ATMega8 PWM 功能(T/C 1)测试程序

#include#include#define uchar unsigned char#define uint unsigned int#define FREQ 4//延时void DelayMs(uint ms){     uint i;     for(i=0;i         _delay_loop_2(FREQ * 250);}int main (void){     uchar direction=1;     uchar pwm=0;          //      8位相位修正PWM模式     //      OC1A 向上计数过程中比较匹配时清零     //      向下计数过程中比较匹配时置位     //      时钟源：4MHz/64 PWM频率：4MHz/(64*256)=122Hz     TCCR1A=_BV(COM1A1)|_BV(WGM10);     TCCR1B=_BV(CS11)|_BV(CS10);               TCNT1=0;     DDRB|=_BV(PB1);//OC1A pwm输出引脚允许     //循环改变PWM输出脉宽，使接在OC1A引脚上的发光管亮度发生变化  while(1)     {          if(direction)           {              if(++pwm==254)                direction=0;           }          else           {              if(–pwm==0)                direction=1;           }           OCR1A=pwm;           //OCR1B=pwm;           DelayMs(10);     }   return 0;}