtz10L9aEI1M7CY8GyteSpAZf-RvfG-5ikAh5dl9mSCfT5jXVM0kPTnuqmwfoIIJzyiR8C-g8WWjjPc7ZPukPd16mwKJwKx-ie6PN/s1600/LINE+FOLLOWER+ROBOT+USING+8051.png" /></div>
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<b>Comparator Circuit</b></div>
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The job of the comparator circuit is to convert analog voltage output of the sensor into a digital format for the microcontroller to read. The comparator circuit is built around opamp IC  LM324 (IC1). LM324 is a general purpose quad opamp which can be operated from a single supply. Out of the four comparators inside LM324, only two are used here. One for the left side and the other for the right side. Circuit diagram of the comparator section is shown in the figure below.</div>
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<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEig_DlWmNKs-IxJnMYHitv3TRUegT5tqkgcyPd0Pn6LUaosYMO4mq4Qw6x6b7sH4L9xvjweaFy7IThIv9VK0_oQ0IUj17ASL7XyIYd6juD-q_jgZ_NdP3cxkQZ-BkjkswCyxPtmKZqyI7pr/s1600/LINE+FOLLOWER+ROBOT+USING+8051.png" /></div>
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Preset resistor R10 and R11 are used to set the 1V reference  for the left and right comparators respectively. Output from the left and right sensors (node A and B) are connected to the non inverting input on the left and right comparators. Output of the left comparator is connected to P1.o of the microcontroller and output of the right comparator is connected to P1.1 of the microcontroller. Both comparators are wired in non inverting mode and the table given below shows their output  voltage with respect to the possible input voltage combinations.</div>
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<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiEcWXTSTH14N3JcyveBP6y3n_3kfKdbM0aHoA1oO-Wv-z2N51So9_nHC2iMGLQVCca6I6EjhZdsxePdgcCgqaUaAGFOhromSTQQdBlMZDmb8CFdTeJlJXP6yhg6ZFGTIdiu5S3kZfffFHI/s1600/LINE+FOLLOWER+ROBOT+USING+8051.png" /></div>
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<b>Microcontroller (AT89S52)</b></div>
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The task of the microcontroller here is to control the left and right motors according to the feedback signals from the left and right comparators so that the robot remains on the correct path (the black line). The logic executed by the microcontroller for keeping the robot in track is illustrated in the table below.</div>
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<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjR1hei8l7L4xllHBFpmxay7zwm1AND6B_RkzLQUlKFVklfuUSnihKdQ265puCoAufdFabZn9MPOnxeKK08mD3pHFUq6dhQH1ima3xFIg4AZC9kCUzj0yQ34A44NFXmavLZ1P8t75WK7Z7N/s1600/LINE+FOLLOWER+ROBOT+USING+8051.png" /></div>
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<b>Motor Driver Circuit</b></div>
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The job of the motor driver circuit  is to drive the motors according to the output signals from the microcontroller. The motor driver circuit is based on ULN2003A IC. ULN2003A is a high current (500mA), high voltage (50V) darlington array consisting of seven darlington pairs with common emitter and open collector. Out of the seven channels available in the IC,only two are used here. One for the left channel and one for the right channel. Schematic of the motor driver circuit is shown in the figure below. The operation of  ULN2003 is very simple to explain. When a particular input line (say pin 1) is made high the corresponding output line (pin 16 goes low) and vice versa.</div>
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<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEg2tLGpMjcW2hWPTXVRJeqKHPFQrY9Kic7DLqkZ1XwyDrx6V-ROGLeiMZZwEqosvE65kRzgY7kgXCa_I4RmNKKfUZ2lNjcmnX8259c_v_xPzpxFA1DKgSKg5XTnEr2-tPfnzTDcqUCrDyf-/s1600/LINE+FOLLOWER+ROBOT+USING+8051.png" /></div>
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Capacitors C4 and C5  isolates the remaining parts of the circuit from the electric interference produced by the motor. The back emf voltage produced when  motor is switched and the voltage spikes due to arcing of brushes mainly accounts for the above said electrical interference. These capacitors are very essential and without them you can expect sudden crashes from the microcontroller side.</div>
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<b>Complete Circuit Diagram</b></div>
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<a href="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpvhZPfNIuL2HEbME1_i96iPKsvEzRaq0uk31a1s6Kt0wMPkFXHP-vFnRKzPhQP0gutp_U2Xfmxdamhi7n2a4lgSwaD2Oao-jfaiZaTVfY03QdSy6rxyaeHXUaiDqsVDHTki9QprrzL4-Q/s1600/line+follower+robot+using+8051.png" imageanchor="1" style="margin-left: 1em; margin-right: 1em;"><img border="0" height="274" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgpvhZPfNIuL2HEbME1_i96iPKsvEzRaq0uk31a1s6Kt0wMPkFXHP-vFnRKzPhQP0gutp_U2Xfmxdamhi7n2a4lgSwaD2Oao-jfaiZaTVfY03QdSy6rxyaeHXUaiDqsVDHTki9QprrzL4-Q/s1600/line+follower+robot+using+8051.png" width="640" /></a></div>
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Switch S1, capacitor C3 and resistor R9 forms a debouncing reset circuit for the microcontroller. Capacitors C1, C2 and 12MHz crystal X1 are associated with the microcontroller’s clock circuit. R12 and R13 are pull-up resistors. Remaining sections of the circuit were explained already.</div>
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<b>Program</b></div>
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ORG 000H                 // origin</div>
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MOV P1,#00000011B        // sets port 1 as input port</div>
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MOV P0,#00000000B        // sets port 0 as output port</div>
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BACK : MOV P0,#00000011B  // starts both motors</div>
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              JB P1.0, LABEL1 // branches to LABEL1 if left sensor is ON</div>
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              CLR P0.0           // stops left motor</div>
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              SETB P0.1          // runs right motor</div>
