好久没有写博客了，先从一个小小的程序开始一段新的历程吧；
最近的项目主要还是用的的是linux系统，这篇文章主要介绍如何从设置、读取BD+gps模块（um220），实际上主要是对串口（UART）的操作。
/*
* gps.c
*
* um220 test
*
* Author: Wang Zhengkai <449811900@qq.com>
*
*/
#include <stdio.h>
#include <termios.h>
#include <strings.h>
#include <string.h>
#include <stdlib.h>
#include <fcntl.h>
#include <unistd.h>
/*我用的是ubuntu的电脑测试的，使用的串口是ttyS0*/
#define DEV_NODE "/dev/ttyS0"
#define MAX_PACKET_SIZE 1024
/* Initialize serial port options */
static void setTermios(struct termios * pNewtio, int uBaudRate)
{
bzero(pNewtio, sizeof(struct termios)); /* clear struct for new port settings */
//8N1
pNewtio->c_cflag = uBaudRate | CS8 | CREAD | CLOCAL;
pNewtio->c_iflag = IGNPAR;
pNewtio->c_oflag = 0;
pNewtio->c_lflag = 0; //non ICANON
}
/*设置um220串口的波特率9600，并刷新使其立即生效*/
void um220_uart_init(int ttyFd,struct termios *oldtio,struct termios *newtio)
{
tcgetattr(ttyFd, oldtio); /* save current serial port settings */
setTermios(newtio, B9600);
tcflush(ttyFd, TCIFLUSH);
tcsetattr(ttyFd, TCSANOW, newtio);
}
/*Analysis Data of um220*/
void parseData(char *buf)
{
int nQ, nN, nB, nC;
char cX, cY, cM1, cM2;
float fTime, fX, fY, fP, fH, fB, fD;
if (buf == NULL)
{
printf("error: Can't get buf!
");
return;
}
sscanf(buf,"$GNGGA,%f,%f,%c,%f,%c,%d,%02d,%f,%f,%c,%f,%c,%f,%04d%02x",&fTime,&fX,&cX,&fY,&cY,&nQ,&nN,&fP,&fH,&cM1,&fB,&cM2, &fD, &nB, &nC);
printf("x: %c %f, y: %c %f, h %f, satellite: %d
",cX, fX, cY, fY, fH, nN);
/*cX：N or S;fX：纬度；cY：E or W；fY：经度；fH：height；nN：卫星个数*/
}
int main(void)
{
int nb,command;
int um220_fd = -1;
char newbuf[MAX_PACKET_SIZE];
char msg[20],*ret=NULL;
struct termios oldtio, newtio;
/*Open Um220 Module*/
if ((um220_fd = open(DEV_NODE, O_RDWR)) < 0) {
printf("error: Can't open serial port %s!
", DEV_NODE);
return -1;
}
/*Init Uart for Um220*/
um220_uart_init(um220_fd,&oldtio,&newtio);
/*Set Um220 options*/
printf("Please select modules of um220
");
printf("1.BD module
");
printf("2.GPS module
");
printf("3.BD+GPS module
");
if(scanf("%d",&command) != 1)
{
printf("error:input is wrong!
");
}
switch(command)
{
case 1:
memset(msg, 0, sizeof(msg));
strcpy(msg,"$cfgsys,h01");
if(write(um220_fd,msg,sizeof(msg)) < 0)
printf("Failed to set BD modules!
");
break;
case 2:
memset(msg, 0, sizeof(msg));
strcpy(msg,"$cfgsys,h10");
if(write(um220_fd,msg,sizeof(msg)) < 0)
printf("Failed to set GPS modules!
");
break;
case 3:
memset(msg, 0, sizeof(msg));
strcpy(msg,"$cfgsys,h11");
if(write(um220_fd,msg,sizeof(msg)) < 0)
printf("Failed to set BD+GPS modules!
");
break;
default:
printf("Can't identify command,set BD+GPS modules!
");
memset(msg, 0, sizeof(msg));
strcpy(msg,"$cfgsys,h11");
if(write(um220_fd,msg,sizeof(msg)) < 0)
printf("Failed to set BD+GPS modules!
");
}
for(;;)
{
/*Read Data from Um220*/
memset(newbuf, 0, 1024);
nb = read(um220_fd, newbuf, MAX_PACKET_SIZE);
if (nb == -1)
{
perror("read uart error");
return -1;
}
if ((ret=strstr(newbuf, "$GNGGA")) != NULL)
{
/*Analysis Data*/
parseData(ret);
}
sleep(1);
}
/*Recover Settings Of Serial Port*/
tcsetattr(um220_fd,TCSANOW,&oldtio);
/*Close Um220_fd*/
close(um220_fd);
return 0;
}