voidread_serial_data(){//寻找数据包起始同步字节，2个if(ReadOneByte() == 0xAA)//先读一个    {if(ReadOneByte() == 0xAA)//读第二个      {payloadLength = ReadOneByte();//读取第三个，数据包字节的长度if(payloadLength == 0x20)//如果接收到的是大包数据才继续读取，小包数据则舍弃不读取        {generatedChecksum = 0; //校验变量清0       for(inti = 0; i<payloadLength; i++)//连续读取32个字节          {  payloadData[i] = ReadOneByte();//读取指定长度数据包中的数据generatedChecksum += payloadData[i];//计算数据累加和          }                   checksum = ReadOneByte();//读取校验字节//校验generatedChecksum = (~generatedChecksum)&0xff;       //比较校验字节if(checksum == generatedChecksum)//数据接收正确，继续处理          {    signalquality = 0;//信号质量变量            attention = 0;    //注意力值变量//赋值数据signalquality = payloadData[1];//信号值            attention = payloadData[29];//注意力值            meditation = payloadData[31];//放松度值if(!DEBUGOUTPUT)         //打印信号质量            {Serial2.print("SignalQuality: ");Serial2.print(signalquality, DEC);//打印注意力值Serial2.print("Attation: ");Serial2.print(attention, DEC);//打印放松度值