Question

怎么用STM32配置产生PWM

Answer 1

STM32产生PWM是非常的方便的，要需要简单的设置定时器，即刻产生！当然，简单的设置对于新手来讲，也是麻烦的，主要包括：
（1）使能定时器时钟：

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
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（2）定义相应的GPIO：

/* PA2,3,4,5,6输出->Key_Up,Key_Down,Key_Left,Key_Right,Key_Ctrl */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2|GPIO_Pin_3|GPIO_Pin_4|GPIO_Pin_5|GPIO_Pin_6;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; //下拉接地，检测输入的高电平

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //50M时钟速度

GPIO_Init(GPIOA, &GPIO_InitStructure);

/* PA7用于发出PWM波,即无线数据传送 */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_7;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //50M时钟速度

GPIO_Init(GPIOA, &GPIO_InitStructure);
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（3）如果是产生PWM（频率不变，占空比可变），记得打开PWM控制，在TIM_Configuration()中。

TIM_Cmd(TIM3,ENABLE);

/* TIM1 Main Output Enable */

TIM_CtrlPWMOutputs(TIM1,ENABLE);
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利用定时器产生不同频率的PWM
有时候，需要产生不同频率的PWM，这个时候，设置与产生相同PWM的程序，有关键的不一样。
（一） 设置的原理
利用改变定时器输出比较通道的捕获值，当输出通道捕获值产生中断时，在中断中将捕获值改变，这时， 输出的I/O会产生一个电平翻转，利用这种办法，实现不同频率的PWM输出。
（二）关键设置
在定时器设置中：

TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Disable);
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在中断函数中：

if (TIM_GetITStatus(TIM3, TIM_IT_CC2) != RESET)

{

TIM_ClearITPendingBit(TIM3, TIM_IT_CC2);

capture = TIM_GetCapture2(TIM3);

TIM_SetCompare2(TIM3, capture + Key_Value);

}
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一个定时器四个通道，分别产生不同频率（这个例子网上也有）

vu16 CCR1_Val = 32768;

vu16 CCR2_Val = 16384;

vu16 CCR3_Val = 8192;

vu16 CCR4_Val = 4096;void TIM_Configuration(void)

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

TIM_OCInitTypeDef TIM_OCInitStructure;

/* TIM2 clock enable */

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

/* ---------------------------------------------------------------

TIM2 Configuration: Output Compare Toggle Mode:

TIM2CLK = 36 MHz, Prescaler = 0x2, TIM2 counter clock = 12 MHz

CC1 update rate = TIM2 counter clock / CCR1_Val = 366.2 Hz

CC2 update rate = TIM2 counter clock / CCR2_Val = 732.4 Hz

CC3 update rate = TIM2 counter clock / CCR3_Val = 1464.8 Hz

CC4 update rate = TIM2 counter clock / CCR4_Val = 2929.6 Hz

--------------------------------------------------------------- *//* Time base configuration */

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);/* Channel 1 Configuration in PWM mode */

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle; //PWM模式2

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

TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;//反向通道无效

TIM_OCInitStructure.TIM_Pulse = CCR1_Val; //占空时间

TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low; //输出极性

TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High; //互补端的极性

TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;

TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;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);

/* TIM2 counter enable */

TIM_Cmd(TIM2,ENABLE);

/* TIM2 Main Output Enable */

//TIM_CtrlPWMOutputs(TIM2,ENABLE);/* TIM IT enable */

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

{

GPIO_InitTypeDef GPIO_InitStructure;/*允许总线CLOCK,在使用GPIO之前必须允许相应端的时钟.

从STM32的设计角度上说,没被允许的端将不接入时钟,也就不会耗能,

这是STM32节能的一种技巧,*/

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOA, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOC, ENABLE);

RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOD, ENABLE);

/* PA2,3,4,5,6,7输出->LED1,LED2,LED3,LED4,LED5,LED6 */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_2|GPIO_Pin_3|GPIO_Pin_4|GPIO_Pin_5|GPIO_Pin_6|GPIO_Pin_7;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_OD; //开漏输出

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //50M时钟速度

GPIO_Init(GPIOA, &GPIO_InitStructure);

/* PB0,1输出->LED7,LED8*/

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_Out_OD; //开漏输出

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz; //50M时钟速度

GPIO_Init(GPIOB, &GPIO_InitStructure);

/* PA0,1->KEY_LEFT,KEY_RIGHT*/

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0|GPIO_Pin_1;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; //上拉输入

GPIO_Init(GPIOA, &GPIO_InitStructure);/* PC13->KEY_UP*/

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; //上拉输入

GPIO_Init(GPIOC, &GPIO_InitStructure);/* PB5->KEY_DOWN*/

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_IPU; //上拉输入

GPIO_Init(GPIOB, &GPIO_InitStructure);/* GPIOA Configuration:TIM2 Channel1, 2, 3 and 4 in Output */

GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3;

GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;GPIO_Init(GPIOA, &GPIO_InitStructure);

}void NVIC_Configuration(void)

{

NVIC_InitTypeDef NVIC_InitStructure;/* Configure one bit for preemption priority */

NVIC_PriorityGroupConfig(NVIC_PriorityGroup_1);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);

}u16 capture = 0;

extern vu16 CCR1_Val;

extern vu16 CCR2_Val;

extern vu16 CCR3_Val;

extern vu16 CCR4_Val;void TIM2_IRQHandler(void)

