Problem on GSM commucnication in PIC

[Mani Yuvan]

i try to sent the simple message through gsm modem but nothing to happen .please check the code and give any suggestion please.Im using sim300 module and c18 compiler

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#include<p18f452.h>
 
#include"H:\RECovery RObot\header files\delay.h"
 
#pragma config OSC=HS, OSCS=OFF #
 
pragma config DEBUG=OFF, LVP=OFF, STVR=OFF
 
#pragma config WDT=OFF
 
#pragma config BOR=OFF, PWRT=ON
 
void gsm_cmd(unsigned char);
 
void tx_data(unsigned char);
 
void gsm_ready(void);
 
unsigned char enter=0X0D;
 
unsigned char end=0X1A; unsigned char b[]={"haiii.."},i;
 
unsigned char format[]={"AT+CMGF=1"};
 
unsigned char num[]={"AT+CMGS=\"952xxxxxxx\""};
 
void tx_data(unsigned char c) {
 
while(PIR1bits.TXIF==0);
 
TXREG=c; PIR1bits.TXIF=0; }
 
void gsm_ready() { for(i=0;i<9;i++)
 
{
 
gsm_cmd(format[i]);
 
delay(1);
 
} tx_data(enter);
 
delay(1000);
 
for(i=0;i<20;i++)
 
{ gsm_cmd(num[i]);
 
delay(1); } tx_data(enter);
 
delay(1000); }
 
void gsm_cmd(unsigned char c)
 
{ if(c!=0x5C) // Not to send '\' cahracter
 
{ 
while(PIR1bits.TXIF==0); TXREG=c; PIR1bits.TXIF=0; }
 
}
 
void main() {
 
TXSTA=0X20;
 
SPBRG=64;//4800 bps for 20 Mhz crystal
 
TXSTAbits.TXEN=1;
 
RCSTAbits.SPEN=1;
 
gsm_ready(); delay(2);
 
for(i=0;i<7;i++) {
 gsm_cmd(b[i]); 
delay(1);
 
}
 
tx_data(enter);
 
tx_data(0X1A);
 
delay(1000);
 
}

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[ud23]

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Code C - [expand]
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SPBRG=64;//4800 bps for 20 Mhz crystal

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check your gsm is running with same baud rate. try with 9600 baud rate.Test your gsm with hyper terminal first.

 

[Mani Yuvan]

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Code C - [expand]
1
SPBRG=64;//4800 bps for 20 Mhz crystal

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check your gsm is running with same baud rate. try with 9600 baud rate.Test your gsm with hyper terminal first.

I also try this also.but nothing to happen.Im newer to Embedded systems.And i think i m not sure the delay part.please send me the working code for c18 compiler send sms from pic18f452 controller to one number.Thanks

 

[ud23]

I also try this also.but nothing to happen

I mean you have set 4800 baud rate in your controller and your gsm might be set at 9600 baud rate.check your gsm first with hyper terminal.

 

[Mani Yuvan]

I mean you have set 4800 baud rate in your controller and your gsm might be set at 9600 baud rate.check your gsm first with hyper terminal.

how to i check my gsm with Computer. And i used laptop so there is no DB9 port then how to i connect the gsm modem to computer. I also used windows7 os there is no Hyperterminal .Please any one guide me...

 

[milan.rajik]

If your SIM900 modem has 5V TTL Rx and Tx pins then you can use a TTL to USB adapter to connect SIM900 to PC USB port and then send AT commands with \r\n from some serial terminal software like Termite and see the responses from modem.

You have to connect RxD of TTL2USB to Tx of SIM900 and TxD of TTL2USB to Rx of SIM900 and GND of TTL2USB to GND of SIM900.

 

[Mani Yuvan]

Im using sim300 module but it also has the ttl option .

 

[milan.rajik]

If it is 5V TTL then you can interface it directly to your PIC16F or 18F.

 

[Mani Yuvan]

If it is 5V TTL then you can interface it directly to your PIC16F or 18F.

thanks milan. i successfully receive the message and call from the gsm modem. but it repeated continuously but i'm not use the while loop just i put the task in main function but checking Proteus it repeated again & again.

 

[milan.rajik]

Maybe you don't have a while(1); loop at the end of main() function and when program execution reaches the end of the main() it is resetting PIC and hence you see repeatation.

 

[Mani Yuvan]

thanks for your reply .i forgot to put the while(1); is there any way to connect the usb gsm modem to the pic18f452 microcontroller.

 

[milan.rajik]

If your SIM300 has 5V TTL pins then use it to connect it to PIC. USB pot of GSM is only to connect to PC.