Hi, I cannot manage to receive the bytes on UART protocol on an STM32U0 when using the STLINK-V3MINIE.
The RX works properly (I can send data to the PC), so the pins are not swapped. The Vref of STLINK is 3V3, and the STLINK measures it correctly. Moreover, I can successfully program the U0 using the STLINK so I think both devices are in good shape.
The UART baud rate is 115200 b/s. I have attached an oscilloscope to observe the signal. When NOT connected to the MCU, the TX signal is clear as expected (0V as low and 3V3 as high). If I connect it the MCU, the signal is still very clear and sharp but reduced (the "low" level is about 1.65V and the high level is 3V3). The schematic is the most straightforward: no components between the STLINK and the MCU.
The firmware on STLINK is the V3J17M10.
Currently, I have solved it using another USB-serial converter (CP2102) and it works flawlessly in both directions, using interrupts, DMA and whatever firmware tricks, but I would understand why the STLINK doesn't work properly.
