Question

最近我一直致力于支持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，但似乎我只接受了NEMA。我下载了驱动程序，我想我需要先发送一个包通过UBX接收。有没有人知道一个链接或者可以告诉我如何发送这些包我开发的方法如下所述我想在开始阅读数据之前我需要一个小命令。请有人在这帮助我：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

Answer 1

在ublox主页上，您可以下载ublox协议规范。在那里，看看cfg消息。出于测试目的，您还可以通过工具u-Center启用ubx协议。

将数据包发送到UBX协议

1 个答案: