Problem in interfacing with pic16f877a and gsm (SIM900A)

[pradeep]

1) putty testing to gsm module working fine

our image is shown below:

 

2) plz check this program if any mistake is there or not……

 

OUR PROGRAM:

 

#include<pic.h>

#include<string.h>

__CONFIG( HS & WDTDIS & BOREN & LVPDIS );

unsigned char str1[4]=”ATn”;

unsigned char str3[10]=”AT+CPIN?n”;

unsigned char str4[16]=”ATD7418211136;n”;

 

 

void delay(unsigned int y)//delay prg

{

while(y–);

}

void pra()

{

delay(5000);

delay(100);

delay(5000);

delay(100);

 

delay(5000);

delay(100);

}

 

int a,b,c,d,e,i;

void main()

{

 

TRISC=0X80;

TXSTA=0X26;

RCSTA=0X80;

SPBRG=25;

 

while(1)

{

TRISB=0X01;

PORTB=0X36;

 

delay(1000);

 

 

for (a=0;a<;a++)

{

if(TRMT==1)

{

TRMT=0;

TXREG=str1[a];

delay(1000);

}

}

delay(5000);

 

 

for (c=0;c<=9;c++)

{

if(TRMT==1)

{

TRMT=0;

TXREG=str3[c];

delay(1000);

}

}

delay(5000);

 

 

for (d=0;d<=15;d++)

{

if(TRMT==1)

{

TRMT=0;

TXREG=str4[d];

delay(1000);

}

}

delay(5000);

 

delay(5000);

 

delay(5000);

 

 

while (1);

 

}

}

 

 

3) our UART output viewed in putty software, shown below

 

 

4) our connection diagram:-

 

 

we have tried to change all sorts connection between tx and rx.. we have no any more futher ideas to proceed… plz help us out… check our program or other circiut mistakes if we have done…. plz correct and reply to our doubts… and if possible mail us the correct coding and connection diagram… mail id: [email protected]

plz help us we are beginners…

[Ganesh Selvaraj]

the problem is with your program.

unsigned char str1[4]=”ATn”;

unsigned char str3[10]=”AT+CPIN?n”;

unsigned char str4[16]=”ATD7418211136;n”;

 

You need to use ‘r’ and not ‘n’ . so change that part to

 

unsigned char str1[4]=”ATr”;

unsigned char str3[10]=”AT+CPIN?r”;

unsigned char str4[16]=”ATD7418211136r”;

 

[pradeep]

r does nt wrk.
Now it wrkd fine i used both n end of each liner nd n nd increased te delay
thanks

[Ganesh Selvaraj]

oh fine. And you are welcome. If you have any more queries do post them here.

[erwin]

[Shabuj]

I need a microc code for voice call by sim900A using push button. When i press button for 2 sec then i get a phone call in my hand set
Please help me

[Author]

Posts