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              ACALL WAIT1        // calls WAIT1 subroutine</div>
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              SJMP BACK          // jumps back to the BACK loop</div>
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LABEL1 : JB P1.1, LABEL2 // branches to LABEL2 if right sensor is ON</div>
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                  SETB P0.0         // runs left motor</div>
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                  CLR P0.1          // stops right motor</div>
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                  ACALL WAIT2       // calls WAIT2 subroutine</div>
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                  SJMP BACK         // jumps back to the BACK loop</div>
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LABEL2 : SJMP BACK         // jumps back to the BACK loop</div>
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WAIT1 : JNB P1.0,WAIT1 // waits until robot is back from rightward deviation</div>
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                RET              // returns from WAIT1 subroutine</div>
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WAIT2 : JNB P1.1,WAIT2 // waits until robot is back from leftward deviation</div>
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                RET                 // returns from WAIT2 subroutine</div>
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                END                       // end statement</div>
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<b>About the Program</b></div>
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The first part of the program initializes Port 1 as input port and Port 0 as output part. After this,  both motors are started so that the robot goes straight. Then the programs checks whether there is a deviation to right. If there is a deviation to right, the program stops left motor and runs right motor and waits until the robot comes back from the deviation. When the robot is back on line again, both motors are started.</div>
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If there is no deviation to right, the program checks for a deviation to left. If there is a deviation to left, left motor is stopped and right motor is activated. This condition is maintained until the robot is back on track. When the robot is back on track again, both motors are started. Lastly if there is no deviation to left or right, both motors are kept ON.</div>
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<b>Notes</b></div>
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<ol>
<li>A 6V battery can be used for powering the circuit even though  the power supply shown in the circuit diagram is 5V DC.</li>
<li>For setting up the robot, place the robot on the line so that both the sensor pairs point on white and the black line goes in between them. Then adjust preset resistors R10 and R11 so that the LEDs D3 and D4 glows.</li>
<li>Sensor LEDs D1 and D2 are  ultra-bright green LEDs.</li>
<li>OP-Amp output LEDs D3 and D4 are general purpose, miniature, yellow LEDs.</li>
<li>Sensor LDRs R4 and R7 are general purpose LDRs.</li>
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Line Follower Robot using 8051

Line follower robots were one of the earliest automatic guided robots. They are able to follow a line marked on a contrasting background, ...

Interfacing Hex Keypad to 8051

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This article is about interfacing a hex key pad to 8051 microcontroller. A clear knowledge on interfacing hex key pad to 8051 is  very essential  while designing embedded system projects which requires character or numeric input or both. For example projects like digital code lock, numeric calculator etc. Before going to the interfacing in detail, let’s have a look at the hex keypad.</div>
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<b>Hex Keypad</b></div>
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Hex key pad is essentially a collection of 16 keys arranged in the form of a 4×4 matrix. Hex key pad usually have keys representing numerics 0 to 9 and characters A to F. The simplified diagram of a typical hex key pad is shown in the figure below.<br />
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<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEj1HnQ1ZSwiur1qw2n1Rh14orAG_YWZ-C00N2WKC9TQsMkGhTxBRwWY6zae9MeYELpB2vQ4Xld4cUjC5UsAviS_BAht41VjwR3voNdOwwXxnr5OG4IYqpuql8i5Kz1BBZS6U37AA_xgjqld/s1600/INTERFACING+HEX+KEYPAD+TO+8051.png" /></div>
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The hex keypad has 8 communication lines namely R1, R2, R3, R4, C1, C2, C3 and C4.  R1 to R4 represents the four rows and C1 to C4 represents the four columns. When a particular key is pressed the corresponding row and column to which the terminals of the key are connected gets shorted. For example if key 1 is pressed row R1 and column C1 gets shorted and so on. The program identifies which key is pressed by a method known as column scanning. In this method a particular row is kept low (other rows are kept high) and the columns are checked for low. If a particular column is found low then that means that the key connected between that column and the corresponding row (the row that is kept low) is been pressed. For example if  row R1 is initially kept low and column C1 is found low during scanning, that means key 1 is pressed.</div>
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<b>Circuit Diagram</b></div>
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The circuit diagram for demonstrating interfacing hex keypad to 8051 is shown below.Like previous 8051 projects, AT89S51 is the microcontroller used here. The circuit  will display the character/numeric pressed on a seven segment LED display. The circuit is very simple and it uses only two ports of the microcontroller, one for the hex keypad and the other for the seven segment LED display.<br />
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<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEh85rG_O8nCo_FtXjadMIlBd_NL25hrcgJCK5bVlJluKedlfdLkSvvCoCRThfpB4bDp4KEBmwIGbkQVLeSW9t8xRglYP1y7HLBvgTKdW4FYmUPb_utTTfSj2t_BtYG0u-i9E20O2z76SUv9/s1600/INTERFACING+HEX+KEYPAD+TO+8051.png" /></div>
