Support for Hayes AT Commands on Android

[Hetal]

A current product I work on supports standard modem AT commands over
the serial link. Commands such as ATD, ATH, ATV, ATQ ATE etc to either
get information from the device or seti info on the device.

The device also supports dial-up PPP connection which is typically
preceded by some AT commands when initiated from the PC - ATD for e.g.

We are looking at creating a similar device using Android and I
searched whether Android or Linux support Hayes modem AT commands over
the serial interface such as RS232 or USB and am unable to find such a
layer or component.

On Android RIL page I see it says that, "Android provides a reference
Vendor RIL, using the Hayes AT command set, that you can use as a
quick start for telephony testing and a guide for commercial vendor
RILs". But I believe this may be for interfacing with the Baseband or
Telephony layer. Is this also typically used with the serial interface
where a DTE can issue AT commands and talk to the Android device ?

I also researched Linux and it does have a basic set of AT commands
but they are not modem related and serve a different purpose - e.g.
atq lists the user's pending jobs, atrm deletes jobs, identified by
their job number.

So I am looking to undestand, whether Android or the Linux kernel has
a default AT command parser which supports the Hayes AT Command set,
which can be accessed by a DTE connected to the Android device over a
serial link.

I think this is a typical case for phones and other may have come
across the same question or issue, but I have not found an answer
searching on the Android forums.


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adding more info to clarify my question
*******************************************************************

To clarify my question, I am not trying to issue AT commands from the
Android phone. Rather I am looking to issue AT commands from a PC to
an Android phone over a serial link such as RS232/USB/Bluetooth.

I am trying to understand if Android inherently supports AT commands
and has an AT parser ?

For e.g. to establish a PPP link (dial-up connection) from Windows to
a device that supports PPP, windows will first send some AT commands
and finally the ATD (dial) command. The device responds with a CONNECT
response, afterwhich it switches to online mode and a PPP link is
established and IP data cab be sent between the PC and the device.
Thus typically such devices (modems) by default are in AT mode. ATD is
just one such command. There are several other AT commands supported
by the device.

Now to develop a similar device using Android, I'd like to do that
without significantly altering the Linux kernel or Andorid
architecture and am looking to understand if a AT command parser which
recognizes the standard set of AT commands is inhenrently supported by
android.

To make my question clearer, consider the case where a PC for e.g.
connects to a device (phone) using the BT DUNS (dialup networking)
profile. The DUNS profile requires the phone to support i.e. parse and
recognize certain AT commands such as AT&C, &D, &F, +GCAP, +GMI, +GMM,
+GMR, ATA, D, E, H, L, M etc.

How does Android address this ? Does it have native support for
reconizing and responding to such AT commands ?

thanks in advance!

[Matthias Weiler]

On 02/24/2012 10:22 PM, Hetal wrote:
> I am trying to understand if Android inherently supports AT commands
> and has an AT parser ?

The best ressource for understanding low level communication on Android
devices might be a thread on XDA:
http://forum.xda-developers.com/showthread.php?t=1471241

I hope you can find your answers there.

gl & hf,
Matthias