Using an EEPROM as the Program Memory ??

[johnkkk]

Hello ,

I would like to use an EEPROM 24LC256 as a program memory, for these reasons,

- Large program space 256 KBits
- Large area for a ROM
- Easily updatable firmware.

I use a programming language similar to BASIC, to make the application program. The program features are quite satisfactory( for me).

What would be life time of the EEPROM, this is important because the EEPROM is read and written continously, right from the time the hardware is switched ON.

The MCU iam using is 16F877, and PCM compiler.

bye
jj

[Mark]

No, you can not if you are trying to use it for "Program Memory". Move to a PIC18 if you need more ROM.

Now if you mean "Data Memory" then this would be possible but not if you need to write that often. You would be better off using a FRAM which looks like the eeprom but has viritually unlimited writes and is very fast for writing.

[johnkkk2]

Hello,

[Mark]

You can't run from external memory on a PIC16F877. Unless, you are actually running some sort of interpreter (scripting) language. Maybe this is what you mean by "language similar to BASIC". The actual code that is running is running from flash (inside the micro) but reads commands from the eeprom and executes them. Is this what you are doing? If so, why do you need the CCS compiler? Maybe you have the source code for an interpreter?

[PCM programmer]

Mark is talking about the Basic Stamp. If you are interested, some
of the internal workings of it are described here:
http://www.mcmanis.com/chuck/Robotics/stamp-decode.html
http://members.aol.com/stamp2book/