[PROBLEM] HiFiBerry Digi Pro on RPi 4 no go

[aknaggbaugh]

Thanks a lot!

After reading your feedback and a few hours of testing, I think I found an hardware issue.

The WM8804 I'm very familiar with. This chip has hw mode or sw mode. In sw mode, the chip looks at the I2C for instructions. In hw mode, the chip uses config pins for configuration. The HiFiberry driver needs the chip to be in sw mode.

During power-on reset, the WM8804 looks at the I2C lines to see if it needs to be in sw or hw mode. Now I see with the RPi 4, the WM8804 goes into hw mode which makes the driver fail. When I manually reset the WM8804 (momentarily short pin 6 to GND) and then reboot Moode, everything suddenly works until the next power cycle.

I don't know why the WM8804 goes into hw mode with the RPI 4 and works properly with RPi 3. Might be a timing issue at power up. A solution maybe is making the WM8804 reset slower on power up. Still need to try this, requires soldering.

I've heard from one person using the HiFiberry Digi Pro that had absolutely no problem on the RPi 4, I will try to figure out why mine is different.

Thanks to everyone for the help so far!

Good find! I'll try this with my Pi2Design board when I have some time and see if the same reset works for that. I'd be interested in your hardware mod solution if you get it working.