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How to send AT Commands

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Article Metadata
Code ExampleCompatibility
Platform(s): S60 3rd Edition, S60 5th Edition.
Platform Security
Signing Required: DevCert
Capabilities: NetworkControl, CommDD
Created: User:Kanu123 (29 Jun 2007)
Last edited: morkki (28 May 2012)
#include <c32comm.h> 
Link Against : c32.lib

TRequestStatus status;
RCommServ commServer;
_LIT(KCsyName, "dataport");
_LIT(KDataPort, "DATAPORT::0");
RComm comm;
User::LeaveIfError(comm.Open(commServer1, port, ECommShared));
//Send AT Commands to MODEM.
comm.Write(status, cmd);

How to Write and Read AT Commands

To pass AT commands to the GSM modem of the mobile device, we need to use the Dataport CSY module and read/write commands on Port 1 of this module.

This port is not available on the emulator so this code will work only on a mobile device.

This code is well tested on Nokia 6600, Nokia 6670 and Nokia 3230.

Header needed:

#include <c32comm.h>

Library needed:

LIBRARY  c32.lib

Capabilities needed:

Capability NetworkControl CommDD
RCommServ commServer;
RComm comm;
// Connect the server
// Load the CSY module
TInt err = commServer.LoadCommModule(KCsyName);
if ( err )
//add here needed logging etc.
User::Leave( err );
// Open the port
err = comm.Open (commServer, KDataPort, ECommShared);
if ( err )
//add here needed logging etc.
User::Leave( err );
// Write any AT command
_LIT8(KWriteCommand, "AT+CGSN\r\n");
TRequestStatus writeStatus;
comm.Write(writeStatus, KWriteCommand());
// Put some delay before reading the response
const TInt KTimeDelay = 1000000;
// Here I am reading the port twice since the first read will be an echo
// i.e the same command will be received in response
// Second read will give the actual response, in this case, the IMEI number of
// the device
// Putting in a while loop hangs the application since there is nothing to read
// on the third read, and so the port keeps on waiting for a response
TBuf8<1024> des; // Response will be received in this buffer.
// 1024 is the default buffer size of the receive buffer
TInt count = 0;
TRequestStatus readStatus;
while( count < 2 )
comm.ReadOneOrMore(readStatus, des);
// Close the port and the server


Logic for reading of AT commands can be implemented in a much better manner according to the requirement. Here I have used a makeshift method of counter just to demonstrate the type and number of responses received.

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This page was last modified on 28 May 2012, at 11:28.
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