Unable to read sms from GSM which is interfaced to 8051

[deep0177]

Hi want to read sms from GSM which is interfaced to 8051 micro controller , i am using Sim 900 A Gsm module whenever i tried to read the sms i am getting some garbage value as a response, both GSM and serial comm. baud rate are set at 9600 .


Any suggestions regarding this please.


Regards
Deepak

 

[avineshb006@gmail.com]

Hi Deep0177

First did you checked the AT command for reading sms from the terminal which is you are using in your system.

Try these following commands
AT+CSQ
AT+CREG?
AT+CPMS="SM"
> It will show the Sim memory messages
Like 0,20,0,20
Hear 0 indicates the no of messages stored in the sim card and 20 is for total no of messages which able to store on to the sim card.
AT+CREG=1
> It will display the message content...

Try this way, and tell what you are getting in your terminal...

 

[tpetar]

How you interface GSM modem to 8051 ? Did you use MAX232 ?

Post circuit.

 

[g_shyam1682]

hi,

First of all Send "AT\r" to check your hardware and communication. if your module reply with "\r\nOK\r\n" then your communication ok.
Now send "AT+CPMS?\r" command to verify that there is any SMS store in Module, if it gives you that there is some SMS store in module, you can read it using "AT+CMGR=1\r". where 1 is memory index in your module.

Regards,
Ghanshyam

 

[jayanth.devarayanadurga]

AT+CMGR=X, X can be 1 to the max messages stored in SIM.

 

[binu_ji]

Hey check out this tutorials for GSM modem interfacing with 8051 microcontroller
https://www.8051projects.info/resources/categories/gsm-modem.8/

 

[deep0177]

How you interface GSM modem to 8051 ? Did you use MAX232 ?

Post circuit.

No i dont use MAX 232 i had connected the Tx and Rx of 8051 MCU to the Rx and Tx of GSM modem , sending sms was worked in that way , but problem with reading sms



Regards
Deepak

 

[g_shyam1682]

Hi,

If you successfully send SMS, then it is very very easy task to read SMS,
First check there is any SMS pending in GSM module using "AT+CPMS?\r"
If yes, then read using "AT+CMGR=1\r".
Simple.....

Regards,

 

[deep0177]

Hi to all when i give command AT+CPMS? it gives reply as follows
+CPMS: "SM",40,40,"SM",40,40,"SM",40,40

 

[fouwad]

first try sending sms from ur modem while using it on hyperterminal, carefully note down all the instructions needed to send it, make exact copy of it in ur code , test ur microcontroller on hyperterminal too, both the codes should be same , then interface both the devices with each ohters

 

[errakeshpillai]

Hello everyone,
This is the same problem which I faced during my project and I could not rectify this mistake. I would like to know if any solution is found to this.

Normally the garbage character problem occurs when there is a mismatch in the baud rate settings.
But in the case of GSM, the sending works absolutely fine. Its only the reception part that is creating problem.

 

[g_shyam1682]

Hi to all when i give command AT+CPMS? it gives reply as follows
+CPMS: "SM",40,40,"SM",40,40,"SM",40,40

Hi Friend,

If your modem gives you above reply means your modem has 40 SMS store.

Now you can read all SMS one by one using "AT+CMGR=X\r" where X replace with SMS count like 1,2,3,....40.
and you get reply like below example,

Send : AT+CMGR=1\r

Received : \r\n+CMGR: "REC UNREAD","+919000700123",,"12/10/03,10:50:13+22"Here is your SMS message\r\n
Received : \r\nOK\r\n

Hope this is help you,

Regards,

 

[deep0177]

Hi anyone can please tell me how to read the sms from gsm using 8051??

 

[jayanth.devarayanadurga]

Connect your gsm modem or mobile to PC and issue at command AT+CMGF=1 and AT+CMGR=1. It will give some response. Take a screenshot of the Serial Terminal software showing the responses and post it. I will write a code.

https://www.edaboard.com/threads/290658/

Post your Serial interrupt routine.

---

Code C - [expand]
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2
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5
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void recieve() interrupt 4     Function to recieve data serialy from RS232 
{
        msgIN[i++]=SBUF;
        RI=0;                // Reset the serial interrupt after recieving the byte
        msgIN[i] = '\0';   
}

---

 

[jayanth.devarayanadurga]

@errakeshpillai

Can you post your code which displays garbage characters. Let me try to fix it.

