Qt5下串口对高频率自发性数据的接收及处理方法

       在项目中需要用Qt5.9采集仪表中的数据，仪表是以200Hz的频率主动向外连续发送数据，发送频率很高，而且主动发送，不需要软件发送一次，再读取一次，而是软件直接读取。这种直接连续读取，有两个关键点：1）如何从接收buffer里面查找出所需的数据帧；2）每次接收的数据buffer里面会有很多帧，如何存起来，每一帧的去解析，处理。

       整个程序分为：1）主程序下串口接收信号与串口接收函数connect部分；2）串口定时器启动函数serial_timerstart()；3）串口读取函数部分；

一、主程序下串口接收信号与串口接收函数connect部分

 timer = new QTimer();
 QObject::connect(&serial,&QSerialPort::readyRead,this,&Trajectory::serial_timerstart);
 QObject::connect(timer,&QTimer::timeout,this,&Trajectory::serial_readyRead);

采用定时器，周期性读取串口数据。

二、串口定时器启动函数serial_timerstart()；

void Trajectory::serial_timerstart()
{
   timer->start(3);//启动定时器，接收3毫秒数据（根据情况设定）
   buffer.append(serial.readAll());
  
}

三、串口读取函数部分；

void Trajectory::serial_readyRead()
{

    unsigned  char recvdata[255];
    int recvnum=0;

    timer->stop();//停止定时器，

   qDebug() << "receive(buffer.toHex()):= " <<buffer.toHex();
   qDebug() << "receive(buffer.toHex().size()):= " <<buffer.toHex().size();

    att_mg200[0]=0;
    att_mg200[1]=0;
    att_mg200[2]=0;
    att=att_mg200;
    QByteArray buffer0 = "55aa";
    QByteArray buffer1;
    int index=0;
    int recvframenum=0;
     QVector<QByteArray>vect1;
      //从开头搜索"55aa"
       while((index = buffer.toHex().indexOf(buffer0,index))<buffer.toHex().size())
     {
          buffer1 = buffer.toHex().mid(index,80);  //获取55aa***
         if(buffer1.size()==80)
         {
           vect1.push_back(buffer1);
           index=index+80;
           recvframenum++;
          qDebug() << "receive(buffer1):= " <<buffer1;
         }
         else
         {
           break;
         }

      }



    for(int t=0;t<255;t++)
     {
        recvdata[t]=0;
     }


  for(int j=0;j<recvframenum;j++)
    {
      recvnum=0;
      qDebug() << "recvframenum:= " <<recvframenum;
      for(int i=0;i<vect1[j].size();i++) //ASCII码字符转为16进制
          {

              if(vect1[j][i]>='0'&&vect1[j][i]<='9')
                  recvdata[i]=vect1[j][i]-48;
              else if(vect1[j][i]>='A'&&vect1[j][i]<='F')
                  recvdata[i]=vect1[j][i]-65+10;
              else if(vect1[j][i]>='a'&&vect1[j][i]<='f')
                  recvdata[i]=vect1[j][i]-97+10;
              else  QMessageBox::warning(NULL, QString::fromLocal8Bit("警告"), 
                    QString::fromLocal8Bit("接收数据错误"));
           }
          for(int i=0;i<vect1[j].size();i+=2)
          {
              recvdata[recvnum]=recvdata[i]*16+recvdata[i+1];
              qDebug() << "recvdata:= " <<recvdata[recvnum]<<" "<<recvnum<<" "<<i;
              recvnum++;
           }
  else if((recvnum==40)&&(recvdata[0]==85)&&(recvdata[1]==170))
    {
     //接收数据处理
        Gx=((((qint32)recvdata[10])<<24)+(((qint32)recvdata[9])<<16)+
             (((qint32)recvdata[8])<<8)+recvdata[7])*0.000001f;
        Gy=((((qint32)recvdata[14])<<24)+(((qint32)recvdata[13])<<16)+
             (((qint32)recvdata[12])<<8)+recvdata[11])*0.000001f;
        Gz=((((qint32)recvdata[18])<<24)+(((qint32)recvdata[17])<<16)+
             (((qint32)recvdata[16])<<8)+recvdata[15])*0.000001f;
        Gxh=Gxh+Gx;
        Gyh=Gyh+Gy;
        Gzh=Gzh+Gz;

