PWM控制LED源代码

// Cpu ATTiny13

// 频率: 内部9.6000Mhz 不分频

// winavr gcc 优化级别O0

#include

#define nop() __asm__ __volatile__("nop") //空语句

unsigned char PWM[]={0x20,0x40,0x60,0x80,0xA0,0xC0,0xE0,0xFF};

unsigned char PWMON;

unsigned char PWMVal;

//IO引脚初始化　

void port_init(void)

{

PORTB = 0x08; //PB3接按键设置为输出上拉

DDRB = 0x37; //PB0为PWM输出　上电置0

}

//Timer0初始化

//快速PWM模式　频率37.500KHz

void timer0_init(void)

{

OCR0A = 0x00;

TCNT0 = 0x01; //设计数

TCCR0A = 0x03; //设置Timer0为快速PWM模式

TCCR0B = 0x01; //启动Timer0

}

//延时N毫秒

void delay_ms(void)

{

unsigned char TempCycA;

unsigned char TempCycB;

for (TempCycA=0; TempCycA<10; TempCycA++)

for (TempCycB=0; TempCycB<90; TempCycB++)

nop();

}

//主函数

int main(void)

{

unsigned int tempval=0;

unsigned int keytime=0;

port_init();

timer0_init();

PWMON = 1; //初始为PWM开启

PWMVal = 0; //第一档

OCR0A = PWM[PWMVal]; //更改占空比

TCCR0A = 0x83; //开启PWM

while(1)

{

if (!(PINB&0x08))

{

keytime = 0;

for (tempval=0; tempval<4000; tempval++)

{

if (!(PINB&0x08)) //键采样、防抖

{

keytime++;

delay_ms();

}

else

break;

}

}

if (PWMON) //PWM开启的状态下

{

if ((keytime>100)&&(keytime<1000)) //短按100－1000ms则调节

{

PWMVal++;

if (PWMVal>7) //循环

PWMVal = 0;

keytime = 0;

OCR0A = PWM[PWMVal]; //更改占空比

}

if (keytime>2999) //长按3秒则关

{

PWMON = 0;

keytime = 0;

TCCR0A = 0x03; //关闭PWM

delay_ms(); //延时

}

}

else //PWM关闭的状态下

{

if (keytime>2999) //长按3秒则开

{

PWMON = 1;

keytime = 0;

TCCR0A = 0x83; //开启PWM

}

}

}

}