{/* TIM2_CH1 toggling with frequency = 183.1 Hz */

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

{

TIM_ClearITPendingBit(TIM2, TIM_IT_CC1 );

capture = TIM_GetCapture1(TIM2);

TIM_SetCompare1(TIM2, capture + CCR1_Val );

}

/* TIM2_CH2 toggling with frequency = 366.2 Hz */

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

{

TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);

capture = TIM_GetCapture2(TIM2);

TIM_SetCompare2(TIM2, capture + CCR2_Val);

}/* TIM2_CH3 toggling with frequency = 732.4 Hz */

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

{

TIM_ClearITPendingBit(TIM2, TIM_IT_CC3);

capture = TIM_GetCapture3(TIM2);

TIM_SetCompare3(TIM2, capture + CCR3_Val);

}/* TIM2_CH4 toggling with frequency = 1464.8 Hz */

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

{

TIM_ClearITPendingBit(TIM2, TIM_IT_CC4);

capture = TIM_GetCapture4(TIM2);

TIM_SetCompare4(TIM2, capture + CCR4_Val);

}}
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一个定时器一个通道，产生不同频率
其它的设置都一样，就是在主函数中修改一个参数，然后在定时器中断中，根据这个参数，改变频率。

#include "stm32lib\\stm32f10x.h"

#include "hal.h"volatile u16 Key_Value=1000; //用于保存按键相应的PWM波占空比值

int main(void)

{

ChipHalInit();

ChipOutHalInit();while(1)

{

if( (!Get_Key_Up)&(!Get_Key_Down)&(!Get_Key_Left)&(!Get_Key_Right)&(!Get_Key_Ctrl) )

{

Key_Value=12000;

}

else

{

if(Get_Key_Up) //按键前进按下 ,对应1kHz

{

Key_Value=6000;

}

else if(Get_Key_Down) //按键后退按下 ,对应2kHz

{

Key_Value=3000;

}

Delay_Ms(20); //10ms延时if(Get_Key_Left) //按键左转按下,对应3kHz

{

Key_Value=2000;

}

else if(Get_Key_Right) //按键右转按下,对应4kHz

{

Key_Value=1500;

}

Delay_Ms(20); //10ms延时if(Get_Key_Ctrl) //按键控制按下,对应5kHz

{

Key_Value=1200;

}

Delay_Ms(20); //10ms延时

}

}

}extern volatile u16 Key_Value;

u16 capture=0;

void TIM3_IRQHandler(void)

{

/* TIM2_CH2 toggling with frequency = 366.2 Hz */

if (TIM_GetITStatus(TIM3, TIM_IT_CC2) != RESET)

{

TIM_ClearITPendingBit(TIM3, TIM_IT_CC2);

capture = TIM_GetCapture2(TIM3);

TIM_SetCompare2(TIM3, capture + Key_Value);

}

}void TIM3_Configuration(void)

{

TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;

TIM_OCInitTypeDef TIM_OCInitStructure;/* TIM2 clock enable */

RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);/*TIM1时钟配置*/

TIM_TimeBaseStructure.TIM_Prescaler = 5; //预分频(时钟分频)72M/6=12M

TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up; //向上计数

TIM_TimeBaseStructure.TIM_Period = 65535; //装载值选择最大

TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;

TIM_TimeBaseStructure.TIM_RepetitionCounter = 0x0;

TIM_TimeBaseInit(TIM3,&TIM_TimeBaseStructure);/* Channel 1 Configuration in PWM mode */

TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_Toggle; //PWM模式2

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

TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Disable;//反向通道无效

TIM_OCInitStructure.TIM_Pulse = Key_Value; //占空时间

TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_Low; //输出极性

TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High; //互补端的极性

TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;

TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;TIM_OC2Init(TIM3,&TIM_OCInitStructure); //通道2

TIM_OC2PreloadConfig(TIM3, TIM_OCPreload_Disable);

/* TIM1 counter enable */

TIM_Cmd(TIM3,ENABLE);

/* TIM1 Main Output Enable */

//TIM_CtrlPWMOutputs(TIM1,ENABLE);

TIM_ITConfig(TIM3, TIM_IT_CC2 , ENABLE);

}
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注意：在计算PWM频率的时候，TIMx的时钟都是72Mhz，分频后，因为翻转两次才能形成一个PWM波，因为，PWM的频率是捕获改变频率的1/2。

Answer 2

STM32的定时器就可以产生PWM。定时器框图有这几部分：时基（base），输入捕获（ic），输出比较（oc），以及比较捕获寄存器（ccr）。
时基部分主要是选择定时器的时钟源，分频系数等等。输入捕获是出理输入到芯片的信号的。捕获比较寄存器是各个功能所需要的寄存器。最后，输出比较功能可以输出PWM波。
PWM功能很常用，所以一般的芯片手册、HAL库都把PWM直接摘出来作为定时器的一部分。
原理是：设置一个加法计数器，比如0加到arr这个值。然后你设置一个比较值compare，这个值在0-arr之间。当加法计数器的值大于compare时，定时器输出通道的输出电平翻转。一直重复这个过程，就形成了PWM波。
显然，PWM波的周期由arr决定，占空比由compare决定。具体是怎么操作的，可以看芯片手册，还有HAL库函数。