[crisos] GPIO and Interrupt

[Mike Lawson <crisos@xxxxxxxxx>]

Hi all,

I use the Foxboard (FoxGM) with the alpha firmware for a project at school. Is
there a possibility to monitor the button press (or any GPIO ports/pins
configured as digital input) without polling it?

At the moment I do the following

/** readbuttons  **
 * \brief   monitors one of the two buttons on the FOX Board
 *
 * \param   button   bit number of the GPIO pin where the button is connected
 * \param   timeout   amount of seconds to monitor the button
 * \return   state of button on press or after timeout
 */
int read_buttons(int button, int timeout){
	int value=0, start=0;
	int retval=0;
	int fd=-1;

	int t_elapsed, t_rest;
	struct timeval T[2];

	if ((fd = open("/dev/gpiog", O_RDWR))<0) {
		fprintf(stderr, "failed to open /dev/gpiog \n");
		return -1;
	}
	
	// get initial state
	start = button & ioctl(fd, _IO(ETRAXGPIO_IOCTYPE, IO_READBITS));
	
	gettimeofday(&T[0],NULL);

	do{ // do until button pressed or timeout occured
		value= button & ioctl(fd, _IO(ETRAXGPIO_IOCTYPE, IO_READBITS));
		retval = (value == start ) ? 0 : 1;
		
		usleep(100000);
		gettimeofday(&T[1],NULL);
		
		t_elapsed = T[1].tv_sec -T[0].tv_sec;
		t_rest = timeout-t_elapsed;

	}while((t_elapsed < timeout) && (retval == 0));

	close(fd);
	return retval;
}

Any better solution is highly appreciated!
Thanks a lot and best regards,

Mike


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