Ux_Device_CDC_ACM Application - UART

[Babaluis]

I am trying to get the Ux_Device_CDC_ACM application working on the NUCLEO-U5A5ZJ-Q development board.  I see the VCOM port activated on the PC but how do I get the UART port?  It appears that the application writes from the UART port to the VCOM port and vice-versa, but it is not clear how to connect the UART.  Do I use an FTDI cable somehow? Or is it on the USB-C connector?

[FBL]

Hi @Babaluis & welcome to ST Community :) 

Thank you for your question! Typically, this example emulates the USB - UART bridge. 

UART port is available on the NUCLEO-U5A5ZJ-Q board and can be accessed via the appropriate UART pins (TX and RX). UART GPIO configuration for this example is here 

You don't need an FTDI cable. In this example you can ping pong UART data between STLink VCP and User VCP. You can open two hyperterminals (USB com port and UART com port(USB STLink VCP)) to send/receive data to/from host from/to device.

[Babaluis]

When I open Device Manager I only see one com port: "STLink Virtual COM Port (COM4)".  How do I get the other com port?

[FBL]

Hi @Babaluis 
Can you check the clock selected for USB?  Which board revision do you have? MB1549-U5A5JQ-C02?

[Babaluis]

I have board revision C04.  The clock to OTG HS is HSE 16 MHz.

[Babaluis]

The statement in stm32u5xx_hal_msp.c line 278 is "__HAL_RCC_SYSCFG_CLK_ENABLE();"

[Babaluis · Accepted solution]

I got it working. The problem was that I did not see the instruction to connect the USB connector CN15 as well as the STLINK connector CN1. Both connectors must be plugged into the PC for both COM ports to show up.

Thank you for your help.