Resolved! HAL_UART_Transmit() with HAL_UART_Receive_IT() fails if RX when TX not completed.
I used to send AT command to a module with HAL_UART_Transmit():void send_uart(char * buffer) { uint16_t buffer_size = strlen(buffer); uint8_t CRLFbuff[] = "\r\n"; HAL_UART_Transmit(&hlpuart1, CRLFbuff, 2, 0xFF); // ok HAL_UART_Transmit(&hlpuart1...