Suggestion!, Flash or external eeprom? Options

[sdujolo]

Hello,

I have a project that needs to save alot of config data ect. The eeprom in the pic is not big enough to store all data: I have alot of free flash in the PIC can I use that to store data whit read and write to flash funtions? It will not be alot of writeing and read. Or should I use a external eeprom?

[DavidT]

1. The easiest is to store data in normal RAM using variables or an array.
2. However, I suspect you are referring to program memory (ROM) which can be written to when programming with the BoostC 'rom' command and read at any time.
3. If you want your PIC program to update this data on the fly you need to have a device which supports 'self-write' ('Enhanced Flash' versions in the 16F series or available in most or all? 18F's). Harder than 1 or 2.
4. External memory will be more work than 3.
David.

[zzjoki]

1. The easiest is to store data in normal RAM using variables or an array.
2. However, I suspect you are referring to program memory (ROM) which can be written to when programming with the BoostC 'rom' command and read at any time.
3. If you want your PIC program to update this data on the fly you need to have a device which supports 'self-write' ('Enhanced Flash' versions in the 16F series or available in most or all? 18F's). Harder than 1 or 2.
4. External memory will be more work than 3.
David.

(inexperienced - my opinions)
I've been wondering the same question. Choosing serial EEPROM seems like it could lead to more choices of MCU, EEPROM size & speed, better read/write endurance (?), and maybe .... lower total cost. The 18FxxJ10 devices have no internal EEPROM but are CHEAP.

RAM is volatile and would require backup power to sustain a disruption. Writing to flash might be harder for me (newbie for ever), but once you get a few projects behind you I don't think it's going to be hard to do. Microchip documents contain examples of flash write. OTOH the 18FxxJ10 have low write cycle endurance (1000).

Anyway, it's fun to think about it all. K parts are coming out soon, too.