ex6a_main.c

GCC arm startup example for beginners

/* ex6a_main.c */
#include "led.h"

/* ----------------------------------------------------------------
 * LPC2138 registers
 * ----------------------------------------------------------------
 */
#define PINSEL0      (*((volatile unsigned long *) 0xE002C000))
#define EXTINT       (*((volatile unsigned long *) 0xE01FC140))
#define EXTMODE      (*((volatile unsigned long *) 0xE01FC148))
#define EXTPOLAR     (*((volatile unsigned long *) 0xE01FC14C))
#define VICIntSelect (*((volatile unsigned long *) 0xFFFFF00C))
#define VICIntEnable (*((volatile unsigned long *) 0xFFFFF010))

/* ----------------------------------------------------------------
 * Function declarations and globals
 * ----------------------------------------------------------------
 */
void fiq_init();
void fiq_handler(void) __attribute__((interrupt("FIQ")));
static volatile int led_counter = 0;

/* ----------------------------------------------------------------
 * Function definitions
 * ----------------------------------------------------------------
 */

/* Setup the external interrupt and enable FIQ interrupts */
void fiq_init(void)
{
  /* Enable P0.14 EINT1 pin function: PINSEL0[29:28] = 10b */
  PINSEL0 = (2 << 28);

  /* Make EINT1 falling edge-sensitive
   * (level sensitive increments the LED count too fast)
   */
  EXTMODE  = 2;
  EXTPOLAR = 0;

  /* Clear register after mode change */
  EXTINT = EXTINT;

  /* Setup the VIC to have EINT1 generate FIQ
   * (EINT1 is interrupt source 15)
   */
  VICIntSelect = (1 << 15); /* Select FIQ */
  VICIntEnable = (1 << 15); /* Enable */
}

void fiq_handler(void)
{
	led_counter <<= 1;
	if (led_counter > 0x80) {
		led_counter = 1;
	}
	led(led_counter);

	/* Clear EXT1 interrupt flag */
	EXTINT = 2;
}

/* ----------------------------------------------------------------
 * Application
 * ----------------------------------------------------------------
 */
int main (void)
{
	led_init();
	led_counter = 1;
	led(led_counter);
	fiq_init();
	while(1);
	return 0;
}