Serial Port modems - can ofono help?

Serial Port modems - can ofono help?

[Ed W]

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Hi, I have a bunch of serial to usb adaptors which will be connected to
either a GPS or a serial port modem (yes such things still exist in
use).  Can ofono help me detect whether a given serial port is connected
to a modem, gps or disconnected?

Thanks

Ed W

Re: Serial Port modems - can ofono help?

[Denis Kenzior]

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Hi Ed,

On 06/12/2011 06:30 AM, Ed W wrote:
> Hi, I have a bunch of serial to usb adaptors which will be connected to
> either a GPS or a serial port modem (yes such things still exist in
> use).  Can ofono help me detect whether a given serial port is connected
> to a modem, gps or disconnected?

Not really.  You can certainly integrate with oFono's udev detection
code for the usb serial port converter detection and automatically know
which ttys belong to the serial converter.

However, to my knowledge there is no way to know what is 'on the other
side'.  You would need to open the tty and run a few AT commands to find
out the actual device type.

If you can combine the two above parts then you might be able to detect
modem devices automatically, Marcel had a few ideas how to do this, but
nothing concrete has been done yet.

Regards,
-Denis

Re: Serial Port modems - can ofono help?

[Ed W]

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On 11/06/2011 14:30, Denis Kenzior wrote:
> Hi Ed,
> 
> On 06/12/2011 06:30 AM, Ed W wrote:
>> Hi, I have a bunch of serial to usb adaptors which will be connected to
>> either a GPS or a serial port modem (yes such things still exist in
>> use).  Can ofono help me detect whether a given serial port is connected
>> to a modem, gps or disconnected?
> 
> Not really.  You can certainly integrate with oFono's udev detection
> code for the usb serial port converter detection and automatically know
> which ttys belong to the serial converter.

Thanks could you offer me some reference to what you mean here?  ie does
ofono offer me something over and above simply a udev rule firing on the
correct subsystem (and perhaps limiting by driver name if we really want
to tighten up the rule?)

> However, to my knowledge there is no way to know what is 'on the other
> side'.  You would need to open the tty and run a few AT commands to find
> out the actual device type.

Agreed - I currently plan to gently probe any serial to usb devices to
see if they either a) chat without listening (GPS), b) raise various
modem lines high, c) respond to AT, ATI, ATCGSM, etc

A slight subtlety is that we need to allow for someone to plug in the
serial to usb adaptor without the modem powered on, and hence probing
might take an unknown amount of time (wow doesn't USB solve a lot of
issues...)

> If you can combine the two above parts then you might be able to detect
> modem devices automatically, Marcel had a few ideas how to do this, but
> nothing concrete has been done yet.

I need to implement something pretty imminently - just wondering if
ofono had something to help.  For example is there a "probe this port
and tell me what modem is on the end" feature? That way I could point it
at my suspected serial port and ask ofono to scan it?

Thanks

Ed W

Re: Serial Port modems - can ofono help?

[Denis Kenzior]

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Hi Ed,

> Thanks could you offer me some reference to what you mean here?  ie does
> ofono offer me something over and above simply a udev rule firing on the
> correct subsystem (and perhaps limiting by driver name if we really want
> to tighten up the rule?)
> 

Nope, it really doesn't.  Well besides maybe an easy integration point
with GAtChat library.

>> If you can combine the two above parts then you might be able to detect
>> modem devices automatically, Marcel had a few ideas how to do this, but
>> nothing concrete has been done yet.
> 
> I need to implement something pretty imminently - just wondering if
> ofono had something to help.  For example is there a "probe this port
> and tell me what modem is on the end" feature? That way I could point it
> at my suspected serial port and ask ofono to scan it?

Nope, there isn't anything like that.  We have plans to implement
something similar, but in the end most of our modems can be easily
detected via udev, or are on platforms with a well known configuration
(e.g. the Freerunner, etc).  So the motivation to do so is not high
right now.  If you manage to make this work nicely (either with oFono or
something else) we'd love to hear about it.

Regards,
-Denis