Is MIDI with GPIO serial still working as of today?

[josephernest]

See https://www.samplerbox.org/article/midiinwithrpi point 3.

Needs to be double-checked if it still works nowadays, with new kernels.

There are 3 places to check:

• https://github.com/josephernest/SamplerBox/blob/master/isoimage/root/boot/config.txt
• https://github.com/josephernest/SamplerBox/blob/master/isoimage/root/boot/cmdline.txt

• SamplerBox/samplerbox.py

  Line 387 in ea16c5f

  ser = serial.Serial('/dev/ttyAMA0', baudrate=31250)

Then we have to connect a real hardware synthesizer (e.g. Roland or Yamaha), and see if it still works.

[mojca]

I cannot check whether it works "with any hardware midi device" (I only have an Arduino), but I'm thinking of doing the reverse test first: try to open a serial connection and send some messages from RPi, while measuring the rate with oscilloscope. Once that gets confirmed, test in the other direction.

That second test sounds a bit more tricky to me because the messages might get interpreted correctly even at a slightly wrong baud rate settings.

By reading #24 it looks like one might have to verify this on:

• various Debian versions
• various RPi models (at least zero, 2B, 4)
• maybe both 32-bit and 64-bit(?)
• using both serial and USB connection
  and I'm not sure if I can cover all combinations of them, but I can try some. I won't have hardware access before the weekend (and no hardware + oscilloscope combination before next week).

When things broke for me, it might be that it was a result of some mixture of apt-get update && apt-get upgrade, switching between RPi 2B+ and RPi4, ...

What's the oldest OS that you want to target?

On https://www.raspberrypi.com/software/operating-systems/ there is a link to Debian 11 2022-04-04-raspios-bullseye-armhf-lite.img.xz, but your scripts are currently pointing to Debian 10.

[josephernest]

With oscilloscope it might work, and then finally not work on a real Roland, Yamaha synth, etc. So I'll do this test one of these days with real synthesizers, to be sure everything works without the 38400 baud hack :)

[rolfmeurer]

Python script MIDI IN via SERIAL PORT is very poor. Running status is not considered, so most keyboards produce stuck notes. The Python script then accepts neither NOTE OFF as a NOTE ON message with Velocity=0 nor NOTE OFF as a 0x8n message