led.c

arm汇编语言程序和其工具链的熟悉

/*
 *	led.c   -   led api & driver
 *	
 *	Author: 	li ming <[e-mail]>
 *	Date:		2008-4-16
 *	Copyleft:	http://www.lumit.org
 */
 
#include "led.h"

/* 
; hardware connection
; IO17 	IO04 	IO05 	IO06	(gpio)
; D6   	D7   	D8   	D9 	(led)
; so output value = 0x00020070 = (0b0000 0000  0000 0010  0000 0000  0111 0000)
*/

/* define the relative gpio register */
#define SYSCFG      0x03FF0000
#define IOPMOD		(*((volatile unsigned *)(SYSCFG+0x5000)))
#define IOPDATA		(*((volatile unsigned *)(SYSCFG+0x5008)))

/* set led related gpio */
int led_init(void)
{
	// set IOPMOD register mode bit to 1 = output ( refer to um_s3c4510b_rev1.pdf , page 12-2)
	IOPMOD = IOPMOD | 0x00020070;	
	
	// set IOPDATA register bit to 0 , initial led status = ALL_OFF
	IOPDATA = IOPDATA & (~0x00020070);	
	 
	return 0;
}

/* delay for about one second */
static void delay(int time)	
{
	int i, j;

	for(i = 0; i < time; i++)
		for(j = 0; j < 65536; j++)
			;
}
 
int led_on(int position)
{	
	// set IOPDATA register 
	switch(position)
	{
		case 0:				
			// buf[0] = IO 6
			IOPDATA |= 0x00000040 ;
			break;
		case 1:
			// buf[1] = IO 5
			IOPDATA |= 0x00000020 ;
			break;
		case 2:
			// buf[2] = IO 4
			IOPDATA |= 0x00000010 ;
			break;
		case 3:
			// buf[3] = IO 17
			IOPDATA |= 0x00020000 ;
			break;
		default:
			break;	
	}
		
	return 0;
}

int led_off(int position)
{
	 
	// set IOPDATA register 
	switch(position)
	{
		case 0:				
			// buf[0] = IO 6
			IOPDATA &= ~0x00000040 ;
			break;
		case 1:
			// buf[1] = IO 5
			IOPDATA &= ~0x00000020 ;
			break;
		case 2:
			// buf[2] = IO 4
			IOPDATA &= ~0x00000010 ;
			break;
		case 3:
			// buf[3] = IO 17
			IOPDATA &= ~0x00020000 ;
			break;
		default:
			break;	
	}	 
	
	return 0;	
}

void led_test(void)
{
	led_init();
	
	while(1)
	{
		led_on(0);
		led_on(1);
		led_on(2);
		led_on(3);
		
		delay(100);
		
		led_off(0);
		led_off(1);
		led_off(2);
		led_off(3);
		
		delay(100);
	}		
	return;
}