Using part of the EEPROM for other purposes?

[mark2]

All of my bin files are consistently 4096 bytes.
Is it safe to assume I can utilize any memory beyond that? e.g. 40 pages at the end.

And if so, does anyone know a reason why having a 2nd IC (an atmega) read from the same EEPROM might present a problem?

On my earlier pedals I had separate EEPROMs for the atmega, but I'm looking now to keep it smaller and simpler if possible.

[frank]

The biggest risk is the micro and FV-1 accessing the EEPROM at the same time, as long as that cannot happen and the EEPROM is compatible with the addressing the FV-1 uses it is possible to share the EEPROM.

[mark2]

Thanks Frank. I appreciate the reply.
Do you happen to know offhand a rough amount of time the FV-1 will take to read it after detecting a change on the patch selection pins?

My Atmega will also be reading it in response to a patch change, so I may try having it simply delay for a safe margin before reading the EEPROM.

Otherwise if this idea is too problematic I'll simply add a separate EEPROM dedicated to the atmega. (Edit: or use its internal EEPROM, though that eliminates the possibility for the player to swap out eeproms easily).

[frank]

Time depends on sample rate and switch bounce as a bouncing switch can cause it to read in one or 2 times. There is another thread here where someone was asking about why they saw different read times and addresses for programs http://www.spinsemi.com/forum/viewtopic.php?f=3&t=884

Safest thing would be to read the switch with the micro and debounce it, then have the micro read the data it needs from the eeprom, then have the micro drive the program select pins on the FV-1.

[mark2]

Of course! That's a really good idea. Thanks again! Happy holidays!