实现自动发送莫尔斯电码，通过串口输入要发送的字母语句，将转化为对应的莫尔斯电码，并通过串口输出由‘-’‘.’主成的转化后的电码，在PIN12、PIN13出输出高低电平。(Automatically send Morse code, through the serial port to send the letter input statement, will be transformed into the corresponding Morse code, and through the ser