oFono support for the Telit GC864-QUAD V2 serial port GSM/GPRS modem

oFono support for the Telit GC864-QUAD V2 serial port GSM/GPRS modem

[Markus Hubig]

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Hello @all,

I'm new here and I'm in the process of developing a Embedded Linux datalogger
appliance. At the moment I'm evaluating the modem part of it, and we are
looking forward to use the Telit GC864-QUAD V2 serial port GSM/GPRS modem with
oFono.

Unfortunately I couldn't find much "getting started" information for oFono, but
by reading throughout the old posts on this list I gathered at least some.
Please correct me if I get things wrong:

1. The one-and-only way to tell oFono to use a modem is by udev rules like
   this:

    KERNEL=="ttyUSB0", ENV{OFONO_DRIVER}="calypso"

2. Serial port GPRS modems like the Telit GC864 are not supported
   out-of-the-box, so one has to write a special modem driver for it.

3. Since this modem supports CMUX multiplexing with the 3GPP 27.010 standard,
   I can use 'GAtMux' like it's done in 'plugins/calypso.c'.

4. There is a telit modem driver, but this is only for the UC864 UMTS modem
   which is connected via USB.

So in order to write a driver to support the GC864, what would be a good
starting point? Add support for serial port CMUX to the telit driver?

Looking forward for some advice ...

Cheers, Markus

Re: oFono support for the Telit GC864-QUAD V2 serial port GSM/GPRS modem

[Denis Kenzior]

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Hi Markus,

On 10/17/2012 06:28 AM, Markus Hubig wrote:
> Hello @all,
>
> I'm new here and I'm in the process of developing a Embedded Linux datalogger
> appliance. At the moment I'm evaluating the modem part of it, and we are
> looking forward to use the Telit GC864-QUAD V2 serial port GSM/GPRS modem with
> oFono.
>
> Unfortunately I couldn't find much "getting started" information for oFono, but
> by reading throughout the old posts on this list I gathered at least some.
> Please correct me if I get things wrong:
>
> 1. The one-and-only way to tell oFono to use a modem is by udev rules like
>     this:
>
>      KERNEL=="ttyUSB0", ENV{OFONO_DRIVER}="calypso"

Not the 'only' way, but that is the preferred way.  The KERNEL== line 
tells udev the device to use and OFONO_DRIVER part tells what modem 
driver to use (e.g. one from plugins/)

>
> 2. Serial port GPRS modems like the Telit GC864 are not supported
>     out-of-the-box, so one has to write a special modem driver for it.

We do not have a 'generic' driver.  While it is tempting to think that 
27.007 is enough to drive any modem, in practice that is not the case. 
At least we have tried and failed ;)  So yes, your statement is correct.

>
> 3. Since this modem supports CMUX multiplexing with the 3GPP 27.010 standard,
>     I can use 'GAtMux' like it's done in 'plugins/calypso.c'.

Correct.

>
> 4. There is a telit modem driver, but this is only for the UC864 UMTS modem
>     which is connected via USB.

Correct.

>
> So in order to write a driver to support the GC864, what would be a good
> starting point? Add support for serial port CMUX to the telit driver?
>

I would create a brand new modem driver, perhaps using calypso as the 
starting point and go from there.

> Looking forward for some advice ...
>

IRC is also a good place to get (quick) questions answered.

Regards,
-Denis

Re: oFono support for the Telit GC864-QUAD V2 serial port GSM/GPRS modem

[Denis Kenzior]

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Hi Markus,

On 10/17/2012 02:13 PM, Markus Hubig wrote:
> On Wed, Oct 17, 2012 at 08:34:21AM -0500, Denis Kenzior wrote:
>> On 10/17/2012 06:28 AM, Markus Hubig wrote:
>>> 1. The one-and-only way to tell oFono to use a modem is by udev rules like
>>>    this: KERNEL=="ttyUSB0", ENV{OFONO_DRIVER}="calypso"
>>>
>> Not the 'only' way, but that is the preferred way.  The KERNEL==
>> line tells udev the device to use and OFONO_DRIVER part tells what
>> modem driver to use (e.g. one from plugins/)
>
> e.g. means there are other places where drivers can be found. What exactly
> makes some blob.c a oFono driver? And what's the minimal API I have to
> implement to make a working driver?
>

No, modem drivers are only found in plugins/.  However, there are other 
ways of creating modems besides udev.  However, that is not really 
relevant to this discussion.

The bare minimum API would be probe and remove.  However, that is not 
very useful :)

>>> So in order to write a driver to support the GC864, what would be a good
>>> starting point? Add support for serial port CMUX to the telit driver?
>>>
>> I would create a brand new modem driver, perhaps using calypso as
>> the starting point and go from there.
>
> Hm OK i'll give it at try. But the few docs I found refer havily to the simple
> oFono-API but were can I find it? Inside doc's?
>

The docs are referring to application APIs which are exposed via D-Bus. 
  These are found in the doc/ directory.  There isn't a howto / tutorial 
on how to write a brand new modem driver, however just about everything 
can be figured out by poking around in plugins/.

>>> Looking forward for some advice ...
>>>
>> IRC is also a good place to get (quick) questions answered.
>
> Unfortunately every time I'm on IRC everybody else seems to be asleep ... ;-(
>

Maybe you're in the wrong hemisphere? :)  Most of the (still active) 
people are in the U.S. timezones.

Regards,
-Denis

Re: oFono support for the Telit GC864-QUAD V2 serial port GSM/GPRS modem

[Markus Hubig]

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On Wed, Oct 17, 2012 at 08:34:21AM -0500, Denis Kenzior wrote:
> On 10/17/2012 06:28 AM, Markus Hubig wrote:
> >1. The one-and-only way to tell oFono to use a modem is by udev rules like
> >   this: KERNEL=="ttyUSB0", ENV{OFONO_DRIVER}="calypso"
> >
> Not the 'only' way, but that is the preferred way.  The KERNEL==
> line tells udev the device to use and OFONO_DRIVER part tells what
> modem driver to use (e.g. one from plugins/)

e.g. means there are other places where drivers can be found. What exactly
makes some blob.c a oFono driver? And what's the minimal API I have to
implement to make a working driver?

> >So in order to write a driver to support the GC864, what would be a good
> >starting point? Add support for serial port CMUX to the telit driver?
> >
> I would create a brand new modem driver, perhaps using calypso as
> the starting point and go from there.

Hm OK i'll give it at try. But the few docs I found refer havily to the simple
oFono-API but were can I find it? Inside doc's?

> >Looking forward for some advice ...
> >
> IRC is also a good place to get (quick) questions answered.

Unfortunately every time I'm on IRC everybody else seems to be asleep ... ;-(

Thank you, Markus