Ok, yes I also suspect the os rather than pd…
Its unfortunately difficult to debug, since during development I did not have the problem, 
and now that the raspi and teensy are packed in a box …
The classic Heisenbug, or even Mandelbug situation:-)
I will try to come up with the “script to check if device is here, otherwise restart” idea…if someone could point me to a starting point I’d appreciate it. I’m not very steeped linux scripts….

On 03.10.2025, at 14:46, Andrew Lyons <tstexture@gmail.com> wrote:

I am going to guess that its not pd that doesn't recognize the midi device, but alsa. I have the same problem with an older pi4 I use for a pd synth. I've spent quite a bit of time trying to work out why alsa doesn't see the hifiberry card on boot without coming up with a reliable solution. It's a problem that probably needs to be elevated to those developing the operating system, and perhaps alsa specifically. In the meantime, a reboot is the only workaround I've come up with.

Best

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Andrew D Lyons | Tools Developer | https://www.sites.google.com/site/tstexture
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On Fri, Oct 3, 2025, 1:47 AM michael strohmann <itsnotfair9@gmail.com> wrote:
Hi!

A  bit off topic since probably more related to operating system:
I am running PD on a raspi5 / bookworm with a teensy as MIDI device input.
In some cases pd does not recognise the MIDI device after a restart.

Is there a way to start pd only when the system recognized the MIDI device ?

Thanks!
Michael

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