 

[deep0177]

Thank you Jayanth.....I am posting my code

#include <REGX52.H>
//LCD Declaration//
#define LCD P1
sbit rs=P2^0;
sbit rw=P2^1;
sbit en=P2^2;

void delayms(unsigned char);
void delayus(unsigned char);
void lcd_init();
void lcd_reset();
void lcd_cmd (char);
void lcd_data(unsigned char);
void lcd_str (unsigned char *);
void clear(void);
void tx0(unsigned char);
void delay_sms (unsigned int);
void ms_delay(unsigned int itime);
void SMSString(char*text) ;
void init();
void read_text(unsigned char * , unsigned char * , unsigned char *);

unsigned char j,abc;
unsigned char idata msg1[150];
unsigned char rec_no[20];
unsigned char time_date[20];


void serial () interrupt 4
{
msg1[abc]=SBUF;
abc++;
RI=0;
}


void main (void)
{
/*
if u do not want to check "OK" response after each AT command then
enable interrupt IE=0X90 ; after last AT command of  
SMSString( "AT+CMGR=1\r"); // AT command to read sms
so after that u recieve a no of bytes from modile if u disable it then u do not reieve
it even data comes

use a virtual terminal in Proteus
run a Proteus and right click on virtual terminal and click on option echo character display.
in Proteus there is no mobile model so u should enter text in hyper terminal to suppose gsm Modem is responding.
use serial receive interrupt to receive data
check here

*/
clear();
init();
lcd_init();

SMSString("AT\r"); // AT commands to initialize gsm modem
delay_sms(1000);

SMSString( "ATe0\r"); // turn off echo
delay_sms(1000);

SMSString( "AT&W\r"); // save settings
delay_sms(1000);

SMSString( "AT+CMGF=1\r"); // select text mode for sms
delay_sms(1000);

SMSString( "AT+CNMI=2,1,0,0,0\r"); // notification of new sms
delay_sms(1000);

SMSString( "AT+CMGR=1\r"); // AT command to read sms

IE=0X90;   // Enable serial interrupt
delay_sms(5000);

/* i get a response like this

// +CMGR: "REC READ" ,"+2347060580383","10/10/23,14:29:33+04"
// device1 off
// Ok. */

// read sms and store in buffer msg1

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


void init(void)
{
j=0;
abc=0;
TL1=0XFD; //9600 @ 11.0592
TH1=0xFD;
TMOD=0x20;
SCON=0x50;
TR1=1;
}

void SMSString(unsigned char* text) //function to send SMS using GSM modem
{
while (*text)
{
tx0(*text++);
}
}


void tx0(unsigned char x) //send data to serial port 0
{
EA=0;
SBUF=x;
while(TI==0);
TI=0;
EA=1;
}


void delay_sms (unsigned int count)
{
unsigned int i;                         // Keil v7.5a
    while(count) {
        i = 115;
                while(i>0) i--;
        count--;
}
}

void read_text( unsigned char *msg,unsigned char *no ,unsigned char *time)
{
unsigned char *temp;
temp=msg;
do
msg++;
while(*msg!='+');        
do
msg++;
while(*msg!='+');         //  reaching at no
do
*no++=*msg++;
while(*msg!='"');         // reaching at time
*no++='\0';
msg++;
msg++;
msg++;
do
*time++=*msg++;
while(*msg!='+');         // raching at message
*time='\0';
do
msg++;
while(*msg!='\n');
msg++;
do
*temp++=*msg++;
while(*msg!='\r');       // reaching at end of message
*temp='\0';

lcd_cmd(0x80);            // ist line address
lcd_str(rec_no);          // array having receipt no
lcd_cmd(0xC0);            // 2nd line address
lcd_str(time_date);       // array having date and time
lcd_cmd(0x94);            // 3rd line address
lcd_str(msg1);            // array having message
}


void lcd_init()
	{
	
	lcd_cmd(0x38);
	lcd_cmd(0x0F);
	lcd_cmd(0x01);
	lcd_cmd(0x06);
	lcd_cmd(0x80);
	}
	
void lcd_cmd(unsigned char value)
{
  LCD=value;
  rs=0;
  rw=0;
  en=1;
  ms_delay(1);
  en=0;
 }
 void lcd_data(unsigned char value)
 { 
   LCD=value;
   rs=1;
   rw=0;
   en=1;
   ms_delay(1);
   en=0;
 }


 void ms_delay(unsigned int itime)
{
  unsigned int i,j;
  for(i=0;i<itime;i++){
		
  for(j=0;j<1200;j++);
	}
}
void clear(void)
{
unsigned char a;
for(a=0;a<100;a++)
msg1[a]=0x00;
}

void lcd_str (unsigned char *str)
{
        while(*str){
                lcd_data(*str++);
        }
}

[COLOR="silver"][SIZE=1]- - - Updated - - -[/SIZE][/COLOR]

i am also working on this code  but also getting garbage value 

#include <reg52.h>     
#include <stdio.h>
                        
//Delay Functions Declarations	********************************
void ms_delay(unsigned int itime)
{
  unsigned int i,j;
  for(i=0;i<itime;i++){
		
  for(j=0;j<1200;j++);
	}
}	
void delay()
{
	int i,j;
	for(i=0;i<1000;i++)
  for(j=0;j<5000;j++);
}
// Delay functions declaration********************************									