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The hex keypad is interfaced to port 1 and seven segment LED display is interfaced to port 0 of the microcontroller. Resistors R1 to R8 limits the current through the corresponding segments of the LED display. Capacitors C1, C2 and crystal X1 completes the clock circuitry for the microcontroller. Capacitor C3, resistor R9 and push button switch S1 forms a debouncing reset mechanism.</div>
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<b>Program</b></div>
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ORG 00H</div>
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MOV DPTR,#LUT  // moves starting address of LUT to DPTR</div>
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MOV A,#11111111B  // loads A with all 1's</div>
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MOV P0,#00000000B  // initializes P0 as output port</div>
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BACK : MOV P1,#11111111B  // loads P1 with all 1's</div>
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              CLR P1.0  // makes row 1 low</div>
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              JB P1.4,NEXT1  // checks whether column 1 is low and jumps to NEXT1 if not low</div>
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              MOV A,#0D  // loads a with 0D if column is low (that means key 1 is pressed)</div>
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              ACALL DISPLAY  // calls DISPLAY subroutine</div>
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              NEXT1 : JB P1.5,NEXT2  // checks whether column 2 is low and so on...</div>
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              MOV A,#1D</div>
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              ACALL DISPLAY</div>
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NEXT2 : JB P1.6,NEXT3</div>
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                MOV A,#2D</div>
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                ACALL DISPLAY</div>
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NEXT3 : JB P1.7,NEXT4</div>
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                MOV A,#3D</div>
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                ACALL DISPLAY</div>
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NEXT4 : SETB P1.0</div>
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                CLR P1.1</div>
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                JB P1.4,NEXT5</div>
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                MOV A,#4D</div>
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                ACALL DISPLAY</div>
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NEXT5 : JB P1.5,NEXT6</div>
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                MOV A,#5D</div>
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                ACALL DISPLAY</div>
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NEXT6 : JB P1.6,NEXT7</div>
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                MOV A,#6D</div>
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                ACALL DISPLAY</div>
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NEXT7 : JB P1.7,NEXT8</div>
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                MOV A,#7D</div>
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                ACALL DISPLAY</div>
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NEXT8 : SETB P1.1</div>
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                CLR P1.2</div>
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                JB P1.4,NEXT9</div>
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                MOV A,#8D</div>
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                ACALL DISPLAY</div>
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NEXT9 : JB P1.5,NEXT10</div>
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                MOV A,#9D</div>
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                ACALL DISPLAY</div>
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NEXT10 : JB P1.6,NEXT11</div>
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                  MOV A,#10D</div>
<div style="text-align: justify;">
                  ACALL DISPLAY</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
NEXT11 : JB P1.7,NEXT12</div>
<div style="text-align: justify;">
                  MOV A,#11D</div>
<div style="text-align: justify;">
                  ACALL DISPLAY</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
NEXT12 : SETB P1.2</div>
<div style="text-align: justify;">
                  CLR P1.3</div>
<div style="text-align: justify;">
                  JB P1.4,NEXT13</div>
<div style="text-align: justify;">
                  MOV A,#12D</div>
<div style="text-align: justify;">
                  ACALL DISPLAY</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
NEXT13 : JB P1.5,NEXT14</div>
<div style="text-align: justify;">
                  MOV A,#13D</div>
<div style="text-align: justify;">
                  ACALL DISPLAY</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
NEXT14 : JB P1.6,NEXT15</div>
<div style="text-align: justify;">
                  MOV A,#14D</div>
<div style="text-align: justify;">
                  ACALL DISPLAY</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
NEXT15 : JB P1.7,BACK</div>
<div style="text-align: justify;">
                  MOV A,#15D</div>
<div style="text-align: justify;">
                  ACALL DISPLAY</div>
<div style="text-align: justify;">
                  LJMP BACK</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
DISPLAY : MOVC A,@A+DPTR  // gets digit drive pattern for the current key from LUT</div>
<div style="text-align: justify;">
                    MOV P0,A  // puts corresponding digit drive pattern into P0</div>
<div style="text-align: justify;">
                    RET</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
LUT : DB 01100000B // Look up table starts here</div>
<div style="text-align: justify;">
           DB 11011010B</div>
<div style="text-align: justify;">
