printf

1. 將發送字符指向debug

    int fputc(int ch, FILE *f)
    {
        HAL_UART_Transmit(&huart2, (uint8_t *)&ch, 1, 0xFFFF);
        return ch;
    }
   

2. 將接收字符指向debug

    int fgetc(FILE *f)
    {
        uint8_t  ch;
        HAL_UART_Receive(&huart2, (uint8_t *)&ch, 1, 0xFFFF);
        return  ch;
    }