通过串口操作GPRS模块的编程

/* ********************************************************************************
 * File  : gprs_test.c
 * Author : YangShuo
 * Data  : 2009-10-14
 * Function : this is a simple test of sending a short message via GPRS module
 * *******************************************************************************/

#include
#include
#include
#include
#include
#include
#include
#include
#include

#define TTY_NAME  "/dev/ttyS0"
#define BUF_SIZE 1024

#define CMD_CMGF "AT+CMGF=1\r"
#define CMD_CMGS "AT+CMGS=\"[phone]\"\r"
#define DEFAULT_MSG "Welcome To Ubuntu9.04!\x1a"

static volatile int tty_fd; //file descriptor of serial port

/******************************************
 * Function  : set the parameter of UART
 * return -1 : Failed
 * return 0  : Success
******************************************/
int set_tty_option(int fd, int nSpeed, int nBits, char nEvent, int nStop)
{
 struct termios new_tio, old_tio;

 if (tcgetattr(fd, &old_tio) != 0) //save the old parameter
 {
  perror("Setup Serial 1");
  return -1;
 }
 
 bzero(&new_tio, sizeof(new_tio));
 new_tio.c_cflag |= CLOCAL | CREAD; //set local mode and enable recevie function
 new_tio.c_cflag &= ~CSIZE;  //mask the character size bits

 switch (nBits)
 {
  case 7:  new_tio.c_cflag |= CS7; break; //data: 7bits
  case 8:  new_tio.c_cflag |= CS8; break; //data: 8bits
  default: break;
 }

 switch (nEvent)
 {
  case 'O':  //奇校验
   new_tio.c_cflag |= PARENB;
   new_tio.c_cflag |= PARODD;
   new_tio.c_iflag |= (INPCK | ISTRIP);
   break;
  case 'E':  //偶校验
   new_tio.c_iflag |= (INPCK | ISTRIP);
   new_tio.c_cflag |= PARENB;
   new_tio.c_cflag &= ~PARODD;
   break;
  case 'N':  //无校验
   new_tio.c_cflag &= ~PARENB;
   break;
 }

 switch (nSpeed)  //set the Baudary
 {
  case 2400:
   cfsetispeed(&new_tio, B2400);
   cfsetospeed(&new_tio, B2400);
   break;
  case 4800:
   cfsetispeed(&new_tio, B4800);
   cfsetospeed(&new_tio, B4800);
   break;
  case 9600:
   cfsetispeed(&new_tio, B9600);
   cfsetospeed(&new_tio, B9600);
   break;
  case 115200:
   cfsetispeed(&new_tio, B115200);
   cfsetospeed(&new_tio, B115200);
   break;
  case 460800:
   cfsetispeed(&new_tio, B460800);
   cfsetospeed(&new_tio, B460800);
   break;
  default:
   cfsetispeed(&new_tio, B9600);
   cfsetospeed(&new_tio, B9600);
   break;
 }

 if (nStop == 1)  //set the one bit stop
 {
  new_tio.c_cflag &= ~CSTOPB;
 }
 else if (nStop == 2)
 {
  new_tio.c_cflag |= CSTOPB;
 }

 new_tio.c_cc[VTIME] = 0;
 new_tio.c_cc[VMIN] = 0;

 tcflush(fd, TCIFLUSH);  //refresh received data buf don't read them
 if (tcsetattr(fd, TCSANOW, &new_tio) != 0)
 {
  perror("serial port set error.");
  return -1;
 }

 printf("serial port set done!\n");

 return 0;
}

/***********************************************
 * Function : intialize serial port
 * Return -1 : Failed
 * Return 0 : Success
***********************************************/
int init_tty(void)
{
 if ((tty_fd = open(TTY_NAME, O_RDWR)) == -1)
 {
  perror("open serial port failed.");
  return -1;
 } 

 set_tty_option(tty_fd, 115200, 8, 'N', 1);
}

/***********************************************
 * Function : intialize serial port
 * Return -1 : Failed
 * Return 0 : Success
***********************************************/
int send_message(const char *text)
{
 char buf_cmd[BUF_SIZE] = {0};
 char buf_rcv[BUF_SIZE] = {0};

 int nread;
 init_tty();

 write(tty_fd, CMD_CMGF, strlen(CMD_CMGF));
 sleep(1);
 nread = read(tty_fd, buf_rcv, BUF_SIZE);
 sleep(1);
 printf("nread = %d,CMD_CMGF rcv: %s\n", nread, buf_rcv);

#if 1
 write(tty_fd, CMD_CMGS, strlen(CMD_CMGS));
 sleep(1);
 read(tty_fd, buf_rcv, BUF_SIZE);
 sleep(1);
 printf("CMD_CMGS rcv: %s\n", buf_rcv);

 write(tty_fd, DEFAULT_MSG, strlen(DEFAULT_MSG));
 sleep(2);

 printf("finish sending message.\n");
#endif
 close(tty_fd);

 return 0;
}

int main()
{
 send_message("hello world!");

 return 0;
}