Nucleo-F303RE: PA12 pin constantly at 2v.

[deepAK47]

My nucleo f303re board was connected via USB but I was using a resistor around 2.2kohms to 5V. This was fine though and it functioned as normal but when I disconnected the pins on the MCU to move it, reconnecting it back resulted in nothing. While troubleshooting, I realised that if I connected the USB cables to the MCU's usb pins, device manager was showing an unknown usb device even without any resistors in place. This did not happen before while it was working and I realised this was due to PA12, DP, which was the pin pulled high, is now constantly at 2V when the MCU powered on. Now I am not sure if this is normal but I am quite confident in saying that this is not normal and is the reason this is not working anymore. If it's helpful, I know PA12 is at 2v because I measured this with a multimeter. 

I suspect that whatever I had done cause damage to PA12 and the usb board is fried. Is this theory wrong or is there no hope for this board. Perhaps there is a way to use other pins for the usb?

[TDK]

This board only has one USB port which is connected to the onboard st-link, not the STM32F303 chip on the board. I understand you've added a secondary USB connector pigtailed to the PA11/PA12 pins?

> I was using a resistor around 2.2kohms to 5V

Why? The PA11/PA12 USB pins don't need an external pullup and certainly not to 5 V.

There are no alternative pins for USB.

If you initialize PA12 as a GPIO output and toggle it, does it toggle between 0 V and 3.3 V? Toggle an LED at the same time so you know the code is running. If not, chip is probably dead.