I wrote a usb serial program on nuvoton microcontroller, imitate uno, and use the uno's inf file.
Everything ok with the serial debugging assistant.
When arduino monitor read and write this serial, found that the host send OUT token packet is normal, and all the host sends IN packet is NAK.
I.e. monitor can send data, but can not receive data.
Descriptors have completely compatible with uno.
some suggestion?????