/*任意週期和任意佔空比DUTY%的PWM*/

#define CYCLE 6000L //定義PWM週期(最大值為32767)

sbit PWM2=P3^7;

sbit PWM3=P2^1;

sbit PWM4=P2^2;

void pwminit()

{ P_SW2 |= 0x80;

PWMCFG = 0x00; //配置PWM的輸出初始電平為低電平

PWMCKS = 0x0f; //選擇PWM的時鐘為Fosc/(0+1)

PWMC = CYCLE; //設定PWM週期,定義PWM週期(最大值為32767)

PWM2CR = 0x00; //選擇PWM2輸出到P3.7,不使能PWM2中斷

PWM3CR = 0x00;

PWM4CR = 0x00;

PWM2T1 = 0x0001;

PWM2T2 = 0;

PWM3T1 = 0x0001;

PWM3T2 = 0;

PWM4T1 = 0x0001;

PWM4T2 = 0;

PWMCR |= 0x80; //使能PWM模組

P_SW2 &=~0x80;

}

void pwm2( unsigned int DUTY) //PWM2

{

if(DUTY==0)

{

PWMCR &=~0x01;

PWM2=0;

}

else if (DUTY==100)

{

PWMCR &=~0x01;

PWM2=1;

}

else

{

P_SW2 |= 0x80; //使能訪問PWM在擴充套件RAM區的特殊功能暫存器XSFR

PWM2T1 = 0x0001; //設定PWM2第1次反轉的PWM計數

PWM2T2 = CYCLE * DUTY / 100; //設定PWM2第2次反轉的PWM計數

P_SW2 &=~0x80; //佔空比為(PWM2T2-PWM2T1)/PWMC

PWMCR |= 0x01; //使能PWM訊號輸出

}

}

void pwm3(unsigned int DUTY) //PWM3

{

if(DUTY==0)

{

PWMCR &=~0x02;

PWM3=0;

}

else if(DUTY==100)

{

PWMCR &=~0x02;

PWM3=1;

}

else

{

P_SW2 |= 0x80;

PWM3T1 = 0x0001;

PWM3T2 = CYCLE * DUTY / 100;

P_SW2 &=~0x80;

PWMCR |= 0x02;

}

}

void pwm4(unsigned int DUTY) //PWM4

{

if(DUTY==0)

{

PWMCR &=~0x04;

PWM4=0;

}

else if (DUTY==100)

{

PWMCR &=~0x04;

PWM4=1;

}

else

{

P_SW2 |= 0x80;

PWM4T1 = 0x0001;

PWM4T2 = CYCLE * DUTY / 100;

P_SW2 &=~0x80;

PWMCR |= 0x04;

}

}