GSM MODEM with 8051

Hi Ajay,

I want to do in 1st method. i.e through interrupt for notification of new msg arrival.
Can u suggest which interrupt vll be more useful( i have used serial int already in program).

hi kirangowle
in serial communication serial interrupt is use ful
enable serial interrupts and wait for notification of new message
if u received the notification of new sms then send command to modem to read sms otherwise do again the previous job

Hi mojaka and ajay,

//main()
SMSString("AT\r"); // AT commands to initialize gsm modem
delay(50);

SMSString( "ATe0\r"); // turn off echo
delay(50);

SMSString( "AT&W\r"); // save settings
delay(50);

SMSString( "AT+CMGF=1\r"); // select text mode for sms
delay(50);
SMSString( "AT+CNMI=2,1,0,0,0\r"); // notification of new sms
delay(40);

//New msg indication.
// +CMTI: "SM",3

IE=0X90;   // Enable serial interrupt
delay(10);
*index=read_notification(msg1);
clear();
IE=0x00;

SMSString( "AT+CMGR="); // AT command to read sms
SMSString(index);
SMSString('\r');

IE=0X90;   // Enable serial interrupt
delay(80);


// read sms and store in buffer msg1


read_text(msg1,rec_no,time_date);
clear();
IE=0X00;     // Disable all interrupt
while(1);

char read_notification(unsigned char *msg)
{
unsigned char array[15],i,index_no;
i=0;
do
msg++;
while(*msg!='+'); // to check for first '+'.
do
{
array[i]=*msg++;
i++; 
}while(*msg!='\n');	 // Check for new line.
i--;
if(array[0]=='C' && array[1]== 'M' && array[2]=='T' && array[3]== 'I')
{
      index_no=array[i];
     return index_no;
}

In LCD garbage values are being displayed.
I m bit confused how to check a new msg.becoz wen i reset the controller. controller again sents all AT commands at this time modem notification had been gne without knowing to controller.

hi kirangowle
do little modify ur code
let say here u want that when new message notification received u display on lcd that new message receive
for that try this

/main()
SMSString("AT\r"); // AT commands to initialize gsm modem
delay(50);

SMSString( "ATe0\r"); // turn off echo
delay(50);

SMSString( "AT&W\r"); // save settings
delay(50);

SMSString( "AT+CMGF=1\r"); // select text mode for sms
delay(50);
SMSString( "AT+CNMI=2,1,0,0,0\r"); // notification of new sms
IE=0X90;   // Enable serial interrupt
delay(80);


unsigned read_notification(unsigned char *msg)
{
unsigned char array[15],i,index_no;
i=0;
do
msg++;
while(*msg!='+'); // to check for first '+'.
do
{
array[i]=*msg++;
i++;
}while(*msg!='\n');      // Check for new line.
i--;
if(array[0]=='C' && array[1]== 'M' && array[2]=='T' && array[3]== 'I'  && array[4]== ':'  && array[5]== ' '  && array[6]== '"'  && array[7]== 'S'  && array[8]== 'M'  && array[9]== '"  && array[10]== ','  && array[11]== '3'')
{
// display on lcd that new message indication
}

u can use string comparison using built in library or store a +CMTI: "SM",3
in rom of 8051 and compare it with array values instead of long if else statements
do this the go to nrxt to decode the message

Hi mojaka,

Whether i m comparing correctly with \n r it should be '\r'..

unsigned read_notification(unsigned char *msg)
{
unsigned char array[15],i;
i=0;
do
msg++;
while(*msg!='+'); // to check for first '+'.
do
{
array[i]=*msg++;
i++;
}while(*msg!='\n');      // Check for new line.
i--;
if(array[0]=='C' && array[1]== 'M' && array[2]=='T' && array[3]== 'I'  && array[4]== ':'  && array[5]== ' '  && array[6]== '"'  && array[7]== 'S'  && array[8]== 'M'  && array[9]== "'"  && array[10]== ','  && array[11]== '3' && array[12]== '\n')
{
lcdcmd(0xc0);
lcdstr("New Msg");
delay(100);
}
return 0;
}

In +CMTI: "SM",3(\r or \n is there).
I m getting junk values on LCD from above program.

in the above code lcd should display a new message otherwise not any thing do a step by step
first just receive a notification from modem compare it and display it is ok etc to confirm this step
then goto next one

Hi Mojaka,

Its working !! I have given displays at each loop just to check whether it enter it or not.

LCD displays "New MSG"

unsigned read_notification(unsigned char *msg)
{
unsigned char array[15],i;
i=0;
do
{
msg++;
i++;
lcdcmd(0x80);
lcdstr("InLoop1");
delay(40);
}while(*msg!='+' && i!=15); // If + doesnt aries then it ll hanged so i used a counter(i)..
i=0;

do
{
array[i]=*msg++;
lcdcmd(0x80);
lcdstr("InLoop2");
delay(40);
i++;
}while(*msg!='\n' && i!=15);      // Check for new line.

i--;
lcdcmd(0x80);
lcdstr("OutLoop2");
delay(40);

if(array[0]=='+' && array[1]=='C' && array[2]== 'M' && array[3]=='T' && array[4]== 'I'  && array[5]== ':'  && array[6]== ' '  && array[7]== '"'  && array[8]== 'S'  && array[9]== 'M'  && array[10]== '"'  && array[11]== ',' && array[12]== '3' /*&& array[13]== '\n'*/)
{
lcdcmd(0x80);
lcdstr(" New MSG ");
delay(200);
}

lcdcmd(0x80);
lcdstr("OutLoop3");
delay(40);
return 0;
}

void main(){
clear();
lcdinit();
lcdcmd(0x80);
lcddata('K');
delay(10);
init();

SMSString("AT\r"); // AT commands to initialize gsm modem
delay(50);

SMSString( "ATe0\r"); // turn off echo
delay(50);

SMSString( "AT&W\r"); // save settings
delay(50);

SMSString( "AT+CMGF=1\r"); // select text mode for sms
delay(50);
SMSString( "AT+CNMI=2,1,0,0,0\r"); // notification of new sms
delay(40);
while(1)
{
IE=0X90;   // Enable serial interrupt
delay(10);
read_notification(msg1);
}
}

Now how to read that index no and send it to modem.
As per abv function index no will be in array[12] loc.
Now how to send this no. after the instruction AT+CMGR=?

you can replace this

if(array[0]=='+' && array[1]=='C' && array[2]== 'M' && array[3]=='T' && array[4]== 'I'  && array[5]== ':'  && array[6]== ' '  && array[7]== '"'  && array[8]== 'S'  && array[9]== 'M'  && array[10]== '"'  && array[11]== ',' && array[12]== '3' /*&& array[13]== '\n'*/)

with a better loop, coz its not compulsory that you always get 3 in new sms indication. so check it like this..

if(strncmp(array, "+CMTI", 5) == 0){
    //Yes its a new message ..
    //Now lets read the index
    //we first have to truncate the array... to use string functions
    array[14] = '\0'; //coz array[12] and array[13] may contain your index
    index = atoi(&array[12]);
    //now index is having 3 or 10 or whatever index comes with notification.
}

Hi

index = atoi(&array[12]);

atoi is an built in function?
While compling error missing prototype.
I have added header file string.h & absacc.h

hi
it is an built in fuction of STDLIB.h
it Converts string to integer
syntax is as
int atoi ( const char * str );