GSM interfacing with Atmega16

[Subhamoy Mahajan]

Right now I am trying a simple code of calling by GSM sim900 using atmega16
MY SETUP:Rx and Tx pins of atmega board are connected to Tx and Rx of my GSM modem and also to my uart bridge which i connect to my PC(done by splitting the Rx and Tx pins)-This was done so i could know whether my AT commands were given to modem or not
 

OBSERVATION;

AT commands appeared as i wanted in terminal(X-CTU I have Used) that means they were actually given to modem also(since i splitte the wires).But no call was made.However when i myself entered the AT commands During the same process I was succesful
 

MY code:

#define F_CPU 12000000UL

#include <util/delay.h>

#include <avr/interrupt.h>

#define BAUD 38400                                //setting up baud rate

#define bd (int)(F_CPU/16/BAUD-1)          //value of UDRR to be set

#include <avr/io.h>

void command(char*a)                   //function to send a string using pointers

{

int i;

for(i=0;a!='';i++)

{

while(!(UCSRA&(1<<UDRE)));

UDR=a;

_delay_ms(100);

}

 

}

flush ISR (USART_RXC_vect)        //flushing any type of echoes obtained

{

char recdata;

recdata=UDR;

}

int main(void)

{

sei();

UBRRH=(bd>>;

UBRRL=bd;

UCSRB|=1<<RXEN|1<<TXEN|1<<RXCIE;

UCSRC|=1<<URSEL|1<<UCSZ0|1<<UCSZ1;

 

 

_delay_ms(2000);

command("ATr");

_delay_ms(2000);

command("ATr");

_delay_ms(2000);

command("ATD+919933988118;r");

_delay_ms(20000);

command("ATHr");

 

    

 

while(1)

    {

 

        //TODO:: Please write your application code 

    }

}

 

 

Can any one please help me why my atmega is unable to do so or is there any problem in my code?

 

[Arjun Singh]

Hi Subhamoy

As i checked your code, i found some errors in it.

1. write UBRRL=bd; before UBRRH=(bd>>; as other wise you will discard lower byte.

2. Write command("ATrn"); instead of command("ATr"); (Enter is required also). 

3.

command("ATD+919933988118;r");

_delay_ms(20000);

 

you cant give more than 6000 ms of delay from your on delay command.

So rewrite 6000 here, for more delay you can write _delay_ms(6000); as many times as you required.

 

Do these modifications,  and tell me the results.

 

[Author]

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