           DB 11110010B</div>
<div style="text-align: justify;">
           DB 11101110B</div>
<div style="text-align: justify;">
           DB 01100110B</div>
<div style="text-align: justify;">
           DB 10110110B</div>
<div style="text-align: justify;">
           DB 10111110B</div>
<div style="text-align: justify;">
           DB 00111110B</div>
<div style="text-align: justify;">
           DB 11100000B</div>
<div style="text-align: justify;">
           DB 11111110B</div>
<div style="text-align: justify;">
           DB 11110110B</div>
<div style="text-align: justify;">
           DB 10011100B</div>
<div style="text-align: justify;">
           DB 10011110B</div>
<div style="text-align: justify;">
           DB 11111100B</div>
<div style="text-align: justify;">
           DB 10001110B</div>
<div style="text-align: justify;">
           DB 01111010B</div>
<div style="text-align: justify;">
END</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<b>About the Program</b></div>
<div style="text-align: justify;">
Firstly the program initializes port 0 as an output port by writing all 0′s to it and port 1 as an input port by writing all 1′s to it. Then the program makes row 1 low by clearing P1.0 and scans the columns one by one for low using JB instruction.If column C1 is found low, that means 1 is pressed and accumulator is loaded by zero and DISPLAY subroutine is called. The display subroutine adds the content in A with the starting address of LUT stored in DPTR and loads A with the data to which the resultant address points (using instruction MOVC A,@A+DPTR). The present data in A will be the digit drive pattern for the current key press and this pattern is put to Port 0 for display. This way the program scans for each key one by one and puts it on the display if it is found to be pressed.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<b>Important Points</b></div>
<div style="text-align: justify;">
<ol>
<li>The 5V DC power supply must be well regulated and filtered.</li>
<li>Column scanning is not the only method to identify the key press. You can use row scanning also. In row scanning a particular column is kept low (other columns are kept high) and the rows are tested for low using a suitable branching instruction. If a particular row is observed low then that means that the key connected between that row and the corresponding column (the column that is  kept low) is been pressed. For example if  column C1 is initially kept low and row R1  is observed low during scanning, that means key 1 is pressed.</li>
<li>A membrane type hex keypad was used during the testing. Push button switch type and dome switch type will also work. I haven’t checked other types.</li>
<li>The display used was a common cathode seven segment LED display with type number ELK5613A. This is just for information and any general purpose common cathode 7 segment LED display will work here.</li>
</ol>
</div>
</div>

Interfacing Hex Keypad to 8051

This article is about interfacing a hex key pad to 8051 microcontroller. A clear knowledge on interfacing hex key pad to 8051 is very ess...

Interfacing Dot Matrix LED Display to 8051

<div dir="ltr" style="text-align: left;" trbidi="on">
<div style="text-align: justify;">
An LED dot matrix display consists of a matrix of  LED’s arranged in a rectangular configuration. The desired character or graphics can be displayed by switching ON /OFF  a desired configuration of LED’s. Common display configurations available are 7×5, 8×8, 7×15, etc. LED dot matrix can be used in simple display applications where the resolution is not a big concern.  The figure below shows the arrangement of LEDs in a typical 7×5 dot matrix display.</div>
<div style="text-align: center;">
<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEgcHAhBeeghdcgKLbaXuo6ruDwrxUHmNErT4BXsmpcUYOabcezgu1hI-ASU-1I8uj4qS4EdK9PJTeSEKIApkJ5i0okO2_TXafeGBR4ycacs4WpUioFc6jcuKRrWmrgsY1bEvoWU17jmqsUW/s1600/interfacing+dot+matrix+led+display+to+8051.png" /></div>
<div style="text-align: justify;">
Any individual LED or a group of LEDs in the matrix can be activated by switching the required number of rows and columns. For example, in the above figure if  Row1 is made high and Column1 is made low, the top left LED (address R1C1) will glow. As a demonstration, lets see how we can display letter “A” using the display. The tables given below shows the logic levels at each pin  for displaying A.</div>
<div style="text-align: justify;">
<div style="text-align: center;">
<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEiIvTKgpTLvPEd6Y062Lc0DWXzbL6E24056hzrdN-W5bQjaF-a5u0m9GVPdggQ3SkZ5o21EBSAx4h2Kj8LAI3BcQli2z_xYjWULvNlMRqa2LEeMnw2gtOudd7FzngLNYK_jwoW-KuEmYVht/s1600/interfacing+dot+matrix+led+display+to+8051.png" /></div>
</div>
<div style="text-align: justify;">
<div style="text-align: center;">
<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEizpAu8rY9_AwD3Ac5B9A7K-INXNXTidZiYaFY5F1qMFaPa8eLnOxuWtUOpH77Wz9_iYTWmS1O07hs1FQLT0MtIDstYeWWBzdU1tBVt_BIVMobD3nO0S4QW1Og3F12dIRwwrWsScvMCbyDO/s1600/interfacing+dot+matrix+led+display+to+8051.png" /></div>
</div>
<div style="text-align: justify;">
In the above diagram you can see that only one LED in a row will be ON at a time but any number of  LEDs in a column can be ON at a time.  That means the microcontroller’s port pin can directly drive a row but it requires  additional circuit for driving the column lines.  The circuit diagram for interfacing dot matrix display and 8051 microcontroller is shown below.</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<b>Circuit Diagram</b><br />
<b><br /></b></div>
<div style="text-align: justify;">
<div style="text-align: center;">
<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjgQlUfpXlOjDhNizSD6JyfcRpjRlGvMiguYtBeaK2XPVl2P1ei24Nnkbf462QukLAadxFEX-miAr0Q5BODqmNYqH9ehXZr48H6QPmtm9uGszxEXbfhh3BxN2K62jd28nJH3XKmXYEGNPQJ/s1600/interfacing+dot+matrix+led+display+to+8051.png" /></div>
</div>
<div style="text-align: justify;">
<br /></div>
<div style="text-align: justify;">
<b>ULN2003A Driver IC</b></div>
<div style="text-align: justify;">