			
//LCD Function Declarations------------------------
sbit rs=P2^0;
sbit rw=P2^1;
sbit en=P2^2;
#define LCD P1
void lcd_cmd(unsigned char value)
{
  LCD=value;
  rs=0;
  rw=0;
  en=1;
  ms_delay(1);
  en=0;
 }
void lcd_data(unsigned char value)
 { 
   LCD=value;
   rs=1;
   rw=0;
   en=1;
   ms_delay(1);
   en=0;
 }
void string_lcd (unsigned char* ptr)
 { 
   unsigned int h,j=0;
   while(*ptr)
   {
      h++;
	  if(h<15)
	  {
	    lcd_data(*ptr++);
	  }
	  if(h>=15)
	  {
	    lcd_cmd(0xc0+j);
		lcd_data(*ptr++);
		j++;
	  }
	  // *(ptr++);
	  }
	}
	
void lcd_init()
	{
	
	lcd_cmd(0x38);
	lcd_cmd(0x0F);
	lcd_cmd(0x01);
	lcd_cmd(0x06);
	lcd_cmd(0x80);
	}
// LCD Functiond End----------------------------
//Gsm Functions	
void String_Gsm(unsigned char*);	
void Write_Gsm(unsigned char);	
void Read_Gsm(unsigned int);
	
//	
	
unsigned char mysms;     
unsigned char buffer[20];	
void main (void) 
{       
	unsigned char at[]="at";
	unsigned int i=0;	
	TMOD = 0x20;    
	SCON = 0x50;    
	TH1  = -3;    
	TR1  = 1;
	TI=1;
	lcd_init();
	string_lcd("Testing GSM");
	lcd_cmd(0xc0);
	string_lcd("Reading SMS");
	ms_delay(500);
	lcd_cmd(0x01);
	lcd_cmd(0x06);
	lcd_cmd(0x80);
	
                 String_Gsm("at");
	ms_delay(2);
	Write_Gsm(0x0d);
	ms_delay(1);
	read_Gsm(2);
	ms_delay(50);
	lcd_cmd(0x01);
	String_Gsm("at+cmgf=1");
	ms_delay(10);
	Write_Gsm(0x0d);
	ms_delay(1);
	read_Gsm(2);
	ms_delay(50);
	lcd_cmd(0x01);
	
               String_Gsm("at+cnmi=2,1,0,1,0");
	ms_delay(10);
	Write_Gsm(0x0d);
	ms_delay(1);
	read_Gsm(2);
	ms_delay(50);
	lcd_cmd(0x01);
	String_Gsm("at+cmgr=1");
	ms_delay(2);
	Write_Gsm(0x0d);
	ms_delay(1);
	read_Gsm(20);
	
}

void String_Gsm(unsigned char *s)
{
		while(*s)
		Write_Gsm(*s++);
}

void Write_Gsm(unsigned char c)
{
	SBUF=c;
	lcd_data(c);
	while(TI==0);
	TI=0;
	ms_delay(2);
}

void read_Gsm(unsigned int count)
{
	int i=0;
	while(count>0)
	{		
		while(RI==0);
		while(RI==0);
		while(RI==0);
		if(RI==1)
		{
				i=0;
				buffer[i]=SBUF;
				lcd_data(buffer[i]);
				RI=0;
			i++;
		}
		if(count==0)break;
		count --;
	}	
}
void serial_intr(void) interrupt 4    //interrupt service routine for serial interrupt
{
if(TI==1) 			//if transmit interrupt, clear TI
		{
		 TI=0;
		} 
	if(RI==1) 			//if receive interrupt
	{
			mysms=SBUF;
			lcd_data(mysms);
			RI=0;
	}  
}

 

[deep0177]

Hi when i connected the GSM module serially to PC on hyper terminal it shows as following ....sorry am unable to take screenshot ...

AT+CMGR=4

+CMGR: "REC READ","TD-610401","","12/08/24,10:52:41+22"

420 Mins for 15days!! 300 ALL Mins+120 LOCAL T2T mins as bonus on RC120.Hurry! o
ffer valid only on 24th,25th & 26thAug12.Extra benefits will credited in 72hours

OK

 

[jayanth.devarayanadurga]

420 Mins for 15days!! 300 ALL Mins+120 LOCAL T2T mins as bonus on RC120.Hurry! o
ffer valid only on 24th,25th & 26thAug12.Extra benefits will credited in 72hours

is the actual message.

 

[deep0177]

Hi jayanth ..yes thats the actual message

 

[jayanth.devarayanadurga]

Issue command AT+CMGR=1, AT+CMGR=2, AT+CMGR=5 and take a screenshot of the response by pressing PrintScreen button on keyboard and then pasting the image from clipboard to Paint. Post the Screenshot.