Not sure why I cannot enter UARTn_IRQHandler
I have three UARTs on the board, all passed the loopback test (wire the tx and rx pin together on the same UART)Then I connect UART 1 to UART2 while UART 1 is transmitter and UART2 is receiver.UART 1 is using HAL_UART_Transmit() to send data to UART2...