Interfacing SIM300

May 6, 2013 Coded in C for the Microchip PIC16

Driver for interfacing sim300 to send and read sms

#use rs232(baud=19200,xmit=pin_C6,rcv=pin_C7,parity=n,bits=8,stop=1,stream=GSM,timeout=100)
 
int8 sms_buffer[40],ph_number[15]; 
 

 
void sync()
 {
	fprintf(GSM,"AT\n\r");
	delay_ms(100);
	fprintf(GSM,"AT\n\r");
	delay_ms(100);
	fprintf(GSM,"AT\n\r");
	delay_ms(100);
	fprintf(GSM,"AT\n\r");
	delay_ms(100);
}

void dial_modem()
{
	int8 i=0;
	fputc('A',GSM);
	fputc('T',GSM);
	fputc('D',GSM);
	fputc(' ',GSM);
	
	while(ph_number[i] !='\0' && i<16)
	{
		fputc(ph_number[i],GSM);
		i++;
	}
	fputc(';',GSM);
	fputc(0x0D,GSM);
	fputc(0x0A,GSM);
} 

void hang_call()
{
	fputc('A',GSM);
	fputc('T',GSM);
	fputc('H',GSM);
	fputc(0x0D,GSM);
	fputc(0x0A,GSM);
}
void set_text_mode()
{
	sync();
	fprintf(GSM,"AT+CMGF=1\n\r");
	
}
int1 get_sms(int8 intex_no)
{
	int8 count=0;
	set_text_mode();
	delay_ms(100);
	fprintf(GSM,"AT+CMGR=%u\n\r",intex_no);
	while(fgetc(GSM)!=0x0A);
	if(fgetc(GSM)=='+')
	{	
		
		while(fgetc(GSM)!='"');
		while(fgetc(GSM)!='"');
		while(fgetc(GSM)!='"');
		do
		{
			ph_number[count]=fgetc(GSM);
			count++;
		}while(ph_number[count-1] !='"' && count<15);
		ph_number[count-1]='\0';
		while(fgetc(GSM)!=0x0A);
		count=0;
		do
		{
			sms_buffer[count]=fgetc(GSM);
			count++;
		}while(sms_buffer[count-1] !=0x0D && count<24);
		sms_buffer[count-1]='\0';
		delay_ms(500);
		sync();	
		fprintf(GSM,"AT+CMGD=%u\n\r",intex_no);//delete sms
		
	}
	else
	{
		count=24;
	}	
	if(count>=24)
		return 0;
	else
	{
		return 1;	
	}	
		
}
void send_sms()
{
	int8 array_index;
	set_text_mode();
	delay_ms(100);
	fprintf(GSM,"AT+CMGS=");
	fputc('"',GSM);
	array_index=0;
	while(ph_number[array_index] !='\0')
	{
		fputc(ph_number[array_index],GSM);
		array_index++;
	}
	fputc('"',GSM);
	fputc(0x0D,GSM);
	fputc(0x0A,GSM);
	while(fgetc(GSM) !=' ');
	array_index=0;
	while(sms_buffer[array_index] !='\0')
	{
		fputc(sms_buffer[array_index],GSM);
		array_index++;
	}
	fputc(0x1A,GSM);// Ctrl-Z
	delay_ms(100);
}		

int8 read_strength()
{
	int8 rssi[3],rssi_byte;
	//output_low(PIN_A5);
	fprintf(GSM,"AT+CSQ\n\r");
	while(fgetc(GSM) !=' ');
	//output_high(PIN_A5);
	rssi[0]=fgetc(GSM) & 0x0F;
	rssi[1]=fgetc(GSM) & 0x0F;
	rssi_byte=rssi[0]*10;
	rssi_byte=rssi_byte+rssi[1];
	return rssi_byte;
}

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