On Fri, 22 Feb 2002, Mohit Mahajan wrote:

> I'm new to PIC. I am planning to implement a control system using PIC16F877.
...
> Can we interface an EEPROM [specifically: 24LC256, 32Kbyte Flash EEPROM
> (I2C)] to the PIC in such a way that the firmware code can be written in the
> EEPROM, from where the PIC can fetch it in packets and run it?

What you propose is *more or less* what is done in a Basic Stamp, a
circuit where you have a pic, an EEPROM, a max232 (iirc) and something
more to let it work.
You download your BASIC source into the EEPROM, then the BASIC interpreter
living in the pic firmware retrieves the source and interpretes it.
It works, quite slowly of course, but it works. I don't remember what is
the eeprom size for your source code. It is quite costly, too (say 50 USD
for a Basic Stamp II, in a rough estimate considering the approximate
price in Italy - used one, but never bought one...).

I had the same idea as yours some months ago, but I have never had the
time to try and develop something like that: the eeprom would become a
sort of hard disk for the pic, with all the difficulties involved in
building up a firmware that has to retrieve the executable (not a
BASIC source code) in blocks when needed. You need of course a kind of
operating system acting as a supervisor.

Never found (nor searched...) something like that on the Net, but as I
have sometimes seen a pic talking to an ide disk interface (similar
problem) that could be a
start point to develop a system like that.

Not a easy task for a beginner, I think.
Anybody has ever found a system like that?

Ciao
Giorgio

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