The purpose of ULN2003A here is to drive the column lines of the display. ULN2003A is a high voltage (50V), high current (500mA per channel) darlington transistor array. Each IC has 7 channels with individual output clamp diodes. ULN2003A  an active high device, which means a logic high must be applied to the input  to make the corresponding output high. The input pins are designated as 1B, 2B, 3B, 4B, 5B, 6B, 7B while corresponding output pins are designated as 1C, 2C, 3C, 4C, 5C, 6C, 7C.  The pin configuration and simplified internal logic of ULN2003A is shown in the figure below.</div>
<div style="text-align: justify;">
<div style="text-align: center;">
<img src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEjaAeuNh4blGx8qsLoTXKBd5TzgarBj08rTWyA1itJqiWNMObvdyIxoLM2UgSwZKIW7k1yk8Kx5eKLJF9JlThl-CpAAa-2iTX1J9yv6MiIYiKMRVsNBF2ci7deD9AwERMo5j6FV4TNbv3SZ/s1600/interfacing+dot+matrix+led+display+to+8051.png" /></div>
</div>
<div style="text-align: justify;">
<br />
<b>Program</b><br />
<b><br /></b></div>
<div style="text-align: justify;">
<table border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: none; mso-border-alt: solid windowtext .5pt; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext; mso-padding-alt: 0in 5.4pt 0in 5.4pt;">
 <tbody>
<tr style="height: 22.0pt; mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="border: solid windowtext 1.0pt; height: 22.0pt; mso-border-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-left: none; border: solid windowtext 1.0pt; height: 22.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">ORG 00H</td>
  <td style="border-left: none; border: solid windowtext 1.0pt; height: 22.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 13.9pt; mso-yfti-irow: 1;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 13.9pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 13.9pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P3 , #00000000B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 13.9pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258">// initializes port 3 as output port</td>
 </tr>
<tr style="height: 10.75pt; mso-yfti-irow: 2;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 10.75pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 10.75pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P1 , #00000000B </td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 10.75pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258">// initializes port 1 as output port</td>
 </tr>
<tr style="height: 3.5pt; mso-yfti-irow: 3;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73">MAIN:</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P3 , #01111110B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 17.5pt; mso-yfti-irow: 4;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P1 , #11111110B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 18.4pt; mso-yfti-irow: 5;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 18.4pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 18.4pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">ACALL DELAY</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 18.4pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 16.6pt; mso-yfti-irow: 6;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 16.6pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 16.6pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P3 , #00010001B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 16.6pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 17.5pt; mso-yfti-irow: 7;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P1 , #11111101B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 17.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 3.5pt; mso-yfti-irow: 8;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">ACALL DELAY</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 3.5pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 9;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P3 , #00010001B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 10;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P1 , #11111011B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 11;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">ACALL DELAY</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 12;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P3 , #00010001B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 13;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P1 , #11110111B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 14;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">ACALL DELAY</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 15;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P3 , #01111110B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 16;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV P1 , #11101111B</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 17;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">ACALL DELAY</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 18;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">SJMP MAIN</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258">// jumps back to the main loop</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 19;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73">DELAY:</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">MOV R6 , #255D</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258">// 1ms delay subroutine</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 20;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73">HERE:</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">DJNZ R6 , HERE</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 21;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">RET</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
<tr style="height: 14.35pt; mso-yfti-irow: 22; mso-yfti-lastrow: yes;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 54.8pt;" valign="top" width="73"><div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 153.0pt;" valign="top" width="204">END</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 14.35pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 193.5pt;" valign="top" width="258"><div class="MsoNormal">
<br /></div>
</td>
 </tr>
</tbody></table>
</div>
</div>

Interfacing Dot Matrix LED Display to 8051

An LED dot matrix display consists of a matrix of LED’s arranged in a rectangular configuration. The desired character or graphics can be...

