I just wanted to raise an issue I had last night - FV-1 not recognising EEPROM. I think this could have been an issue at T0/pin 13 but can't be certain. I grounded the pin to confirm that the onboard fx were working and audio was passing through - all working correctly. I also checked continuity to the pin and all seemed fine. I swapped the EEPROM and tested the previous one in another build. This was the first time this issue has occurred for me in almost 100 builds (functionally the same PCB each time). Just thought I'd check to see if there's been any previous known issues that result in a similar outcome? I reflowed solder to the chip in the hope that this might resolve the issue, no dice. As a note - the custom programs would appear to run on power up for a brief moment (just a quick burst of sound that I could identify as my program) then fails. This confused me further...
It's possible there was a fault on my end at some point in the build and I was unable to locate it in my troubleshooting but as mentioned, I've built this circuit successfully many times... just a little bit nervous now cause the build takes me a while and it basically renders the board useless.
1. Post link to schematic.
2. Many times power on issues are related to the crystal. Try a larger cap on it.
3. What happens if it does the strange power on thing but you change programs? Does it read from the EEPROM or internal?
If the internal programs work correctly with T0 at 3.3v but when T0 is switched to GND and you confirm T0 pin does in fact have the correct voltage when set to GND for EXT programs. I would check the EEPROM is working, which you say it does in another pedal then the next step I would look at is the SDA /SCK connections between EEPROM and FV-1 for continuity.
EDIT.... My appologies I have T0 the wrong way around , of course 3.3v = EXTERNAL Gnd = INTERNAL
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