1 /**
  2  * filename: gps.c
  3  * author: Suzkfly
  4  * date: 2021-08-21
  5  * platform: S3C2416
  6  * 编译时要加-lm
  7  */
  8  
  9 #include <stdio.h>
 10 #include <string.h>
 11 #include <math.h>
 12 #include <stdlib.h> /* 必须要包含stdlib.h，不然编译能通过，运行也不会报错，但atof函数运行的结果是错误的 */
 13 #include "uart.h"
 14 
 15 /**
 16  * \brief 从GPS/北斗模块中得到经纬度
 17  *
 18  * \param[in] fd：打开的串口设备的文件描述符
 19  * \param[out] p_lon：得到的经度
 20  * \param[out] p_lat：得到的纬度
 21  *
 22  * \retval 成功返回0，失败返回-1
 23  */
 24 int get_gps (int fd, char *p_lon, char *p_lat)
 25 {
 26     char buf[256] = { 0 };
 27     int  ret = 0;
 28     FILE *p_file = NULL;
 29     char *p_tmp = NULL;
 30     char lon_tmp[32] = { 0 };
 31     char lat_tmp[32] = { 0 };
 32     double d_lon = 0;
 33     double d_lat = 0;
 34     double d_tmp1 = 0;
 35     double d_tmp2 = 0;
 36     
 37     if ((p_lon == NULL) || (p_lat == NULL)) {
 38         return -1;
 39     }
 40     
 41     /* 文件描述符转文件流指针，为了方便获取一行数据 */
 42     p_file = fdopen(fd, "r");
 43     
 44     while (1) {
 45         p_tmp = fgets(buf, sizeof(buf), p_file);    /* 获取一行数据 */
 46         if (p_tmp == NULL) {
 47             continue;
 48         }
 49         
 50         if (strstr(buf, "$GNGGA") || strstr(buf, "$GPGGA")) {
 51             strtok(buf, ",");
 52             strtok(NULL, ",");
 53             p_tmp = strtok(NULL, ",");  
 54             strcpy(lat_tmp, p_tmp);   /* 第3次strtok得到纬度（度分格式） */
 55             
 56             strtok(NULL, ",");
 57             p_tmp = strtok(NULL, ",");
 58             strcpy(lon_tmp, p_tmp);   /* 第5次strtok得到经度（度分格式） */
 59             break;
 60         } else if (strstr(buf, "$GNRMC") || strstr(buf, "$GPRMC")) {
 61             strtok(buf, ",");
 62             strtok(NULL, ",");
 63             strtok(NULL, ",");
 64             p_tmp = strtok(NULL, ",");  
 65             strcpy(lat_tmp, p_tmp);   /* 第4次strtok得到纬度（度分格式） */
 66             
 67             strtok(NULL, ",");
 68             p_tmp = strtok(NULL, ",");
 69             strcpy(lon_tmp, p_tmp);   /* 第6次strtok得到经度（度分格式） */
 70             break;
 71         }
 72     }
 73     
 74     /* 将度分格式转换为度格式 */
 75     d_lon = atof(lon_tmp);
 76     d_lat = atof(lat_tmp);
 77     d_lon /= 100;
 78     d_lat /= 100;
 79     
 80     d_tmp1 = floor(d_lon);
 81     d_tmp2 = d_lon - d_tmp1;
 82     d_tmp2 *= 100;
 83     d_tmp2 /= 60;
 84     d_lon = d_tmp1 + d_tmp2;
 85     
 86     d_tmp1 = floor(d_lat);
 87     d_tmp2 = d_lat - d_tmp1;
 88     d_tmp2 *= 100;
 89     d_tmp2 /= 60;
 90     d_lat = d_tmp1 + d_tmp2;
 91         
 92     sprintf(p_lon, "%f", d_lon);
 93     sprintf(p_lat, "%f", d_lat);
 94     
 95     return 0;
 96 }
 97 
 98 /**
 99  * \brief example
100  */
101 int main(int argc, const char *argv[])
102 {
103     int fd = 0;
104     int ret = 0;
105     int pid = 0;
106     char buf[128] = { 0 };
107     int len = 0;
108     int i = 0;
109     char lon[32] = { 0 };
110     char lat[32] = { 0 };
111     
112     /* 打开串口设备 */
113     fd = uart_open(UART_DEV_PATH);
114     if (fd < 0) {
115         printf("open %s failed\n", UART_DEV_PATH);
116         return -1;
117     }
118 
119     /**
120      * 配置串口：
121      * 波特率：BAUD_RATE
122      * 数据位：8
123      * 校验  ：无校验
124      * 停止位：1
125      * 流控  ：无流控
126      */
127     ret = uart_set(fd, BAUD_RATE, 8, 'n', 1, 'n');
128     if (ret == -1) {
129         perror("uart set failed\n");
130         return -1;
131     }
132     
133     /* 得到GPS/北斗模块的经纬度 */
134     ret = get_gps(fd, lon, lat);
135     if (ret != 0) {
136         perror("get_gps error\n");
137         return -1;
138     }
139     
140     printf("Original Longitude = %s\n", lon);
141     printf("Original Latitude = %s\n", lat);
142     
143     return 0;
144 }