Hi,
I assume you are looking at a 3G modem that interfaces and is powered by
USB interface. There are a number of issues you have to resolve:
3G modems can draw can draw quite a bit of current. The current consumption
is variable and depends upon modem activity and 3G signal level. It can
exceed the BBB USB port current limit on the BBB. So you may need a USB hub
to power the modem. As an example the Sierra wireless modem I used on the
last project could draw up to 600 MA when attempting to register on the 3G
network.
*Angstrom by default uses connman for network management and ofono for
modem management*. Documentation for these tools is rather sparse and
terse. Depending upon the modem you intend to use and your networking
requirements, it is likely that you will have difficultly using
connman/ofono. I have found it easier to disable connman:
systemctl daemon-reload
systemctl stop connman.service
systemctl disable connman.service
And then start networking using:
/etc/init.d/networking start
To manage the modem connection you can then use pppd in the traditional
manner. It does work well. The exact method of setting up PPP depends upon
your modem and carrier. The PPP manual pages are more than adequate.
Alternatively you could install NetworkManager/modem-manager, which might
make the setup like a debian/ubuntu desktop.
Once you have this working you then need to consider the modem reliability.
Some modems occasionally do soft resets and drop the USB connection. This
is a problem for unattended remote operation. For my last project I
discovered that the modem would intermittently drop the USB interface when
the 3G signal level was low. This caused problems with PPP and we found it
necessary to write a helper application to shutdown PPP when the USB
connection to the modem dropped out and wait until the USB serial ports to
the modem were re-established before starting PPP again. Hopefully you
won't have such problems, but you need to do tests with low fluctuating 3G
signal levels.
Hopefully you won't experience all the problems we had.
Regards ...
On Tuesday, January 7, 2014 12:15:58 AM UTC+11, [email protected] wrote:
>
> Hello
>
> As part of a project I am working on, it is required to use a 3G modem
> connected to a Beaglebone Black as the BBB will be placed in a remote
> location.
> I have acquired Sakis3G, and attempted to use some 3G modems, but they did
> not work, and the script only told me that it was unable to connect to the
> modem (eventhough it did pick it up).
>
> Does anyone know where I can find a list of 3G modems compatible with the
> BBB, or reference me to a tutorial on how to connect to a 3G modem manually.
> One requirement I have is the modem must have a slot where a external
> antenna can be connected.
>
> Thank you in advance!
> Cornel
>
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