/* *********************************************
 * File name: timer_16bit_test.c
 * Function:  16位定时器比较匹配中断方式测试程序
 * Description: 定时器控制LED以500ms间隔闪烁
 * Author & Date: Joshua Chan, 2012/03/26
 * *********************************************/
#include 
#include 
#include 
#include 
#include 
#include "timer_16bit_test.h"

/* 配置16位定时器timer1比较匹配中断使能 */
void timer1_comp_init(void)
{
    TCCR1A = 0x00; /* CTC模式, 通道A普通端口操作, 预分频1024 */
    TCCR1B = 0x0D;
    TCCR1C = 0x00;
    TIMSK |= 0x10; /* 输出比较A匹配中断使能 */
    OCR1A =0x1E83; /* 中断发生间隔 (0x1E83+1)*1024*(1/16.0MHz)*1000 = 500ms */
    TCNT0 = 0x00;
}

/* 配置LED管脚为输出 */
void set_pb0_output(void)
{
    DDRB |= 0x01;
}

/* LED亮 */
void set_pb0_low(void)
{
    PORTB &= ~(0x01);
}

/* LED灭 */
void set_pb0_high(void)
{
    PORTB |= 0x01;
}

/* 检测LED状态 */
unsigned char pb0_is_high(void)
{
    return (PORTB & 0x01);
}

/* 定义timer1比较匹配中断处理函数 */
#pragma vector = TIMER1_COMPA_vect
__interrupt void timer1_isr(void)
{
    if (pb0_is_high())
        set_pb0_low();
    else        
        set_pb0_high();
}