Maximilian Gerhardt

Looking at the stack trace and that you get into an abort in __attachInterruptFunctionalArg, you can get into an abort call if you or a library is using attachInterrupt but...

Write ```cpp IRAM_ATTR void dmpDataReady() { mpuInterrupt = true; } ``` instead.

What do the comments in this PR have to do with the actual PR? o_o

Very interesting: the DigisparkKeyboard/Keyboard.ino demo *works* and the computer recongizes the USB device. But not with the CDC sketch..

The DigiUSB/DigiBlink.ino works as well.  But not the CDC :/

The same behavior occurrs btw with the original core (https://github.com/digistump/DigistumpArduino/). There are some forum topics about this (http://digistump.com/board/index.php/topic,2720.msg13422.html#msg13422) with some posts like >DigiCDC is an ugly hack, as CDC devices...

The general [DigisparkUSB](https://github.com/ArminJo/DigistumpArduino/tree/master/digistump-avr/libraries/DigisparkUSB) and also [DigisparkCDC](https://github.com/ArminJo/DigistumpArduino/tree/master/digistump-avr/libraries/DigisparkCDC) library use V-USB as the underlying USB library, and it also has a few words on [CDC](http://vusb.wikidot.com/usb-device-classes) >CDC requires bulk endpoints which are forbidden...

@simonovich so you have the situation that it does work in the Arduino IDE but not over PlatformIO, or have you not tested it via PlatformIO?

Just to double check, when you use the Arduino IDE and the "Pico" or "Generic" board definition, the board also does nothing? If the Arduino IDE works, it's a fault...

BTW, what is on written on the small flash chip on the top of the board? Same as in https://www.waveshare.com/media/catalog/product/cache/1/image/800x800/9df78eab33525d08d6e5fb8d27136e95/r/p/rp2040-zero-3.jpg ? The product page says it's a >W25Q16JVUXIQ >2MB NOR-Flash