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?
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
Did you load any software onto the part? Is BOOT0 pulled HIGH?
Check VDDA and NRST levels.
I flashed a "HELLO WORLD" firmware which prints HELLO WORLD on UART. The boot0 pin is not pulled HIGH.
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