USART communication

The USART2 interface available on PA2 and PA3 of the STM32 microcontroller can be connected to ST-LINK MCU, STMicroelectronics Morpho connector or to Arduino connector.

The choice can be changed by setting the related solder bridges. By default the USART2 communication between the target MCU and ST-LINK MCU is enabled in order to support Virtual Com Port for mbed (SB13 and SB14 ON, SB62 and SB63 OFF).

If the communication between the target MCU PA2 (D1) or PA3 (D0) and shield or extension board is required, SB62 and SB63 should be ON, SB13 and SB14 should be OFF.

In such case it possible to connect another USART to ST-LINK MCU using flying wires between Morpho connector and CN3.

For instance on NUCLEO-F103RB it is possible to use USART3 available on PC10 (TX) & PC11 (RX). Two flying wires need to be connected as follow:

PC10 (USART3_TX) available on CN7 pin 1 to CN3 pin RX

PC11 (USART3_RX) available on CN7 pin 2 to CN3 pin TX

And on NUCLEO-F411RE it is possible to use USART6 available on PA11 (TX) & PA12 (RX). Two flying wires need to be connected as follow:

PA11 (USART6_TX) available on CN10 pin 12 to CN3 pin RX

PA12 (USART6_RX) available on CN10 pin 14 to CN3 pin TX