To interface GSM SIM900 with 8051

[prajwal]

hello, Im a newbee to this site. But im really happy for being a member now. i learnt lots of things after coming here. the tutorial section is simply best!!! i saw the GSM interface with 8051 tutorial. but now i want to send and recieve sms using the modem. can anybody help me out??? pls im a beginner in programming n have interest in doing projects but i dint had proper source. pls do respond to my kind request. Thanks in advance….

[Amrith]

Hi Prajwal,

Good !!!

We are here to help you. Please start the project & post your difficulties.

[Anonymous]

Thank u so much for responding to my request. Sir i hav a GSM modem named “WISMO” can this be used for interfacing or should i buy a new one??? pls suggest.. This modem has no changes compared to other. Same AT commands…

 

[Amrith]

Hi,

You can start using the modem you got. AT commands are independent of any GSM modem. 

All the best & post your doubts & difficulties

[prajwal]

Thank u sir. I am starting with the project from tomorrow… I have developed the code for sending the message. If it dont work out il post it… on the other way even if it works out i will post it

[Amrith]

Good prajwal..

Appreciate your effforts. if you find any difficulties post your doubts.

All the best !!!!

[gouday]

i am doing project on gsm modem to send sms.i ve connected sim 900 modem through 8051 with max232.i ve the code as follows…………………………which was there in this website only,i ve just editted and added.i ve given the o/p to lcd.i am not getting a correct response……………please help me out……….

 

 

#include<reg51.h>

#define port P1

#define dataport P2 // Data port for LCD

sbit rs = port^0;

sbit rw = port^1;

sbit en = port^2;

int count,i;

unsigned char check,str[50];

bit check_space;

 

void init_serial() // Initialize serial port

{

TMOD=0x20; // Mode2

TH1=0xfd; // 9600 baud

SCON=0x50; // Serial mode=1 ,8-Bit data,1 Stop bit ,1 Start bit, Receiving on

TR1=1; // Start timer

}

void delay(unsigned int msec) // Function for delay

{

int i,j;

for(i=0;i<msec;i++)

   for(j=0; j<1275; j++);

}

 

void lcd_cmd(unsigned char item) // Function to send command on LCD

{

dataport = item;

rs= 0;

rw=0;

en=1;

delay(1);

en=0;

return;

} 

 

void lcd_data(unsigned char item) // Function to display character on LCD

{

dataport = item;

rs= 1;

rw=0;

en=1;

delay(1);

en=0;

return;

}

 

void lcd_data_string(unsigned char *str) // Function to display string on LCD

{

int i=0;

while(str!=’’)

{

   lcd_data(str);

   i++;

   delay(10);  

    }

return; 

}

void lcd()

{

lcd_cmd(0x38);   // For using 8-bit 2 row LCD 

delay(5);  

lcd_cmd(0x0F);         // For display on cursor blinking

delay(5);

lcd_cmd(0x80);   // Set the cursor on first position of LCD 

delay(5);  

}

 

void transmit_data(unsigned char str) // Function to transmit data through serial port

{

SBUF=str;   //Store data in SBUF

while(TI==0); //Wait till data transmits

TI=0;

}

 

 void receive_data()  interrupt 4 // Function to recieve data serialy from RS232 into microcontroller

 {

RI=0;

str[++count]=SBUF; //Read SBUF

 

 }

  

unsigned char byte_check() // Function to check carraige return and new line character

{

switch(str[0])

{

case 0x0a:

{ // Return 0x00 for new line

return 0x00;

break ;

}

case 0x0d:

{ // Return 0x01 for carriage return

return 0x01;

break ;

}

default :return 0x02 ; // Return 0x02 for characters except new line and carriage return

}

}

 

void main()

{ 

lcd(); // Initialize LCD

init_serial(); // Initialize serial port

count=(-1);

delay(500);

lcd_data_string(“Ready”);

delay(10);

lcd_cmd(0x01);

 

IE=0x90;

transmit_data(‘a’);  

delay(1);

transmit_data(‘t’);

delay(1);

transmit_data(0x0d);   // Transmit carriage return to serial port

delay(500); 

transmit_data(‘a’);  

delay(1);

transmit_data(‘t’);

delay(1);

transmit_data(‘+’);  

delay(1);

transmit_data(‘c’);

delay(1);

transmit_data(‘m’);  

delay(1);

transmit_data(‘g’);  

delay(1);

transmit_data(‘f’);  

delay(1);

transmit_data(‘=’);

delay(1);

transmit_data(‘1’);

delay(1);

transmit_data(0x0d);   // Transmit carriage return to serial port

delay(500);

 

transmit_data(‘a’);  

delay(1);

transmit_data(‘t’);

delay(1);

transmit_data(‘+’);  

delay(1);

transmit_data(‘c’);

delay(1);

transmit_data(‘m’);  

delay(1);

transmit_data(‘g’);

delay(1);

transmit_data(‘s’);  

delay(1);

transmit_data(‘=’);

delay(1);

transmit_data(‘ ” ‘); //    added mobile  number here

delay(1);

transmit_data( );  

delay(1);

transmit_data( );           

delay(1);

transmit_data( );  

delay(1);

transmit_data( );

delay(1);

transmit_data( );  

delay(1);

transmit_data( );

delay(1);

  transmit_data( );  

delay(1);

transmit_data( );

delay(1);

transmit_data( );  

delay(1);

transmit_data( );

delay(1);

transmit_data(‘ ” ‘);

delay(1);

transmit_data(0x0d);   // Transmit carriage return to serial port

delay(500);

transmit_data(‘h’);

delay(1);

transmit_data(‘e’);  

delay(1);

transmit_data(‘l’);

delay(1);

transmit_data(‘l’);

delay(1);

transmit_data(0x1a);

delay(500);

 

 

while(1)

{

   lcd_cmd(0x80);

if(count>=0)

{

check=byte_check(); // Check the character

if(check!=0x00)

{

if(check==0x01)

{

if(check_space==1) // Check previous character

{

lcd_data(0x20);

check_space=0;

delay(1000);

}

}

else

{

lcd_data(str[0]);

delay(1000);

check_space=1;

}

}

count–;   

for(i=0;i<count;i++)   // Shift the whole array to one left

{

str=str[i+1];

}

}

}

}

 

 

[Omer Fayyaz]

hye…. bro there is no need to use max232 because both 8051 and SIM900 have TTL/Cmos level… 

best of luck

 

[nidhin.k]

hai PRAJWAL………………

 

 

 

for sending and receiving sms you must initialaze ur gsm modem.

 

initialization commands are (steps)

 

AT                               /*you will get a reply “OK ” ,if the modem is working*/

AT+CMGF=1             /* convert to text mode  */

AT+CNMI=2,2,0,0,0    /*receive msg , after reading it will automatically deleted  */

 

 

for sending

 

AT+CMGS=”mobile number”<press enter key>

<type msg>

<press control key+Z>

 

 

for calling….

 

 

ATD<mobile number>; <press enter key>

 

 

 

 

 

[rathang]

Can someone say  how to interfacing sim900 to 89v51rd2? kell coading only AT will be display and ok will be showing 

 

 

 

[ligeesh]

sir,

my project is gsm based electronics notice board.here we are using gsm modem sim 900a model.i want the program for this project.pls help me.

[monica]

Hii!!! Can anyone post the code for sending data through gsm (sim 900) with 8051 microcontroller and lcd using AT commands ?? plz..

[umesh mehtre]

can i get gsm(sim900) program..

 

[umesh mehtre]

plzz help…

[Author]

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