Introduction: 8051 SBC Small Board Computer

CPU: Any 8051 compatible with 40-pin DIP package @11.0592MHz

MEMORY: 62256, 32KB SRAM for both code and data space

Monitor Program: PAULMON2

Communication: RS232 UART

Step 1: 8051 SBC

This is a 8051 MCU based SBC with monitor program (PAULMON 2) which is used to develop 8051 based projects quicker and easier.

I have implemented the PCB according to the schematic.

In this circuit 32kB SRAM is connected to DATA and ADDRESS bus of 8051 and is available (CE chip enable) in the address range of 8000h to FFFFh. So reading and writing of DATA and COMMAND is in this range.

Step 2: Monitor Program PAULMON 2


With monitor program you can:

a) Examine and modify both the internal and expanded RAM of the microcontroller.

b) Examine the program memory of the microcontroller.

c) Examine and change any register or special function register (SFR).

d) Download a program using the Intel hex format to flash code memory.

e) Disassembly programs in flash.

f) Run step-by-step, trace, and execute downloaded programs.

g) Use software breakpoints. Hardware breakpoints are also kind of supported.

I have downloaded this file pm21_8.obj - (Ram from 8000 to FFFF, EPROM from 0000 to 1FFF,) from the above website for this Board configuration.

Now burn this object file to AT89S52 with any programer and plug that in to the board and power up.

And connect it to Computer Serial Port.

Open any serial Terminal software like Windows Hyperterminal, PuTTy etc. and connect to the board with settings like 9600 BAUD, 8 bits, 1 stop bits, no flow control.

And press ENTER key to run PAULMON2 on the serial Terminal as shown in the picture.

For list of COMMANDS refer the link

Step 3: Develop Code and Test

Now develop code using SDCC c compiler, as31 assembler and download directly to the SRAM using 'D' COMMAND in the serial terminal.

And run the downloaded program using 'J' COMMAND.

Here you can download the SDCC and as31