        Ax=((((qint32)recvdata[22])<<24)+(((qint32)recvdata[21])<<16)+
              (((qint32)recvdata[20])<<8)+recvdata[19])*0.000001f;
        Ay=((((qint32)recvdata[26])<<24)+(((qint32)recvdata[25])<<16)+
              (((qint32)recvdata[24])<<8)+recvdata[23])*0.000001f;
        Az=((((qint32)recvdata[30])<<24)+(((qint32)recvdata[29])<<16)+
              (((qint32)recvdata[28])<<8)+recvdata[27])*0.000001f;
        Axh=Axh+Ax;
        Ayh=Ayh+Ay;
        Azh=Azh+Az;

       recvdataNum++;

       qDebug() << "recvdataNum= " <<recvdataNum;


      if(recvdataNum==6000)
      {
       imudata[0]=Gxh/6000;
       imudata[1]=Gyh/6000;
       imudata[2]=Gzh/6000;
       imudata[3]=Axh/6000;
       imudata[4]=Ayh/6000;
       imudata[5]=Azh/6000;

       qDebug() << "imudata[0]= " <<imudata[0];
       qDebug() << "imudata[1]= " <<imudata[1];
       qDebug() << "imudata[2]= " <<imudata[2];
       qDebug() << "imudata[3]= " <<imudata[3];
       qDebug() << "imudata[4]= " <<imudata[4];
       qDebug() << "imudata[5]= " <<imudata[5];


       recvdataNum=0;
       Gxh=0;
       Gyh=0;
       Gzh=0;
       Axh=0;
       Ayh=0;
       Azh=0;
    }

   }
  else
    {
     QMessageBox::warning(NULL, QString::fromLocal8Bit("警告"),QString::fromLocal8Bit("接收到无效数据"));

    }
  }
  buffer.clear();


}

四、调试记录如下：

receive(buffer.toHex()):="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"

receive(buffer.toHex().size()):= 25102
receive(buffer1):= "55aa2413740f00d9060000d00f00001cfcffffbc9afdffc748010043a795009a12b01100000000dc"
receive(buffer1):= "55aa2418740f009cf0ffffdcd1ffff39c1ffff2a7cfdff7e400100ea7d95009a12b01100000000b6"
receive(buffer1):= "55aa241d740f00c91100004fecffff1ef5fffffb77fdff6d4d0100766595009a12b01100000000ee"
receive(buffer1):= "55aa2422740f0004a2ffff036fffff7d210000a97afdff2e4301006e7795009a12b01100000000f3"
receive(buffer1):= "55aa2427740f00f310000063f5ffffd8dbffffeba4fdff15400100c03395009a12b01100000000ae"
receive(buffer1):= "55aa242c740f00649dffff35b6ffff6fe5ffff249afdff06500100ad2895009a12b01100000000f5"
receive(buffer1):= "55aa2431740f006968000051060000bb020000879efdff3e5901007d3f95009a12b0110000000034"
receive(buffer1):= "55aa2436740f00840b0000fcf0ffffcc8c00008081fdffbc2b0100626795009a12b011000000005e"
receive(buffer1):= "55aa243b740f0090ecffffd9ddffffc90a00004890fdff97440100fb5e95009a12b01100000000ee"
receive(buffer1):= "55aa2440740f00a4ddffff6afcffffa2e6ffff3f99fdffe52e0100316395009a12b01100000000ce"
receive(buffer1):= "55aa2445740f00ce8bffff7cbcffff9bd3ffff267dfdff38480100215c95009a12b0110000000084"
receive(buffer1):= "55aa244a740f0033d9ffff4fe8ffff0e530000c48dfdff70460100f95095009a12b01100000000e0"
receive(buffer1):= "55aa244f740f0086f1ffff935d0000a50e00002573fdffae470100af3995009a12b0110000000082"
receive(buffer1):= "55aa2454740f00e76900009e8affff2ff1ffffe286fdff7b4201004a4195009a12b011000000003e"
receive(buffer1):= "55aa2459740f0030d5ffff7d4100006c080000b69dfdfff34601004f3e95009a12b011000000004d"
receive(buffer1):= "55aa245e740f002fd1ffffc43e000048170000bd93fdffd14d0100a43c95009a12b01100000000b1"
receive(buffer1):= "55aa2463740f0033390000db2000008f0e0000bf79fdff34610100b45d95009a12b01100000000eb"
receive(buffer1):= "55aa2468740f0073cfffff2a6d0000be3d0000e0a5fdff4a3801006b7b95009a12b01100000000cd"
receive(buffer1):= "55aa246d740f00b82600007f28000036e9ffff69a8fdff3c3901006d7595009a12b011000000001d"
receive(buffer1):= "55aa2472740f006eebffff2bedffff74260000287cfdffe04d03901006d765009a11b014000000004d"

