gps-.c

linux gps rs232 yuanma

============================================
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <fcntl.h>   //文件控制定义
#include <unistd.h>    //Unix 标准函数定义
#include <termios.h>  //PPSIX 终端控制定义 //结构体termios,  
struct  termios{ unsigned short c_iflag;  //输入模式标志   
unsigned short c_cflag;  //控制模式标志 
unsigned short c_lflag;  //本地模式标志 
unsigned char c_line;   //控制协议 
unsigned char c_cc[NCCS]  //控制字符}
#include <errno.h>      //错误号定义

static int g_nErrorCode = 0;

    char TestMode4[15] =            //切换sirf至mode 4
       {0xA0, 0xA2,
        0x00, 0x07,     // payload length
        0x96,            // 150,switch operation mode
        0x1E ,0x54,     // test mode 4
        0x00, 0x14,        // SvID on simulator (21..) MUST match simulator
        0x00, 0x0A,        // Period, tracking period 10 sec
        0x01, 0x15,        // checksum  --> (add all payload) % 0x07ff
        0xb0, 0xb3};
unsigned char SwitchToSirf[] =             //切回nmea协议命令
      { 0xa0, // KILL THIS BYTE
       0xa2,0x00,0x18, // start sequence and payload length
       0x81, // message ID dec 129, switch to NMEA
       0x02, // Mode
       0x01,0x01, // GGA
       0x00,0x01, // GLL
       0x01,0x01, // GSA
       0x05,0x01, // GSV
       0x01,0x01, // RMC
       0x00,0x01, // VTG
       0x00,0x01, // MSS
       0x00,0x01, // unused
       0x00,0x01, // ZDA
       0x00,0x01, // unused
       0x12,0xc0, // baudrate 4800
       0x01,0x67, // msg checksum
       0xb0,0xb3  // end sequence
      };

//切换至sirf协议的nmea报文（两种报文对应波特率不同）
    char *SwitchToNMEA   =  "$PSRF100,0,57600,8,1,0*XX\r\n";
    char *SwitchToNMEA4800   =  "$PSRF100,0,4800,8,1,0*XX\r\n";
    //char *pMsg;
     

int  GPS_InfoProcess(char* info)
{
    int dwCNOMean = 0;
    dwCNOMean=*((unsigned short*)&info[23]);    
    printf("CNOMean = %d\n", dwCNOMean);
    return dwCNOMean;
}


static int GPS_DataReceive(int nProtocol)
{     
       

       struct termios options;  //终端特性变量定义及初始化
       int fd, Rt, recv_len, fd_sel;
       //fd_set fd_gps, fd_sel;
       struct timeval tv;  //定义超时控制结构 
             fd_set fds;   //文件描述符集合变量
       char buf[1024];
       int i, nReadIndex = 0, bHeaderOK = 0, nWriteIndex = 0;
      
       static char  m_sMessage_ID46Buffer[60];
        
        const char acMessge2E[5] = { 0xa0, 0xa2, 0x00, 0x33, 0x2e };  // 2E Test Mode 3/4 - Message ID 46
       long nSeconds = time(NULL);
       printf("Start Time: %d\n", nSeconds);
       long nBegin;
        
        fd = open("/dev/ttyS1", O_RDWR); //打开串口
        printf("Get fd: %d\n", fd);
        if (-1 == fd)  // 不能打开串口一
        { 
               perror("Can't Open Port!\n");
               g_nErrorCode = 1;
        }
        
         
        if (tcgetattr ( fd, &options) == -1)   //获取当前设备方式
        {
            printf("Cannot get GPS configuration!\n");
            g_nErrorCode = 2;
            return 0;
        }
        cfsetispeed(&options,B4800); //设置输入为4800Bps
                cfsetospeed(&options,B4800); //设置输出为4800Bps
                options.c_lflag &= ~(ICANON | ECHO | ECHOE | ISIG); 
                options.c_oflag &= ~OPOST; 
        if (tcsetattr ( fd, TCSANOW, &options) == -1)    //设置波特率
        {
            printf("Cannot set GPS configuration!\n");
            g_nErrorCode = 3;
            return 0;
        }
        
        
    
        tv.tv_sec = 5;  
        tv.tv_usec = 0;

        FD_ZERO(&fds);   
        FD_SET(fd, &fds);  

    /*fd_sel = select(fd+1, &fds, NULL, NULL, &tv);
    if (fd_sel == 0)
    {
        printf("Select Failed!\n");
        g_nErrorCode = 4;      
        return 0;            
    }*/
    
    
    
    Rt = write(fd, SwitchToSirf, strlen(SwitchToSirf));

    if(Rt == -1)
    {   
          printf("Switch to Sirf failed!\n");
          g_nErrorCode= 5 ;
          return 0;
    }
    printf("Switch OK\n");
    nBegin = time(NULL);
    while (time(NULL) - nBegin < 1);
    
    
    Rt = write(fd, TestMode4, strlen(TestMode4));

    if(Rt == -1)
    {   
          printf("Switch test mode 4 failed!\n");
          g_nErrorCode = 6;
          return 0;
    }
    printf("Mode 4 OK\n");
    nBegin = time(NULL);
    while (time(NULL) - nBegin < 1);
    
        while(time(NULL) - nSeconds <= 35)
    {
                    //printf("Time: %d\n", time(NULL));
                    if (FD_ISSET(fd, &fds))
                    {
                        printf("Data in\n");
                          recv_len = read(fd, buf, 200);
                          printf("%s\n", buf);
                          printf("length: %d", recv_len);
                        if (recv_len > 0)
               {
                        for (i = 0;i < recv_len;i++)
                        {
                           m_sMessage_ID46Buffer[i + nWriteIndex] = buf;
                           //nWriteIndex++;
                        }
                            nWriteIndex += recv_len;
                
                        while (!bHeaderOK && (nReadIndex != nWriteIndex))
                        {
                           if (m_sMessage_ID46Buffer[nReadIndex] == acMessge2E[nReadIndex])
                           {
                                nReadIndex++;
                                if (nReadIndex == 5)
                                   bHeaderOK = 1;
                            }
                            else {
                               for (i = 0;i < nWriteIndex - nReadIndex + 1;i++)
                                               {
                                                  m_sMessage_ID46Buffer = m_sMessage_ID46Buffer[nReadIndex + i];    
                                               }
                                               nReadIndex = 0;
                                               nWriteIndex = i;
                                               break;
                            }
                         }
                           if (nWriteIndex - 8 >= 0x33)
                           {
                                   if (m_sMessage_ID46Buffer[58] != 0xB3 || m_sMessage_ID46Buffer[57] != 0xB0)
                                {                            
                                                           printf("Receiving Error gps data.\n");
                                                           g_nErrorCode = 7;
                                    break;
                                 }
                               else 
                              {
                                     return  GPS_Info_Process(m_sMessage_ID46Buffer) >= 43.5;
                                 }
                           }
                            }
            }
            //printf("No data\n");
            }

    if(time(NULL) - nSeconds > 35) g_nErrorCode = 8; // timeout
    sleep(1);
    close(fd);
    return 0;
}

int main(int argc,char *argv[])
{
    int nProtocol = 0;
    if (argc >= 1) 
    {
        if (argv[0] == "nmea") nProtocol = 1;
        else if (argv[0] == "sirf") nProtocol = 0;
    }
    printf("---GPS Dump Test---\n");
    printf("---GPS Dump Test: %s ---\n", GPS_DataReceive(nProtocol) ? "SUCCEEDED" : "FAILED");
    return g_nErrorCode;
}