8051 and external RAM (for code) problem

hi~ everyone,

I would like to connect a external RAM (SRAM,or ...) for

code to a 8051.

Note:

The code must be placed on the external RAM

for advanced testing.


but i have no idea to load the code to the RAM.

i think it may be different from writing data to the RAM.

Can someone help me or provide the info about the issue ?

best regards

Hi.

These links might help you.

**broken link removed**
**broken link removed**

I am a newbie in this field. But i will try my best to find resonable solution for your problem.

Bye
All the best.

querybox said:

Hi.

These links might help you.

h**p://chaokhun.kmitl.ac.th/~kswichit/8051sbc/8051sbc.html
h**p://chaokhun.kmitl.ac.th/~kswichit/C52EVB/c52.htm

I am a newbie in this field. But i will try my best to find resonable solution for your problem.

Bye
All the best.

Click to expand...

but i am still unable to realize the whole development environment

,Thank you anyway !

i am a newbie ,too.

i just began this project with the ready-made devices for a few days,

and i will try my best to find the answer.

i will discuss with my instructor about the info you

provided .

another problem,

Is the monitor program

the key point to distinguish the code from the data when loading into RAM ?

Have you considered using an Eprom Emulator?

In the good old days when there were no flash based microcontrollers I used these devices a lot

You plug it into your development environment instead of the normally used Eprom and you can load your code via parallel or serial port into the Eprom Emulator and issue a reset to your MCU ...

Just search google for "eprom emulator" (without the quotes).

best regards

Hi.

These links might help you.

h**p://chaokhun.kmitl.ac.th/~kswichit/8051sbc/8051sbc.html

h**p:// 8052.com

Bye

I'm not certain that I understand your question exactly. most of the monitor programs will let you download code to ram via a serial port. so getting the code to the RAM should not be an issue.
However, if you are asking how you can then execute it. You can't if you have implemented a pure harvard architecture design. That is, you can rewd and write to data RAM but you can't execute any instructions from it. in Code memory you can read it and you can execute it, but the processor can't directly write to it.
The solution in this case is to go back to a Von Neuman architecture that is you no longer maintain separate code and data space. then you can read, write and execute from the memory.
You don't necessarily need to do this to the entire design. I designed an 8052 micro board which maintained a harvard architecture for the lower 32K of memory but used a von neuman architecture for the upper 32K of addressing. In this fashion you could now address 32K of Code only space, 32K of Data only space and 32K which could be either code or data.

I hope this helps, ------ SAKER