Electronics and Communication Engineering Embedded System Design with 8051 and PIC Microcontroller Experiments

Implementation of Up/Down Counter

(a) To Implement an Up/Down Counter Using Two General Purpose I/O Pins as Control Inputs.

  1. Click on View Circuit Diagram to see how the 8051, 7-segment display, and control pins are connected in logic diagram and in block diagram.

  2. Click on View Assembly Code to analyse the assembly code used for this experiment.

  3. According to your analysis, write your code in the Assembly Code Editor.

  4. Click on Check Code to verify your program against the given code.
    Note:

    • If correct → a success message will appear and UP/DOWN buttons will be enabled.
    • If incorrect → you’ll be asked to review and correct your program.

  5. (Optional) You can directly copy the code into the editor by clicking on Use Code in the View Assembly Code popup.

  6. After validation, run the simulation. The 7-segment display will count in the range of 0 to 9.

  7. Click UP (P2.0) to increment the value.

  8. Click DOWN (P2.1) to decrement the value.

  9. If both UP and DOWN are clicked simultaneously, the value will not change.

  10. If you want to save your program, click Download Code. It will be stored as your_code.asm.

  11. Click on the RESET button to stop the simulation, clear the editor, and reset everything to default.

(b) To Implement an Up/Down Counter Using One Interrupt Pin as a Control Pin.


1. Click on View Circuit Diagram to see how the 8051, 7-segment display, and INT0 pin are connected in both the logic diagram and block diagram.

2. Click on View Assembly Code to analyze the assembly code used for this experiment.

3. Write your own code in the Assembly Code Editor based on your analysis.

4. Click on the Check Code button to verify your program against the given code.

Note:

  • If correct → a success message will appear and Start Count will be enabled.
  • If incorrect → you’ll be asked to review and correct your program.

5. (Optional) You can directly copy the given code into the editor by clicking Use Code in the View Assembly Code popup.

6. After validation, click on Start Count to run the simulation.

  • The 7-segment display will begin counting from 0 to 9 (UP mode by default).

7. Click on Toggle Direction (P3.2) to simulate an interrupt.

  • This will change the counting direction between UP and DOWN.

8. If you want to save your program, click on Download Code. It will be stored as your_code.asm.

9. Click on the Reset button to stop the simulation, clear the editor, and reset everything to default.