Ha Thach

```C pins::LedErr.setLevel(true); ``` it is not buildable, please also give the link to your fork that contain the exact code, it should be as minimal changes as possible.

Please attached your example folder here, that makes sure we are testing the same piece of code.

could you provide a bit more info 1. Which exact firmware you are using, if possible please check with the examples/cdc_msc, otherwise, please attached your firmware similar to how stock...

I have a second thought though, I think ZLP should only be sent when there is no data and the last packet is multiple of endpoint size) much like cdc...

@pigrew @majbthrd great analysis, I think the host expect the usbd to return ZLP packet to indicate the end of transfer. I think this is a great chance for us...

This commit https://github.com/hathach/tinyusb/commit/c8247f0907040eb86c301e8bff8bb322fc9cb566 fix ZLP issue for nrf52840. For STM32F072, it is little bit difference, the device did response with ZLP correctly, however STALL all request afterwards. (capture screenshot updated...

#304 and #305 fixed the issue for STM32 FSDev, will need to do more tests with other mcu :)

@pigrew yeah, there is a different issue with stm32f4, I will check it out later when doing more tests with the rest of mcus as well.

It is useful to have the stack LOG as well, what is captured on the bus is not necessary what the DCD detect if we believe there is bug within...

@duempel I would highly suggest you to use one of the stm32f4 discovery board when trouble shooting and analyzing issue. That is to make sure we are all testing the...