lpc1768的PWM使用

//p2.0 pwm1.1

void ALS_Init(void)     //初始化

{

    LPC_SC->PCONP |= (1<<1)|(1<<2)|(1<<15);//打开时钟

    LPC_SC->PCLKSEL0 &= ~(3<<2);    //时钟25M

    LPC_SC->PCLKSEL0 &= ~(3<<4);

    //p2.0

    LPC_PINCON->PINSEL4 &= ~(0X03L<<0);     //GPIO

    LPC_PINCON->PINMODE4 &= ~(0X03L<<0);    //使能上拉

    LPC_PINCON->PINMODE_OD2 &= ~(0X01<<1);  //推挽正常模式

    P2dir(0) = 1;//输出

    LPC_TIM1->TCR |= (1<<1);                        //复位定时器

    LPC_TIM1->CTCR = 0x00;                          //定时器模式

    LPC_TIM1->PC = 0X00;

    LPC_TIM1->PR   = 25-1;                          //预分频,计数频率1m

    LPC_TIM1->MR0  = 20;                            //25*100  2500 频率10K

    LPC_TIM1->MR1  = 100;

    LPC_TIM1->MCR |= ((1<<0)|(1<<3)|(1<<4));                //MR0与TC值匹配时将产生复位 产生中断 MR1匹配时产生中断 不复位

    LPC_TIM1->IR  |= 0XFF;                          //清所有中断标志位

    LPC_TIM1->TCR  = (1<<0);                        //启动定时器

    NVIC_EnableIRQ(TIMER1_IRQn);                   

}

void ALS_Set_Duty(u8 duty)      //设置占空比

{

    LPC_TIM1->TCR  = 0;                     //暂停定时器

    if(duty >= 100)duty = 99;

    if(duty == 0)duty = 1;

    LPC_TIM1->MR0 = duty;

    LPC_TIM1->TCR  = (1<<0);                        //启动定时器

}

void ALS_Stop(void)

{

    LPC_TIM1->TCR  = 0;                     //暂停定时器

    P2low(0) = 1;                           //电平恒定

}

void TIMER1_IRQHandler(void)

{

    NVIC_ClearPendingIRQ(TIMER1_IRQn);

    if( LPC_TIM1->IR &0x01) //mr0中断

    {

        P2low(0) = 1;

        LPC_TIM1->IR |= (1<<0);         //清中断标志

    }

    else if(LPC_TIM1->IR &0x02)

    {

        P2high(0) = 1;

        LPC_TIM1->IR |= (1<<1);         //清中断标志

    }

}