EGS5 GPRS Connection Style

[Robson Pierangeli]

Hi All,

    I saw several reviews saying about making a GPRS connection via AT ^ SJNET and others by AT^SISS, AT^SISW and AT^SISE. 

   What would be the safest way to prevent me from flaws in the GPRS network? 

   In case of network failure, I need to restart (shutdown) in the module?

Thanks

Robson

[Nikita Kapitonov]

Hi Robson,

you better use Java interface to access GPRS.

In case of failure (I get an Exception), I retry several times, if that does not help, I go to airplane mode and backwards, then if nothing can fix it, I restart the module.

Nikita

2013/12/9 Robson Pierangeli <robson.p...@engflextecnologia.com.br>

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[Timo M]

Hi Robson,

Those internet AT commands AT^SISS, AT^SISW are for different purposes.
The best way is to use java connection string with

Connector.open("socket://host.com:79;bearer_type=gprs;access_point=apn_name;username=someone;password=something;timeout=40);

And reconnect with GSM network reattachment
AT+COPS=2
AT+COPS=0


Kind regards,
Timo Medvedev
-------------------------------------------------
TC65i programming, source codes and training ->  http://www.tc65.nl

Op maandag 9 december 2013 20:52:14 UTC+1 schreef Robson Pierangeli:

[Robson Pierangeli]

Nikita, thanks for the quick response. Helped me a lot in the correct firmware architecture.

Robson

[Robson Pierangeli]

Thanks for the help Timo.

Robson

[Florent]

Hi,

You should definitely use the java API, AT commands create slow and messy code.

As for the GPRS selection, I personally like the "AT^SJNET=..." way because you just have to focus on the TCP/IP layer like you would do on a computer. The low level network handling can be restricted to the starting/setup code.

About disconnection, it really helps, because some mobile networks don't handle GPRS sessions correctly (they could all end-up in timeouts at midnight for example). Closing the GPRS session definitely helps. Reconnecting to the GSM network might help also. If you do a lot of connections, don't forget to close them gracefully.

I started a library (with a little help from Nikita), it's not finished yet (you should *not* use it, it's not ready yet) but you can see how APN auto-detection is just handled as one of the startup tasks ( https://github.com/fclairamb/tc65lib/blob/master/tc65libdemo/src/org/javacint/demo/StartupLoader.java#L126 ) and then other parts like HTTP performing code ( https://github.com/fclairamb/tc65lib/blob/master/tc65lib/src/org/javacint/otap/AutoUpdater.java#L145 ) don't have to take care about this.

As a general safety, your watchdog monitoring code should restart the chip when you haven't received a successful message in the last X hours from the server. This is the best failsafe mechanism in case of failures (of any kind) because it checks the complete chain).

Best regards,