Delay Using 8051 Timer

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<div style="text-align: justify;">
<span style="font-family: inherit;">The 8051 microcontroller has two independent 16 bit up counting timers named Timer 0 and Timer 1 and this article is about generating time delays using the 8051 timers. Generating delay using pure software loops have been already discussed here but such delays are poor in accuracy and cannot be used in sensitive applications. Delay using timer is the most accurate and surely the best method.</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">A timer can be generalized as a multi-bit counter which increments/decrements itself on receiving a clock signal and produces an interrupt signal up on roll over. When the counter is running on the processor’s clock , it is called a “Timer”, which counts a predefined number of processor clock pulses and  generates a programmable delay. When the counter is running on an external clock source (may be a periodic or aperiodic external signal) it is called a “Counter” itself and it can be used for counting external events.</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">In  8051, the oscillator output is divided by 12 using a divide by 12 network and then fed to the Timer as the clock signal. That means for an 8051 running at 12MHz, the timer clock input will be  1MHz. That means the the timer advances once in every 1uS and the maximum time delay possible using a single 8051 timer is ( 2^16) x (1µS) = 65536µS. Delays longer than this can be implemented by writing up a basic delay program using timer and then looping it for a required number of time. We will see all these in detail in next sections of this article.</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><b>Designing a delay program using 8051 timers</b></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">While designing delay programs in 8051, calculating the initial value that has to be loaded inot TH and TL registers forms a very important thing. Let us see how it is done.</span></div>
<div style="text-align: justify;">
</div>
<ol>
<li><span style="font-family: inherit;">Assume the processor is clocked by a 12MHz crystal.</span></li>
<li><span style="font-family: inherit;">That means, the timer clock input will be 12MHz/12 = 1MHz</span></li>
<li><span style="font-family: inherit;">That means, the time taken for the timer to make one increment = 1/1MHz = 1uS</span></li>
<li><span style="font-family: inherit;">For a time delay of “X” uS the timer has to make “X” increments.</span></li>
<li><span style="font-family: inherit;">2^16 = 65536 is the maximim number of counts possible for a 16 bit timer.</span></li>
<li><span style="font-family: inherit;">Let TH be the value value that has to be loaded to TH registed and TL be the value that has to be loaded to TL register.</span></li>
<li><span style="font-family: inherit;">Then, THTL =  Hexadecimal equivalent of (65536-X) where (65536-X) is considered in decimal.</span></li>
</ol>
<br />
<div style="text-align: justify;">
<span style="font-family: inherit;"><b>Example</b></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">Let the required delay be 1000uS (ie; 1mS).</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">That means X = 1000</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">65536 – X =  65536 – 1000 = 64536.</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">64536 is considered in decimal and converting it t0 hexadecimal gives FC18</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">That means THTL = FC18</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">Therefore TH=FC and TL=18</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><b>Program for generating 1ms delay using 8051 timer</b></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">The program shown below can be used for generating 1mS delay and it is written as a subroutine so that you can call it anywhere in the program. Also you can put this in a loop for creating longer time delays (multiples of 1mS). Here Timer0 of 8051 is used and it is operating in MODE1 (16 bit timer).</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<table align="left" border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: none; margin-left: 6.75pt; margin-right: 6.75pt; mso-border-alt: solid windowtext .5pt; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext; mso-padding-alt: 0in 5.4pt 0in 5.4pt; mso-table-anchor-horizontal: column; mso-table-anchor-vertical: paragraph; mso-table-left: -10.2pt; mso-table-lspace: 9.0pt; mso-table-rspace: 9.0pt; mso-table-top: 48.05pt;">
 <tbody>
<tr style="height: 21.0pt; mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<span style="font-family: inherit;">DELAY<o:p></o:p></span></div>
</td>
  <td style="border-left: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
<span style="font-family: inherit;">MOV TMOD,#00000001B<o:p></o:p></span></div>
</td>
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  <div class="MsoNormal">
<span style="font-family: inherit;">// Set Timer0 to MODE1 (16-bit timer). Timer1 is not used<o:p></o:p></span></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 1;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
<span style="font-family: inherit;">MOV TH0,#0FCH<o:p></o:p></span></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 3.8in;" valign="top" width="365">
  <div class="MsoNormal">
<span style="font-family: inherit;">//Loads TH0 register with FCH<o:p></o:p></span></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 2;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
<span style="font-family: inherit;">MOV TL0,#018H<o:p></o:p></span></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 3.8in;" valign="top" width="365">
  <div class="MsoNormal">
<span style="font-family: inherit;">// Loads TL0 register with 18H<o:p></o:p></span></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 3;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
<span style="font-family: inherit;">SETB TR0<o:p></o:p></span></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 3.8in;" valign="top" width="365">
  <div class="MsoNormal">
<span style="font-family: inherit;">// Starts the Timer0<o:p></o:p></span></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 4;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<span style="font-family: inherit;">HERE<o:p></o:p></span></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
<span style="font-family: inherit;">JNB TF0,HERE<o:p></o:p></span></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 3.8in;" valign="top" width="365">
  <div class="MsoNormal">
<span style="font-family: inherit;">// Loops here until TF0 is set (i.e. until roll over)<o:p></o:p></span></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 5;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
<span style="font-family: inherit;">CLR TR0<o:p></o:p></span></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 3.8in;" valign="top" width="365">
  <div class="MsoNormal">
<span style="font-family: inherit;">// Stop Timer0<o:p></o:p></span></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 6;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
<span style="font-family: inherit;">CLR TF0<o:p></o:p></span></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 3.8in;" valign="top" width="365">
  <div class="MsoNormal">
<span style="font-family: inherit;">// Clears TF0 flag<o:p></o:p></span></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 7; mso-yfti-lastrow: yes;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
<span style="font-family: inherit;">RET<o:p></o:p></span></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 3.8in;" valign="top" width="365">
