Tutorial: Using the C51 compiler and the PDS51 Emulation Software

I. Introduction

The goal of this tutorial is to blink an LED using the 8051. Steps are given on how to compile the program using the c51 compiler and emulate the program using the PDS51 emulation software.

II. Schematic

Wire the circuit as shown by the schematic below. It may be useful to used the 8051 pinout. Make sure the LED is connected correctly or it will not blink when you run your program. Below is another schematic which shows how the LED corresponds to it's symbol.

Schematic for Tutorial

LED schematic

III. Apparatus Required

  1. LED (1)
  2. 330k resistor (1)
  3. 5V power supply
  4. Phillips PDS51 "CE" Development System

IV. Program

   /* main.c */

   #pragma SMALL DB OE
   #include <reg51.h>
   sbit light = P2^0;
   /* Delay Function */
   void delay(void){
      int i, j;
      for(i=0; i<1000; i++){
         for(j=0; j<100; j++){
   void main(void){
         light=0;   /* turns light on */
         delay();   /* without the delay function the light
                       would blink to quickly for us to see */
         light=1;   /* turns light off */

V. Procedure

Creating The Program File

  1. Create a folder in the C directory called tutorial
  2. Type in the following program into any text editor (i.e. notepad, wordpad, ...) and save to C:\tutorial
Compiling The Program using the C51 Compiler

  1. Open a Command Prompt and go to the file location, it should be at C:\tutorial
  2. Compile the program by typing:

    • c51 tutorial.c

  3. If the compilation is sucsessful it should say:


    If there are any warnings or errors, check the code you typed against the code provided.
  4. Upon sucsessful compilation, an object file is created. Link the object file to create an executable by typing:

    • bl51 tutorial.obj to tutorial.omf

    If you have multiple object files you can link them with the following command:

    • bl51 tutorial.obj, file1.obj, file2.obj to tutorial.omf

  5. Upon sucsessful completion an execuatable, tutorial.omf, should be created. You will see the following:


    You are now ready to emulate your program.
Using The PDS51 Emulation Software

  1. Start the PDS51 software by double-clicking on the icon
  2. If the software does not recognize the emulator click on the "Setup" button
    • Under the "Communication" tag
      • Com Port->Auto
      • Baud Rate->Auto
    • Under the "Debugging" tag
      • Source Origin->Franklin C
  3. Load your executable
    • File->Load Object File
    • Select the File Type as "Franklin C"
    • Select the output file created in the previous section
  4. Begin emulation
    • Run->Run
    • There is also an icon on the tool bar which has the same functionality, it is the black arrow.
  5. If everything was done correctly, the LED should start blinking
  6. To stop the emulation
    • Run->Halt
    • There is also an icon located on the tool bar which has the same functionality, it is the red hexagon.