IanSB
commented
6 months ago CPLD is very sensitive to ESD! Mine got internal short after I plugged in/out cables a few times, while touching PCB leads. It just started to overheat and burn PCB. Had to replace CPLD and now it works again.
This can happen occasionally which is why I designed the various buffer boards to protect the inputs of the CPLD against that. Also plugging the CPLD board into the 40 way Pi header while powered up will almost certainly damage either the Pi or the CPLD or both as will plugging them together 'off by one' pin. (I accidentally did both of those a couple of times during development!).
Also I would replace resistor arrays with regular resistors as arrays are pretty expensive compared to resistors.
The design was optimised to make DIY assembly easy, even with just a soldering iron rather than hot air, especially for those not used to surface mount assembly so through hole parts were used where possible and larger surface mount packages were used where possible too. Hand soldering a few through hole resistor arrays is a lot easier than 15 surface mount resistors. Also for the analog board SOIC packages were chosen where possible as they can be single pin soldered with only one package being TSSOP. The pre-assembled boards available from the authorised sellers linked in the wiki have been optimised for machine assembly using much smaller components and more surface mount parts so were able to include some additional protection for the CPLD inputs when used without a buffer board.
This is not an issue but a reminder to everyone based on my experience.
CPLD is very sensitive to ESD! Mine got internal short after I plugged in/out cables a few times, while touching PCB leads. It just started to overheat and burn PCB. Had to replace CPLD and now it works again.
P.S. maybe it’s a good idea to add efuse to the schematics? Also I would replace resistor arrays with regular resistors as arrays are pretty expensive compared to resistors.
Thank you for the great product!