Did I fry my FV-1?

[daeg]

Playing around with a Pythagoras, I flashed it with alligator clips and a USB CH341A module that might be running at 5V.

Now I'm only getting dry signal. Tried swapping out the EEPROM. Is it possible that 5V at SCK (Pin14) and SDA (Pin15) fried it?

 

[Robert]

That's definitely a possibility. The FV-1 maximum voltage is 3.3V.

The FV-1 Dev board runs the CH341A at 3.3V to avoid overvoltage on the SCL/SDA bus lines.

 

[daeg]

That's definitely a possibility. The FV-1 maximum voltage is 3.3V.

The FV-1 Dev board runs the CH341A at 3.3V to avoid overvoltage on the SCL/SDA bus lines.

Yeah, I got impatient waiting for the CH341A IC to become available for the FV-1 dev-board so I jury-rigged one out of a Pythagoras, 3.5mm jack, headphone cable and CH341A USB module. It was a cool solution but I overlooked the 3.3V vs 5V difference. I actually flashed it that way a few times before it stopped working.

Any way to confirm that the FV-1 is dead before I cut my losses and chuck the board? I thought about grounding pin13 to try the internal programs.

 

[Robert]

Any way to confirm that the FV-1 is dead before I cut my losses and chuck the board? I thought about grounding pin13 to try the internal programs.

It'd be worth a shot at least.

 

[daeg]

Great news (for me). The problem was I was I had started flashing hex files rather than binaries.

The circuit is 100% fine. Flashing using the 5V USB CH341A module hasn't done any damage (yet).

 

[Robert]

Excellent, I was going to suggest a bad flash but since you said you swapped the EEPROM I just assumed it was with a known good one.

I'd just flash the EEPROMs out of circuit in the CH341A, no risk of damage that way.