Categories: GSM | Symbian C++ | Code Examples | How To

This page was last modified 19:52, 23 May 2008.

From Forum Nokia Wiki

#include <c32comm.h> 
Link Against : c32.lib

TRequestStatus status;
RCommServ commServer;
User::LeaveIfError(commServer.Connect());
 
_LIT(KCsyName, "dataport");
User::LeaveIfError(commServer.LoadCommModule(KCsyName));
 
_LIT(KDataPort, "DATAPORT::0");
 
RComm comm;
User::LeaveIfError(comm.Open(commServer1, port, ECommShared));
 
//Send AT Commands to MODEM.
 
_LIT8(cmd,"AT\r\n");
comm.Write(status, cmd);
User::WaitForRequest(status);
User::After(5000000);
comm.Close();
commServer.Close();

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.

#include <c32comm.h>       //Link Against : c32.lib
 
_LIT(KCsyName,"DATAPORT");
_LIT(KDataPort,"DATAPORT::1");
RCommServ commServer;
RComm comm;
 
// Connect the server
User::LeaveIfError(commServer.Connect());
 
// Load the CSY module
User::LeaveIfError(commServer.LoadCommModule(KCsyName());
 
// Open the port
User::LeaveIfError(comm.Open (commServer, KDataPort, ECommShared));
 
// Write any AT command
_LIT8(KWriteCommand, "AT+CGSN\r\n");
TRequestStatus writeStatus;
comm.Write(writeStatus, KWriteCommand());
User::WaitForRequest(writeStatus);
 
// Put some delay before reading the response
User::After(KTimeDelay);
 
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;
while( count < 2 )
       {
	des.Zero();
	aCommPort.ReadOneOrMore(readStatus, des);
	User::WaitForRequest(readStatus);
	User::LeaveIfError(readStatus.Int());
	count++;
	User::After(500000);
	}
 
// Close the port and the server
comm.Close();
commServer.Close();

Note

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.

Related Links

• AT Commands
• Image:Send AT Commands.zip