Interfacing GSM SIM900 with PIC18f26k22

[shubham]

Trying to recieve a message into the microcontroller via the GSM module and then display it using Hterm. Hterm is not displaying anyting. This is the code used. Can’t figure out where is it wrong.

 

 

#include<stdio.h>

#include<stdlib.h>

#include<delays.h>

#include<p18f26k22.h>

 

#pragma config FOSC=INTIO7

#pragma config WDTEN=OFF

#pragma config LVP=OFF

#pragma config DEBUG=OFF

 

void UART2(void)

{

    TXSTA2bits.BRGH=1;

    SPBRG2=51;

    TRISBbits.RB6=1;

    TRISBbits.RB7=1;

    RCSTA2bits.SPEN=1;

    TXSTA2bits.SYNC=0;

    TXSTA2bits.TXEN=1;

    RC2STAbits.CREN=1;

}

 

void UART1(void)

{

    TXSTA1bits.BRGH=1;

    SPBRG1=51;

    TRISCbits.RC6=1;

    TRISCbits.RC7=1;

    RCSTA1bits.SPEN=1;

    TXSTA1bits.SYNC=0;

    TXSTA1bits.TXEN=1;

    RC1STAbits.CREN=1;

}

 

void UART_sendbyte(unsigned char c)

{

    while(!TXSTA1bits.TRMT); /* Wait until TX buf read for new data */

    TX1REG = c;

}

void UART_sendstring(char *str)

{

while(*str != ‘’)

{

Delay1KTCYx(100);

while(!TXSTA1bits.TRMT);

TX1REG = *str;

str++;

}

}

 

void UART2_sendstring(char *str)

{

while(*str != ‘n’)

{

Delay1KTCYx(100);

while(!TXSTA2bits.TRMT);

TX2REG = *str;

str++;

}

}

 

unsigned char *UART_getstring()

{

    unsigned char *strng;

    int i=0;

while(strng!=13)

{

            if(PIR1bits.RC1IF)

            {

                strng=RC1REG;

                i++;

            }

        }

    strng=’’;

    return strng;

}

 

void main()

{

    unsigned char *cmd, *msg, c;

    UART1();       //This is to be used for communicating with the GSM module via Tx1 Rx1

    UART2();      //This is to be used for communicating with the Hterm via Tx2 Rx2

    Delay10KTCYx(200);

    UART_sendbyte(‘r’);

    Delay10KTCYx(100);

    sprintf(cmd,”AT+CMGR=1″);

    UART_sendbyte(‘r’);

    Delay10KTCYx(200);

    UART_sendstring(cmd);

    UART_sendbyte(‘r’);

    Delay10KTCYx(200);

    msg=UART_getstring();

    Delay10KTCYx(200);

    UART2_sendstring(msg);

}

 

 

[AJISH ALFRED]

Hi Shubham,

The codem for sending string may or maynot work depends on the compiler. Some compiler requires ” const char * “, like

“void UART_sendstring(const char *str)”.

 

Try to send a readable ascii character using UART_sendbyte(), like

UART_sendbyte(‘A’);

 

Also make sure that the serial port settings like the baud rate, start bit, stop bit etc. are same on both the sides.

[Author]

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