STC单片机PWM的实现

08

2月

STC单片机PWM的实现

PWM波是数字向模拟转换的一种重要方法，通常使用单片机的定时器做频率发生器，含有数字比较器，当设定值与定时器的值相等，引脚的电平发生翻转。控制设定值，就控制了PWM波占空比，通过滤波，输出直流模拟量。

#include

sfr CCON =0xD8;

sfr CMOD =0xD9;

sfr CCAPM0 =0xDA;

sfr CCAPM1 =0xDB;

sfr CCAPM2 =0xDc;

sfr CCAPM3 =0xDd;

sfr CL =0xE9;

sfr CH =0xF9;

sfr CCAP0L =0xEA;

sfr CCAP0H =0xFA;

sfr CCAP1L =0xEb;

sfr CCAP1H =0xFb;

sfr CCAP2L =0xEc;

sfr CCAP2H =0xFc;

sfr CCAP3L =0xEd;

sfr CCAP3H =0xFd;

sbit CR =0xDE;

void init_pwm()

{

//定时器的来源CPS1,CPS0

CMOD=0x02;//Setup PCA timer

CL=0x00;

CH=0x00;

}

//控制占空比

void pulse_0(unsigned char p_on)

{

CCAP0L=p_on;//Set the initial value same as CCAP0H

CCAP0H=p_on;//

//CCAPMn.1使能脉宽调制模式，EC0M必须=1

CCAPM0=0x42;//0100,0010 Setup PCA module 0 in PWM mode

}

void pulse_1(unsigned char p_on)

{

CCAP1L=p_on;//Set the initial value same as CCAP0H

CCAP1H=p_on;//25% Duty Cycle

//CCAPMn.1使能脉宽调制模式，EC0M必须=1

CCAPM1=0x42;//0100,0010 Setup PCA module 0 in PWM mode

}

void pulse_2(unsigned char p_on)

{

CCAP2L=p_on;//Set the initial value same as CCAP0H

CCAP2H=p_on;//25% Duty Cycle

//CCAPMn.1使能脉宽调制模式，EC0M必须=1

CCAPM2=0x42;//0100,0010 Setup PCA module 0 in PWM mode

}

void pulse_3(unsigned char p_on)

{

CCAP3L=p_on;//Set the initial value same as CCAP0H

CCAP3H=p_on;//25% Duty Cycle

//CCAPMn.1使能脉宽调制模式，EC0M必须=1

CCAPM3=0x42;//0100,0010 Setup PCA module 0 in PWM mode

}

void delay(int a)

{

int i;

for(i=0;i}

void main(void)

{

unsigned char i=0;

init_pwm();

CR=1; //Start PCA Timer

while(1)

{

while(++i)

{

pulse_0(i+50);

pulse_1(i+100);

pulse_2(i+150);

pulse_3(i+200);

delay(1000);

}

while(--i)

{

pulse_0(i+50);

pulse_1(i+100);

pulse_2(i+150);

pulse_3(i+200);

delay(1000);

}

}

}