connectionMgr/src/modemUtils.c File Reference

connectionMgr - provide wireless modem related utilities More...

#include <unistd.h>
#include <termios.h>
#include <fcntl.h>
#include <string.h>
#include "connectionMgrLog.h"
#include "modemUtils.h"

Go to the source code of this file.

Defines
#define	DEVICE_NAME   "/dev/modem"
#define	BAUD_RATE   B115200
Functions
int	get_modem_signal_strength ()

---

Detailed Description

connectionMgr - provide wireless modem related utilities

Copyright (C) 2007 iRex Technologies BV.

Definition in file modemUtils.c.

---

Define Documentation

#define BAUD_RATE   B115200

Definition at line 35 of file modemUtils.c.

#define DEVICE_NAME   "/dev/modem"

Definition at line 34 of file modemUtils.c.

---

Function Documentation

int get_modem_signal_strength

(

)

Definition at line 37 of file modemUtils.c.

{
    CN_LOGPRINTF("entry");

    int fd = open(DEVICE_NAME, O_RDWR | O_NOCTTY);

    if (fd < 0)
    {
        CN_ERRORPRINTF("Can't open %s", DEVICE_NAME);
        return 0;
    }

    struct termios new_opt, old_opt;

    // Save original settings
    tcgetattr(fd, &old_opt);

    // Set terminal attribute
    new_opt.c_cflag = BAUD_RATE | CS8 | CLOCAL | CREAD;
    new_opt.c_iflag = IGNPAR;
    new_opt.c_oflag = 0;
    new_opt.c_lflag = 0;

    // Blocking read until 1 char arrives
    new_opt.c_cc[VMIN] = 1;
    new_opt.c_cc[VTIME] = 0;

    // Now clean the modem line and activate the settings for modem
    tcflush(fd, TCIFLUSH);
    tcsetattr(fd, TCSANOW, &new_opt);

    char buf[BUF_LEN] = "AT+CSQ?\r";
    int  len = strlen(buf);
    if (len != write(fd, buf, len))
    {
        CN_ERRORPRINTF("Can't write data to %s", DEVICE_NAME);
        return 0;
    }

    len = read(fd, buf, BUF_LEN);

    if (strstr(buf, "\r\nOK\r\n") == 0)
    {
        // Modem returned error
        CN_ERRORPRINTF("Modem returned error for command AT+CSQ?");
        return 0;
    }

    int rssi = 0, fer = 0;
    sscanf(buf, "\r\n+CSQ: %d, %d\r\n", &rssi, &fer);

    // Restore original settings
    tcsetattr(fd, TCSANOW, &old_opt);
    close(fd);
    return rssi;
}