8051 – GSM Interfacing

Hi Guys today we will see GSM interfacing with 8051. Before that please take a look at GSM Module Introduction.  And you should know the Serial Communication of 8051. I’ve posted that also. Please go through that (Serial Communication).

GSM interfacing with 8051

Components Required

  • GSM SIM900A module
  • 8051 Development Board

Connection

GSM interfacing with 8051

Micro controller’s RX (P3.0) is connected into GSM module’s TX and Micro controller’s RX is Connected into GSM module’s RX pin.

Code

SMS Sending Code

This code is used to send the message to the particular number. You can also download this code from Github.

#include <reg51.h>

#define NUMBER 0123456789         //Here insert your number where you want to send message

void ser_init();
void tx(unsigned char send);
void tx_str(unsigned char *s);
unsigned char rx();

void sms(unsigned char *num1,unsigned char *msg);
void gsm_delay();

unsigned int dell;

int main()
{
        ser_init();
        
        sms(NUMBER, "Welcome to the Embetronicx");
        while(1);
}

void ser_init()
{
	SCON=0x50;
	TMOD=0x21;
	TH1=0xFD;
	TL1=0xFD;
	TR1=1;
}

void tx(unsigned char send)
{
	SBUF=send;
	while(TI==0);
	TI=0;
}

void tx_str(unsigned char *s)
{
	while(*s)
		tx(*s++);
}

unsigned char rx()
{
	while(RI==0);
	RI=0;
	return SBUF;
}

void gsm_delay()
{
	unsigned int gsm_del;
	for(gsm_del=0;gsm_del<=50000;gsm_del++);
}

void sms(unsigned char *num1,unsigned char *msg)
{
	tx_str("AT");
	tx(0x0d);
	gsm_delay();

	tx_str("AT+CMGF=1");
	tx(0x0d);
	gsm_delay();

	tx_str("AT+CMGS=");
	tx('"');
	while(*num1)
		tx(*num1++);
	tx('"');
	tx(0x0d);
	gsm_delay();

	while(*msg)
		tx(*msg++);
	tx(0x1a);
	gsm_delay();
}

Calling Code

This code is used to Call to the particular number. You can also download this code from Github.

#include <reg51.h>

#define NUMBER 0123456789         //Here insert your number where you want to call

void ser_init();
void tx(unsigned char send);
void tx_str(unsigned char *s);
unsigned char rx();

void sms(unsigned char *num1,unsigned char *msg);
void gsm_delay();

unsigned int dell;

int main()
{
        ser_init();
        
        call(NUMBER);
        while(1);
}

void ser_init()
{
	SCON=0x50;
	TMOD=0x21;
	TH1=0xFD;
	TL1=0xFD;
	TR1=1;
}

void tx(unsigned char send)
{
	SBUF=send;
	while(TI==0);
	TI=0;
}

void tx_str(unsigned char *s)
{
	while(*s)
		tx(*s++);
}

unsigned char rx()
{
	while(RI==0);
	RI=0;
	return SBUF;
}

void gsm_delay()
{
	unsigned int gsm_del;
	for(gsm_del=0;gsm_del<=50000;gsm_del++);
}

void call(unsigned char *num2)
{
	tx_str("AT");
	tx(0x0d);
	gsm_delay();

	tx_str("AT+CMGF=1");
	tx(0x0d);
	gsm_delay();

	tx_str("ATD");
	while(*num2)
		tx(*num2++);
	tx(';');
	tx(0x0d);
	for(dell=0;dell<=30;dell++)
		gsm_delay();

	tx_str("ATH");
	tx(0x0d);
	gsm_delay();
}

If you have any doubt please comment below.

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