USB DP-DM Pins

[SARTHAK KELAPURE]

Posted on April 11, 2018 at 06:49

I am using STM32L072 on my custom board. I connected DP DM pins on USB connector directly to the DP DM pins on the MCU. I was hoping it gives me a DEBUG UART but it didn't work that way. What could be the problem?

[Tesla DeLorean]

Posted on April 11, 2018 at 07:13

Did you load any software onto the part? Is BOOT0 pulled HIGH?

Check VDDA and NRST levels.

[SARTHAK KELAPURE]

Posted on April 11, 2018 at 07:59

I flashed a 'HELLO WORLD' firmware which prints HELLO WORLD on UART. The boot0 pin is not pulled HIGH.

[Tesla DeLorean]

Posted on April 11, 2018 at 08:03

Ok, so unless you software implements a USB device the pins will do nothing. With BOOT0 pulled High it should come up as a USB DFU device if I'm looking at the right App Note.

The Debug UART of the DISCO/NUCLEO boards comes from the ST-LINK device