pwm.c

MEGA16 开发包3

#include <iom16v.h> 
#include <macros.h> 

#define PWM0     PORTB3  //OC0   PB3

volatile unsigned char T0OCR;       //设置T0的时间值

/*相位修正模式输出方波,64分频*/
void timer0_init(void) 
{
 OCR0  = T0OCR;       //设定TOP
                      // TOP=8000000/(2*64*1000)-1=61.5  选61  1.008KHz(0.992mS)
                      // TOP=8000000/(2*64*2000)-1=30.25 选30  2.016KHz(0.496ms)
 TCCR0 = (0<<WGM01)|(1<<WGM00)|(1<<COM01)|(0<<COM00)|(0<<CS02)|(1<<CS01)|(1<<CS00);
}

void main(void)
{
                                //上电默认DDRx=0x00,PORTx=0x00 输入，无上拉电阻
    PORTA =0xFF;                //不用的管脚使能内部上拉电阻。
    PORTC =0xFF;
    PORTB =~ (1<<PWM0);         
    DDRB  =  (1<<PWM0);         

    T0OCR=0x40;                       //改变此值即可改变输出方波的占空比
    timer0_init();
    SEI();                          //使能全局中断
}