Yes i have tested my code without modem also. It works fine.

Not exactly but nearly about after every 6-9 seconds i am sending "AT" command

1.Are you able to receive data properly? i mean only receiving data packet from your GPRS device?

Not always. But sometimes i get "AT" reply from modem.I have tested this code on Hyper Terminal (instead of GPRS modem) it works fine. Sometime it also fails.

Hi.

In the source code I am just sending "AT" command and trying to check its "OK" response.

My code is....

#include <sys/types.h>

#include <sys/stat.h>

#include <fcntl.h>

#include <termios.h>

#include <stdio.h>

#include<sys/signal.h>

#include<sys/ioctl.h>

        

#define BAUDRATE 	B9600

#define Modem		"/dev/ttyAM1"

#define _POSIX_SOURCE 1 /* POSIX compliant source */

#define FALSE 0

#define TRUE 1



/********************************************  Functions Prototype  *****************************************************/

void Modem_Interface(void);

void sig_handler(int status);

void serial_cnfg(void);

void modemdelay(void);     

void modemdelay1(void);



/*************************************************************************************************************************/



/*************************************************  Structures  **********************************************************/

struct termios oldtio,newtio;

struct termios oldtio1,newtio1;



/*************************************************************************************************************************/



/**********************************************  Global Variables  *******************************************************/



int FD_Printer, FD_Modem, FD_CM;

unsigned char sig_flag;

int data;

int fd,cashfd,c, res,cntr=0,virus=0;

unsigned int CM_rply_Cntr=0;

char CM_rply_Buf[250];

char rx_data,rx_cntr=0;



/*************************************************************************************************************************/





void sig_handler(int status)

{

	read(FD_Modem,&rx_data,1);

	//read(FD_Modem,CM_rply_Buf,100);

	//CM_rply_Buf[rx_cntr++]=rx_data; 

	printf("rx_data=%c\n",rx_data);

}





void modemdelay(void)

{

	unsigned int i=0,j;

	for(i=0;i<5632;i++)

		for(j=0;j<4234;j++);

}



void modemdelay1(void)

{

	unsigned int i=0,j;

	for(i=0;i<632;i++)

		for(j=0;j<234;j++);

}







void serial_cnfg(void)

{

	struct sigaction sa;

	

	sa.sa_handler	= sig_handler;

	sa.sa_flags	= 0;

	sa.sa_restorer	= NULL;

	

	sigemptyset(&sa.sa_mask);

	sigaction(SIGIO,&sa,NULL);

	

	fcntl(FD_Modem,F_SETOWN,getpid());

      fcntl(FD_Modem,F_SETFL,FASYNC);

}



void Modem_Interface(void)

  {

       

	char cmd[]="AT",data,enter=0x0D;

	unsigned int i=0;

	printf("Transmitting \n");

	while(cmd!='\0')

	{

		data=cmd[i++];

		write(FD_Modem,&data,1);

	}



	write(FD_Modem,0x0D,1);

}





int main(void)

{

	unsigned int i;

	

	while(1)

      {	

       	

	  FD_Printer = open(Printer, O_WRONLY | O_NOCTTY );                 

        if (FD_Printer <0) {perror(Printer); exit(-1); }

        

	  FD_Modem = open(Modem, O_RDWR | O_NOCTTY );                 //for modem

        if (FD_Modem <0) {perror(Modem); exit(-1); }

        

        serial_cnfg();

      

        tcgetattr(FD_Modem,&oldtio); 

        bzero(&newtio, sizeof(newtio));

        

        newtio.c_cflag       = BAUDRATE | CRTSCTS | CS8 | CLOCAL | CREAD;

        newtio.c_iflag 	     = IGNPAR; 

        newtio.c_oflag 	     = 0;

        newtio.c_lflag       = 0;   /* set input mode (non-canonical, no echo,...) */

        newtio.c_cc[VTIME]   = 2;   /* inter-character timer unused */

                

        tcflush(FD_Modem, TCIFLUSH);

        tcsetattr(FD_Modem,TCSANOW,&newtio);

        

        modemdelay();  

              	

        for(i=0;i<248;i++)

        	CM_rply_Buf='\0';

        		

        rx_cntr=0;

        rx_data='\0';

	

        //printf("\nIn Modem_Interface");

        Modem_Interface();



	  modemdelay();  

	  modemdelay(); 

			

 	}

      

	  tcsetattr(FD_Modem,TCSANOW,&oldtio);

    	  return 0;

                

 

}

I am using wavecom GPRS ( Q24PL002) modem, with 9600 baud rate. I am setting everything in while loop beacuse whenever i used while(1) for only command transmission after some time signal handler did not worked.

Thanks for your suggestion.

I have also one more problem in signal handling. I have connected a GPRS modem to UART1 (serial port).
In the code i am just sending "AT" command continuously and trying to check its reply. But problem is that sometimes I get reply "OK" and sometimes not.

Also after some time my code is does not get interrupted even though there is reply from modem.. I have checked this using Hyper Terminal.

Please help me out what is the prolem?

Hi all,

I have 3 different devices Dev1, Dev2 & Dev3 connected to UART 1, UART 2 & UART 3 respectively. I am using these 3 devices alternatively.
I want to write signal handler for these 3 devices interrupts. I am able to handle one signal handler at a time.

But problem is that when I have tried to write signal handler for other (means two signal handler at a time for SIGIO signal), my programs does not work.

Can anybody tell me how to solve this problem?

Please help me.

Thanks

Hi all,

I am trying to display the characters getting from keyboard, on screen.
Currently i am using TS 7260 board (linux ported on it) with PC/104 bus. I can access PC/104 bus with 8/16 bit mode.
I am able to display images on the screen (size 640 X 480), but not characters.

Can anybody help me how to do it? Please help me.

Thank you.

Thank You very much for your reply:) .
I got solution for serial programming in terminos.h.

Hi all,

I am writing code for reading & writing the data from serial port (UART of ARM Processor).
But i am facing a problem in reading.

As written in man page the read() call returns the character till it will get "Enter/Carriage return" or "EOF". I am interfacing the GPRS modem on this serial port. So from Modem there is no way to get me "Enter/Carriage return" or "EOF".

Because of this read() gets blocked.

Is there any other way to just read the received characters without EOF & returns that characters?

Please help me for this.