ProtoDAC TDA1387 X8 project

[varunach]

What do the status LEDs indicate on the Raspberry Pi? Is there normal power and SD card activity?

@hifinet yes there is. It is just unresponsive and I simply can't access 'moode.local' end point from the wifi network. If i unplug the 3.3V terminals from FifoPi Q7 and reboot it seems to work just fine. 

My full stack is as follows: PurePi >> RPi4 >> FifoPi Q7 gets its 3.3V from PurePi >> ProtoDac on top of Q7 with GPIO extender and pins 2/4 removed and gets its 5V from PurePi

For additional info, other than my previous message around troubleshooting, here are a few more things I tried.

1) I removed the Q7 altogether from this chain above and connected the ProtoDac to RPi4 (which sits on top of PurePi) directly with isolated GPIO extender, still maintaining 5V supply to ProtoDac from the PurePi. Everything works as expected and can get audio out. This tells me RPi4 and ProtoDAV is able to share the 5V PurePi supply without any issues. 
2) I also have a monitorPi which is helping a bit with troubleshooting. Connecting a MonitorPi to RPi4 GPIO (with nothing else connected) shows that it is getting audio signal via GPIO (see image with 48Khz playing). When I add the FifoPi Q7 to the GPIO stack with 3.3V still not connected, the MonitorPi doesn't show any clock or audio signal (see attached image that shows NOSIG and everything is 0). When I connect the 3.3V terminals to Q7 the clock seems to be initialized properly but still no signal via GPIO (see attached image where the 45 and 49 Khz clock signals are displayed with NOSIG). This is also when Moode becomes unresponsive and I lose access. 

Something tells me this might be related to a driver and/or clock signal related issue? Looks like @OnkelPH had the same issue so I'm curious how he got over this hurdle.