gnuk with GD32F103

[Karsten Müller]

Hello,

thank you very much for your response. At this weekend I had some time
to do some further trials...
So I adapted the design to FST01-SZ. But it does not work and I have no
clue what to do next. 

That is my current status:

* PCB is based on FST-01, without SPI-Chip (and other pin for USB-EN -
like nitrokey_start)
* Software compiles and works on STM32F103
* on PCB with GD32F103, programming with a simple hello world program
works and also all connections (pin toggling with test program) and
oscillator/PLL... - so chip seems OK
* Software is compiled with --target=FST01_SZ (and check, that it is
compiled with -DMHZ=96)
* with logic analyzer no USB-Packets are detected (in contrast to
STM32F103 version)
* I also test with and without USB-EN pin (once in software - comment
out define, once in hardware by desoldering resistor)
* on STM32 it only works with both enabled, on GD32 nothing works.

I wonder, because for me it seems that USB-EN is not really necessary?
(FST01_SZ version does not have this pin)

My suggestion is, that either hardware or software (maybe compile
process?) is faulty...
I know, it is against the idea/license to share binarys, but would it be
possible to get a working binary for testing ( I think, vidpid equals
zero would be OK, because there has to be any USB communication which
can be seen on logic analyzer) or a other method to test my compiled
software?

I would be happy for any hints or ideas for target-oriented debugging.

sincerely,
Karsten Müller