2019年09月25日 | STM32一个定时器输出不同频率

1个定时器输出4路频率相同，占空比不同的PWM比较容易实现，只需要改变每个通道的比较值就可以了

要想输出频率不同，占空比相同，需要用到比较模式，当比较成功IO翻转。

同时还需要用到定时器中断去重新设置比较值。

稍微解释下面语句：

Period是计数值

prescaler是对总线时钟的分频

这个函数是设置比较值

基本要点是理解上面这些。没接触过定时器的会比较抽象，不能理解。

下面直接上代码吧

定时器初始化：

u16 capture = 0;

vu16 CCR1_Val = 32768;

vu16 CCR2_Val = 16384;

vu16 CCR3_Val = 8192;

vu16 CCR4_Val = 4096;

void PWM1_Init(u16 arr,u16 psc)

{

GPIO_InitTypeDef GPIO_InitStructure;

    TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

    TIM_OCInitTypeDef  TIM_OCInitStructure;

    TIM_BDTRInitTypeDef TIM_BDTRInitStructure;

//开启时钟

    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA,ENABLE);       //使能GPIO和服用功能时钟

//初始化GPIO

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1|GPIO_Pin_2|GPIO_Pin_3;    //PWM输出在PA8,9,10

    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;                     //复用推挽输出

    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

    GPIO_Init(GPIOA,&GPIO_InitStructure);                               //初始化GPIO

NVIC_InitTypeDef NVIC_InitStructure;

NVIC_InitStructure.NVIC_IRQChannel=TIM2_IRQn;

NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority=0;

NVIC_InitStructure.NVIC_IRQChannelSubPriority=1;

NVIC_InitStructure.NVIC_IRQChannelCmd=ENABLE;

NVIC_Init(&NVIC_InitStructure);

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

TIM_TimeBaseStructure.TIM_Period = 65535;       

TIM_TimeBaseStructure.TIM_Prescaler = 2;     

TIM_TimeBaseStructure.TIM_ClockDivision = 0; 

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;

TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle;      //PWM模式

TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable; //正向通道有效

TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low;    //输出极性

TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;

TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

TIM_OCInitStructure.TIM_Pulse = CCR1_Val;        //占空时间

TIM_OC1Init(TIM2,&TIM_OCInitStructure);        //通道1

TIM_OC1PreloadConfig(TIM2, TIM_OCPreload_Disable);

TIM_OCInitStructure.TIM_Pulse = CCR2_Val;        //占空时间

TIM_OC2Init(TIM2,&TIM_OCInitStructure);        //通道2

TIM_OC2PreloadConfig(TIM2, TIM_OCPreload_Disable);

TIM_OCInitStructure.TIM_Pulse = CCR3_Val;        //占空时间

TIM_OC3Init(TIM2,&TIM_OCInitStructure);        //通道3

TIM_OC3PreloadConfig(TIM2, TIM_OCPreload_Disable);

TIM_OCInitStructure.TIM_Pulse = CCR4_Val;        //占空时间

TIM_OC4Init(TIM2,&TIM_OCInitStructure);        //通道4

TIM_OC4PreloadConfig(TIM2, TIM_OCPreload_Disable);

TIM_Cmd(TIM2,ENABLE);

TIM_ITConfig(TIM2, TIM_IT_CC1 | TIM_IT_CC2 | TIM_IT_CC3 | TIM_IT_CC4, ENABLE);

}

定时器中断：

extern "C" void TIM2_IRQHandler(void)

{

if (TIM_GetITStatus(TIM2, TIM_IT_CC1) != RESET)

{

TIM_ClearITPendingBit(TIM2, TIM_IT_CC1 );

capture = TIM_GetCapture1(TIM2);

TIM_SetCompare1(TIM2, capture + CCR1_Val );

}

if (TIM_GetITStatus(TIM2, TIM_IT_CC2) != RESET)

{

TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);

capture = TIM_GetCapture2(TIM2);

TIM_SetCompare2(TIM2, capture + CCR2_Val);

}

if (TIM_GetITStatus(TIM2, TIM_IT_CC3) != RESET)

{

TIM_ClearITPendingBit(TIM2, TIM_IT_CC3);

capture = TIM_GetCapture3(TIM2);

TIM_SetCompare3(TIM2, capture + CCR3_Val);

}

if (TIM_GetITStatus(TIM2, TIM_IT_CC4) != RESET)

{

TIM_ClearITPendingBit(TIM2, TIM_IT_CC4);

capture = TIM_GetCapture4(TIM2);

TIM_SetCompare4(TIM2, capture + CCR4_Val);

}

}

主函数：

通道4先按10的比较值运行，具体频率未测，如果按1000的比较值运行，具体频率未测，实测效果

频率输出要做线性修正，没时间去研究，有空在完善。