gnuk with GD32F103

Karsten Müller email at
Tue Mar 5 19:07:52 CET 2019


thank you very much, I am happy that it works now.

Am 04.03.19 um 06:36 schrieb NIIBE Yutaka:
> FST-01G and FST-01SZ don't use USB-EN any more.  I removed the pin
> because it is not needed.  I know a design with USB-EN, like Maple-Mini,
> and that is a reason why FST-01 has that.
> The intended use of USB-EN in FST-01 was for a device to ask host to do
> re-enumeration.  For this purpose, simply driving USB signals (D+ and
> D-) to GND is actually OK.  For strict conformance to the USB
> specification, it's better supporting high impedance state of D+.  But,
> (for me), the fixed pull-up of D+ can be acceptable, as long as it
> works.

Thanks for explanation.

> In short, I suggest removing USB-EN.  Please have a look at FST-01SZ
> schematics, it pulls-up D+ line to +3V3 directly (no USB-EN control at
> all).
While reading I realized that ESD-Protection NUF2221W1 has an integrated

When designing PCB I choose an other TVS diode and use discrete series
resistors (like in nitrokey start) but I overlooked pullup resistance in



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