发送数据包到UBX协议

send packet to UBX protocol

本文关键字：UBX 协议 数据包      更新时间：2023-10-16

最近我一直在研究一个支持UBX和NEMA协议的GPS接收器。我在c++上使用串行编程。我正在尝试使用UBX协议，但似乎我只从NEMA收到。我下载了驱动程序，我想我需要先发送一个包裹通过UBX接收。有人知道链接或可以告诉我如何发送这些包，我开发的方法如下所述，我想我需要一个小命令，然后我开始阅读数据。D

void read_port(void)
{
    unsigned char c='D';

     while (c!='q')
    {
            if (read(fd, UBX_buffer, sizeof(UBX_buffer))>0)      
            {
                data = read(fd, UBX_buffer, sizeof(UBX_buffer));
            //  write(fd,&UBX_buffer,1);  // if new data is available on the serial port, print it out
      cout<<"Data on the port =  ";
      for (unsigned i =0; i< sizeof(UBX_buffer) ;i++){
        cout<<&UBX_buffer[i];  

    }
    cout<<" "<<endl;
     for (int i=0; i<fd; i++)  // Process bytes received
{
     switch(UBX_step)     //we start from zero and increment as we go through the cases
  {
  case 0:  
    if(data==0xB5)  UBX_step++;  break; // UBX sync char 1 //check for the first data packet and go to next byte

  case 1:  if(data==0x62) UBX_step++;// UBX sync char 2 //check for the second data packet and go to the next byte
    else    UBX_step=0; break;  //if first and second packets are not correct then go back and check again     
  case 2:   UBX_class=data; checksum(UBX_class); UBX_step++;  break;
  case 3:   UBX_id=data;  checksum(UBX_id);  UBX_step++; break;
  case 4:   UBX_payload_length_hi=data; checksum(UBX_payload_length_hi);  UBX_step++;  break;
  case 5:   UBX_payload_length_lo=data; checksum(UBX_payload_length_lo);  UBX_step++; break;
  case 6:         // Payload data read...
  if (UBX_payload_counter < UBX_payload_length_hi)  // We stay in this state until we reach the payload_length
    {
      UBX_buffer[UBX_payload_counter] = data;
      checksum(data);
      UBX_payload_counter++;
    }
    else
      UBX_step++; 
    break;
  case 7:   ck_a=data;  UBX_step++; break;      // First checksum byte
  case 8:   ck_b=data;                           // Second checksum byte
    // We end the GPS read...
    if((ck_a= ck_a)&&(ck_b= ck_a))   // Verify the received checksum with the generated checksum.. 
          parse_ubx_gps();               // Parse new GPS packet...

    UBX_step=0;
    UBX_payload_counter=0;
    ck_a=0;
    ck_b=0;
    GPS_timer=0; //Restarting timer...
    break;
      }
  }
            if (read(STDIN_FILENO,&c,1)>0) write(fd,&c,1);  // if new data is available on the console, send it to the serial port
    }
    close(fd);

  } // End Switch
} // End For

您可以在ublox主页下载ublox协议规范。在这里，查看cfg消息。出于测试目的，您还可以通过工具u-Center启用ubx协议。

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