main.c

Program to blink the led for AT91RM9200-EK board.

/*
*
* Sample application to toggle LED on KB9202
*  Notice that the kernel may provide LED access functions,
*  but the point of this program is to provide an example
*  on how to access the AT91RM9200 system controller for the purpose
*  of driving GPIO and other peripheral functions.
*
* Copyright (C) 2008 KwikByte <www.kwikbyte.com>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
* or visit http://www.gnu.org/copyleft/gpl.html
*
* 26MAR2008 	Initial creation (KwikByte)
*/

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <sys/shm.h>

#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <unistd.h>
#include <fcntl.h>
#include <strings.h>
#include <string.h>
#include <time.h>

#include "AT91RM9200.h"

/* ********************** LOCAL DEFINES ****************************** */
#define	LED_MAX			3

/* D20 = top LED
 * D19 = middle LED
 * D18 = bottom LED
 *
 * Notice that D16..D31 are muxed with PC pins
 *
 * see AT91RM9200 datasheet for more information
 */
static unsigned ledSignalMapping[] = 
	{
	AT91C_PIO_PC20,
	AT91C_PIO_PC19,
	AT91C_PIO_PC18
};

#define	GPIO_LED_MASK			(AT91C_PIO_PC20 | AT91C_PIO_PC19 |\
								 AT91C_PIO_PC18)

static int					memMapFile;
static AT91PS_SYS			at91SysCtrlr;

/* ************************ UTILITY FUNCTIONS ******************************* */


/*
 * Set the LED output(s)
 */
static void UpdateLED(unsigned ledIndex, unsigned on)
{
	if (ledIndex >= LED_MAX)
		/* invalid index */
		return ;

	/* remember that LED signals are active low */
	if (on)
	{
		at91SysCtrlr->PIOC_CODR = (ledSignalMapping[ledIndex]);
	}
	else
	{
		at91SysCtrlr->PIOC_SODR = (ledSignalMapping[ledIndex]);
	}
	/* do not worry about sync */
}


/* *************** HARDWARE SUPPORT FUNCTIONS ************************ */


/*
 * Access the hardware
 */
static int OpenSystemController(void)
{
	if ((memMapFile = open("/dev/mem", O_RDWR | O_SYNC)) < 0)
	{
		printf("ERROR: Unable to open /dev/mem\n");
		return (errno);
	}

	at91SysCtrlr = mmap(NULL, 4096, PROT_READ | PROT_WRITE,
		MAP_SHARED, memMapFile, (unsigned)AT91C_BASE_SYS);

	if (at91SysCtrlr == MAP_FAILED)
	{
		printf("ERROR: Unable to mmap the system controller\n");
		close (memMapFile);
		memMapFile = -1;
		return (errno);
	}

	/* set LED signals for output */
	/* set digital output ports init value = all on (active low) */
	at91SysCtrlr->PIOC_CODR		= GPIO_LED_MASK;
	at91SysCtrlr->PIOC_PPUDR	= GPIO_LED_MASK;
	at91SysCtrlr->PIOC_PER		= GPIO_LED_MASK;
	at91SysCtrlr->PIOC_OER		= GPIO_LED_MASK;

	/* do not worry about sync */
	return (0);
}


/* ************************ MAIN LOOPS ******************************* */


int main(int argc, char **argv)
{
	unsigned	ledIndex;

	if (OpenSystemController())
	{
		printf("Unable to map hardware resources\n");
		return (-1);
	}

	ledIndex = 0;
	while (1)
	{
		/* loop forever toggling LEDs at 1 second interval */

		/* turn on */
		UpdateLED(ledIndex, 1);
		printf ("LED %d is now on\n", ledIndex);

		/* wait for 0.5 seconds */
		usleep(500000);

		/* turn off */
		UpdateLED(ledIndex, 0);
		printf ("LED %d is now off\n", ledIndex);

		/* wait for 0.5 seconds */
		usleep(500000);

		/* reset index to first LED if we finished all of them */
		if (++ledIndex >= LED_MAX)
			ledIndex = 0;
	}

	return (0); /* never get here */
}