Non-volatile memory in PIC

[Nora]

pic24 non-volatile

Hi there,
I have a couple of questions about memory allocation.

I need to take in some values from a user's terminal into a separate memory chip (such as 24LC256) through a PIC processor. I have been asked to store some data in the separate memory chip, I was told this is because it is non-volatile memory.

I wonder if I could store these equations in the PIC itself. The PIC I'm using is a flash memory PIC 16F877A. Looking at the data sheet, it seems that there are a couple of different areas of memory in the PIC that can be accessed.
I do not understand the data sheet well enough to see which is RAM and which is ROM, but it seems to me that the code itself must be stored in non-volatile memory?

I would appreciate some discussion about this very much!
-NN

 

[namqn]

Flash and EEPROM are non-volatile memories in PIC16F877A. While running a program, this particular PIC can write to either its flash or its EEPROM. Normally, one would use EEPROM for a few values which are changed quite frequently, and flash for large block of constants.

Flash is erased in blocks, and written in smaller blocks (could be as small as one program word). EEPROM bytes are erased/written individually.

Hope this helps!

Cheers,

 

[Nora]

Thanks for the info, it helps a lot.

Does anyone know how to read and write to EEPROM?

Thanks!
-NN

 

[bld]

You cand find in datasheet how to write the EEPROM or FLASH memory.
If you use Hi-Tech PICC compiler there are some dedicated macros to read/write data from/to EEPROM and FLASH. You can check the manual of the compiler.