2011/3/14 Jacky.Seraph Mun <jackyser...@gmail.com>:
> Anyone has ideas?
>
> Basically, the question is why I cannot write data to the device
> /dev/pts/1 after this device is taken by PPP daemon.
>
> Thanks
>
> 2011/3/11 Jacky.Seraph Mun <jackyser...@gmail.com>:
>> Hello,
>>
>>
>> I use the virtual channel daemon and the multiplex mode to create 2
>> channels to connect to GSM modem. One is for AT command and the other
>> one is for gprs connection.
>> The moment the APN is set, it will try to switch to data mode on the
>> GPRS channel by sending some related AT commands and start the PPP
>> daemon with it. Then the ppp net device is created and i am able to
>> send and receive data by java socket over this device.
>>
>> But when I try to disconnect the gprs connection by changing APN, I
>> got a problem that I can't send any at command to GPRS channel and
>> always get writing error code 11 (EAGAIN).
>>
>> Actually most of my code is based on freerunner froyo.
>>
>> My GSM modem is SIM900A.
>>
>> The gprs channel is opened by
>>
>>
>> fd_gprs = open ("/dev/pts/1", O_RDWR | O_NONBLOCK);
>> if ( fd_gprs >= 0 ) {
>> struct termios ios;
>> tcgetattr(fd_gprs, &ios);
>> ios.c_lflag = 0;
>> cfsetispeed(&ios, B115200);
>> cfsetospeed(&ios, B115200);
>> tcsetattr(fd_gprs, TCSANOW, &ios );
>> }
>>
>> The pppd is started with the options:
>>
>> /dev/pts/1
>> user
>> password
>> unit 1
>> noauth
>> nodetach
>> default-asyncmap
>> ipcp-accept-local
>> ipcp-accept-remote
>> usepeerdns
>> defaultroute
>>
>>
>>
>> The disconnecting AT command I sent is
>>
>>
>> int at_deactivate_modem(struct ATChannels *ATch)
>> {
>> ...
>> ioctl(ATch->s_fd, TIOCSBRK, 0);
>> ioctl(ATch->s_fd, TIOCSBRK, 0);
>> ioctl(ATch->s_fd, TIOCSBRK, 0);
>>
>> err = at_send_command_full_nolock (ATch, "+++AT", NO_RESULT,
>> NULL, NULL, CLOSE_TIMEOUT_MSEC,
>> NULL);
>>
>> /* some stacks start with verbose off */
>> err = at_send_command_full_nolock (ATch, "ATH", NO_RESULT,
>> NULL, NULL, CLOSE_TIMEOUT_MSEC,
>> NULL);
>>
>> err = at_send_command_full_nolock (ATch, "AT+CGACT=0", NO_RESULT,
>> NULL, NULL, CLOSE_TIMEOUT_MSEC,
>> NULL);
>>
>> err = at_send_command_full_nolock (ATch, "AT+CGATT=0", NO_RESULT,
>> NULL, NULL, CLOSE_TIMEOUT_MSEC,
>> NULL);
>> ...
>> }
>>
>> The err is always -1 and the errno is set to 11 accordingly.
>>
>> Could anyone has any ideas on this issue?
>>
>>
>>
>> Thanks,
>>
>> Jack
>>
>
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