  <div class="MsoNormal">
<br /></div>
</td>
 </tr>
</tbody></table>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">The above delay routine can be looped twice in order to get a 2ms delay and it is shown in the program below.</span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<table align="left" border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: none; margin-left: 6.75pt; margin-right: 6.75pt; mso-border-alt: solid windowtext .5pt; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext; mso-padding-alt: 0in 5.4pt 0in 5.4pt; mso-table-anchor-horizontal: column; mso-table-anchor-vertical: paragraph; mso-table-left: -10.2pt; mso-table-lspace: 9.0pt; mso-table-rspace: 9.0pt; mso-table-top: 48.05pt;">
 <tbody>
<tr style="height: 21.0pt; mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
MAIN<o:p></o:p></div>
</td>
  <td style="border-left: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV R6,#2D<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 1;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
LOOP<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
ACALL DELAY<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 2;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
DJNZ R6,LOOP<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 3;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SJMP MAIN<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 4;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
DELAY<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TMOD,#00000001B<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 5;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TH0,#0FCH<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 6;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TL0,#018H<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 7;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SETB TR0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 8;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
HERE<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
JNB TF0,HERE<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 9;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR TR0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 10;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR TF0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 11; mso-yfti-lastrow: yes;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
RET<o:p></o:p></div>
</td>
 </tr>
</tbody></table>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;"><b>Important points to remember while using timers</b></span></div>
<div style="text-align: justify;">
</div>
<ul>
<li><span style="font-family: inherit;">Once timer flag (TF) is set, the programmer must clear it before it can be set again.</span></li>
<li><span style="font-family: inherit;">The timer does not stop after the timer flag is set. The programmer must clear the TR bit in order to stop the timer.</span></li>
<li><span style="font-family: inherit;">Once the timer overflows, the programmer must reload the initial start values to the TH and TL registers to begin counting up from.</span></li>
<li><span style="font-family: inherit;">We can configure the desired timer to create an interrupt when the TF flag is set.</span></li>
<li><span style="font-family: inherit;">If  interrupt is not used, then we have to check the timer flag (TF) is set using some conditional branching instruction. </span></li>
<li><span style="font-family: inherit;">Maximum delay possible using a single 8051 timer is 65536µS and minimum is 1µS provided that you are using a 12MHz crystal for clocking the microcontroller.</span></li>
</ul>
<br />
<div style="text-align: justify;">
<span style="font-family: inherit;"><b>Square wave generation using 8051 timer</b></span></div>
<div style="text-align: justify;">
<span style="font-family: inherit;">Square waves of any frequency (limited by the controller specifications) can be generated using the 8051 timer. The technique is very simple. Write up a delay subroutine with delay equal to half the time period of the square wave. Make any port pin high and call the delay subroutine. After the delay subroutine is finished, make the corresponding port pin low and call the delay subroutine gain. After the subroutine  is finished , repeat the cycle again. The result will be a square wave of the desired frequency at the selected port pin. The circuit diagram is shown below and it can be used for any square wave, but the program has to be accordingly. Programs for different square waves are shown below the <b>circuit diagram</b>.</span></div>
<table align="center" cellpadding="0" cellspacing="0" class="tr-caption-container" style="margin-left: auto; margin-right: auto; text-align: center;"><tbody>
<tr><td style="text-align: center;"><img border="0" height="640" src="https://blogger.googleusercontent.com/img/b/R29vZ2xl/AVvXsEi5CuYSC3RfzJVdd9EXcadz6f93v8EBdEcRPbs9zmGGj3x5WfcZ9BO1vl2Afhfkh65dubJji79ADzv_S9-bwFn-1GvCHqGQURgtBY_le74TUDJjQdG4A5ea-X-kmKVKQ6uo-b_GiC0pKSsP/s1600/delay+using+timer.jpg" width="640" /></td></tr>
<tr><td class="tr-caption" style="text-align: center;"><b><i>Fig.  Delay Using 8051 Timer Circuit</i></b></td></tr>
</tbody></table>
<div style="text-align: justify;">
<span style="font-family: inherit;"><b>1KHz Square wave using 8051 Timer</b></span></div>
<table align="left" border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: none; margin-left: 6.75pt; margin-right: 6.75pt; mso-border-alt: solid windowtext .5pt; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext; mso-padding-alt: 0in 5.4pt 0in 5.4pt; mso-table-anchor-horizontal: column; mso-table-anchor-vertical: paragraph; mso-table-left: -10.2pt; mso-table-lspace: 9.0pt; mso-table-rspace: 9.0pt; mso-table-top: 48.05pt;">
 <tbody>
<tr style="height: 21.0pt; mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-left: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV P1,#00000000B<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 1;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TMOD,#00000001B<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 2;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
MAIN<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SETB P1.0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 3;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
ACALL DELAY<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 4;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR P1.0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 5;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
ACALL DELAY<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 6;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SJMP MAIN<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 7;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
DELAY<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TH0,#0FEH<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 8;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TL0,#00CH<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 9;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SETB TR0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 10;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
HERE<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
JNB TF0,HERE<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 11;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR TR0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 12;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR TF0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 13;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SETB P1.0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 14;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
