Set custom device serial number

[okyeron]

Earlier in the year I ported some code from Teensy to M0/M4 and for the application I need to set a custom serial number for the device (the serial number must be formatted a specific way).

setManufacturerDescriptor and setProductDescriptor are available with TinyUSB, but not serial number.

Thus I previously hacked to together changes to create a setSerialDescriptor(); function mimicking setProductDescriptor() and it worked ok in my limited testing (I believe I tested on ItsyBitsy M0 and Neotrellis M4).

I wanted to revisit this now and submit a proper PR.

However, since it's been awhile (since February), I'm a little fuzzy on my previous work. For SAMD21/SAMD51 I believe working around the defs in thegetSerialDescriptor() function in Adafruit_TinyUSB_SAMD.cpp would be required. Is that correct?

Work in progress here: https://github.com/okyeron/Adafruit_TinyUSB_ArduinoCore/tree/CustomSerialDescriptor

[hathach]

could you please submit it as PR, If it is still wip, you could make a draft one.

[okyeron]

Got my WIP working well and added comments after posting this so will PR later today.

[henrygab]

@okyeron ... this would be interesting to me also. Looking forward to seeing your work merged!