I am using the fork made by Hans on a Raspberry 3b+ with an Audioinjector Stereo soundcard and the hardware-paraphenalia to use Midi over UART. Add to that a 3D-printed enclosure with I2C-Display and 4 Buttons.
The hardware is alright, e.g. working under Zynthian.
When I write a fresh SD card and put it in the machine and connect a midi keyboard, it does play the generic sounds via the onboard audio/headphone plug.
As soon as I uncomment the lines for Midi over UART in the boot/config.txt file and reboot, the machine doesn't output sound anymore (samplerbox/configuration.txt is still untouched at this moment).
The problem does not go away when I reset the lines by commenting them again. I can't wrap my head around why this does happen. Does anyone have an idea?
(Inserting the dtparam... for my soundcard and setting up the confgurations.txt file for the I2C address and Buttons don't change the no sound problem. Insted I get a "I2S Sync error" and "DMA transfer could not be terminated", both connected to the sound card.
I've been through about 6 installations and the funny thing is, I think at one time I had it working and killed the whole installation by enlarging the samples partition.)