RET<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 15; mso-yfti-lastrow: yes;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
END</div>
</td></tr>
</tbody></table>
<br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><br /><div style="text-align: justify;">
<b style="font-family: inherit;">2 KHz Square wave using 8051 Timer</b></div>
<table align="left" border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: none; margin-left: 6.75pt; margin-right: 6.75pt; mso-border-alt: solid windowtext .5pt; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext; mso-padding-alt: 0in 5.4pt 0in 5.4pt; mso-table-anchor-horizontal: column; mso-table-anchor-vertical: paragraph; mso-table-left: -10.2pt; mso-table-lspace: 9.0pt; mso-table-rspace: 9.0pt; mso-table-top: 48.05pt;">
 <tbody>
<tr style="height: 21.0pt; mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-left: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV P1,#00000000B<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 1;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TMOD,#00000001B<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 2;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
MAIN<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SETB P1.0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 3;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
ACALL DELAY<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 4;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR P1.0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 5;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
ACALL DELAY<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 6;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SJMP MAIN<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 7;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
DELAY<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TH0,#0FCH<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 8;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TL0,#018H<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 9;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SETB TR0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 10;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
HERE<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
JNB TF0,HERE<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 11;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR TR0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 12;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR TF0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 13;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SETB P1.0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 14;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
RET<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 15; mso-yfti-lastrow: yes;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
END<o:p></o:p></div>
</td>
 </tr>
</tbody></table>
<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
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<div style="text-align: justify;">
<span style="font-family: inherit;"><br /></span></div>
<div style="text-align: justify;">
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<div style="text-align: justify;">
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<div style="text-align: justify;">
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<div style="text-align: justify;">
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<div style="text-align: justify;">
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<div style="text-align: justify;">
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<div style="text-align: justify;">
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<div style="text-align: justify;">
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<div style="text-align: justify;">
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<span style="font-family: inherit;"><b>10 KHz Square wave using 8051 Timer</b></span></div>
<table align="left" border="1" cellpadding="0" cellspacing="0" class="MsoNormalTable" style="border-collapse: collapse; border: none; margin-left: 6.75pt; margin-right: 6.75pt; mso-border-alt: solid windowtext .5pt; mso-border-insideh: .5pt solid windowtext; mso-border-insidev: .5pt solid windowtext; mso-padding-alt: 0in 5.4pt 0in 5.4pt; mso-table-anchor-horizontal: column; mso-table-anchor-vertical: paragraph; mso-table-left: -10.2pt; mso-table-lspace: 9.0pt; mso-table-rspace: 9.0pt; mso-table-top: 48.05pt;">
 <tbody>
<tr style="height: 21.0pt; mso-yfti-firstrow: yes; mso-yfti-irow: 0;">
  <td style="border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-left: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV P1,#00000000B<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 1;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TMOD,#00000001B<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 2;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
MAIN<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SETB P1.0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 3;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
ACALL DELAY<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 4;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR P1.0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 5;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
ACALL DELAY<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 6;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SJMP MAIN<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 7;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
DELAY<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TH0,#0FFH<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 8;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
MOV TL0,#0CEH<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 9;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SETB TR0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 10;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
HERE<o:p></o:p></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
JNB TF0,HERE<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 11;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR TR0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 12;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
CLR TF0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 13;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
SETB P1.0<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 14;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
RET<o:p></o:p></div>
</td>
 </tr>
<tr style="height: 21.0pt; mso-yfti-irow: 15; mso-yfti-lastrow: yes;">
  <td style="border-top: none; border: solid windowtext 1.0pt; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 41.4pt;" valign="top" width="55">
  <div class="MsoNormal">
<br /></div>
</td>
  <td style="border-bottom: solid windowtext 1.0pt; border-left: none; border-right: solid windowtext 1.0pt; border-top: none; height: 21.0pt; mso-border-alt: solid windowtext .5pt; mso-border-left-alt: solid windowtext .5pt; mso-border-top-alt: solid windowtext .5pt; padding: 0in 5.4pt 0in 5.4pt; width: 1.75in;" valign="top" width="168">
  <div class="MsoNormal">
END<o:p></o:p></div>
</td>
 </tr>
</tbody></table>
</div>

Delay Using 8051 Timer

The 8051 microcontroller has two independent 16 bit up counting timers named Timer 0 and Timer 1 and this article is about generating time...

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