五、程序分析：

1）第一步，将接收的buffer转成hex，buffer.toHex()，见上面调试记录的第一组数据

2）通过while循环从接受的缓冲区中搜索所有的以”55aa“开始的数据帧，搜索到之后，将索引号开始的数据帧，后面的80个字符存入buffer1，并且判断buffer1的大小是否为80,用来排除接收的buffer.toHex()中最后搜索到不足一帧的数据（调试记录中"55aa2431740f006968"）。

3）将满足80个字符位的数据buffer1存入容器vect1,其中vect1定义：QVector<QByteArray>vect1，连续将所有搜索到的每一帧数据存入容器vect1,并且搜索索引号变更（自加80），从下一帧开始搜索。

  while((index = buffer.toHex().indexOf(buffer0,index))<buffer.toHex().size())   
{          
     buffer1 = buffer.toHex().mid(index,80);  //获取55aa***        
     if(buffer1.size()==80)
    {    
    vect1.push_back(buffer1);           
     index=index+80;        
     recvframenum++;     
    qDebug() << "receive(buffer1):= " <<buffer1;
      }        
 else                
      break;    
  }        

4）利用两个for循环将vect1的每一帧数据分别处理成16进制字节数据。例如：字符'5'的ASCII码值为53，53-48=5，字符'a'的ASCII码值为97，97-97+10=0x0a

for(int j=0;j<recvframenum;j++)
    {
      recvnum=0;
      qDebug() << "recvframenum:= " <<recvframenum;
      for(int i=0;i<vect1[j].size();i++) //ASCII码字符转为16进制
          {

              if(vect1[j][i]>='0'&&vect1[j][i]<='9')
                  recvdata[i]=vect1[j][i]-48;
              else if(vect1[j][i]>='A'&&vect1[j][i]<='F')
                  recvdata[i]=vect1[j][i]-65+10;
              else if(vect1[j][i]>='a'&&vect1[j][i]<='f')
                  recvdata[i]=vect1[j][i]-97+10;
              else  QMessageBox::warning(NULL, QString::fromLocal8Bit("警告"), QString::fromLocal8Bit("接收数据错误"));
           }
          for(int i=0;i<vect1[j].size();i+=2)
          {
              recvdata[recvnum]=recvdata[i]*16+recvdata[i+1];
             qDebug() << "recvdata:= " <<recvdata[recvnum]<<" "<<recvnum<<" "<<i;
              recvnum++;
           }

....

}

六、小结

1)利用indexOf()从字符串的开始搜索特定的字符串，并通过索引号搜索到完整的数据帧

2)利用容器vect，存放搜索的数据帧