connectionMgr/inc/modemUtils.h File Reference

connectionMgr - provide wireless modem related utilities (e.g. signal strength) More...

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Defines
#define	BUF_LEN   256
Functions
int	get_modem_signal_strength ()

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Detailed Description

connectionMgr - provide wireless modem related utilities (e.g. signal strength)

Copyright (C) 2007 iRex Technologies BV

Definition in file modemUtils.h.

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Define Documentation

#define BUF_LEN   256

Definition at line 30 of file modemUtils.h.

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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;
}