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STM32 TIM 多通道互补PWM波形输出配置快速入门

platform：stm32f10xxx

lib：STM32F10x_StdPeriph_Lib_V3.5.0

前言

在做三相逆变的时候，需要软件生成SVPWM波形，具体的算法需要产生三对互补的PWM，这样可以驱动六个开关元件，stm32f103中的TIM1高级定时器支持产生三路互补PWM波形，下面进一步学习。

PWM产生的原理

TIM1的OC模块，可以产生PWM波形，具体步骤；

  • 寄存器TIMx CNT每过一个时钟周期就会加1；
  • 然后TIMx CNT的值与TIMx CCER进行比较；
  • 最终改变OC上的有效电平；

    以上只需要配置好TIM1的寄存器即可，无需再编程干预，当然可以动态修改TIMx CCER的值，从而改变占空比。可以参考下图；

    STM32 TIM 多通道互补PWM波形输出配置快速入门-LMLPHP

PWM模式

这里主要对PWM模式进行配置的时候做一下区分，存在以下两种情况；

  • TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
  • TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;

那么TIM_OCMode_PWM1和TIM_OCMode_PWM2有什么区别呢？

  • TIM_OCMode_PWM1PWM模式1

    在向上计数时，一旦TIMx_CNT<TIMx_CCR1时通道1为有效电平，否则为无效电平

    在向下计数时，一旦TIMx_CNT>TIMx_CCR1时通道1为无效电平(OC1REF=0)，否则为有效 电平(OC1REF=1)。
  • TIM_OCMode_PWM2 PWM模式2

    在向上计数时，一旦TIMx_CNT<TIMx_CCR1时通道1为无效电平，否则为有效电平

    在向下计数时，一旦TIMx_CNT>TIMx_CCR1时通道1为有效电平，否则为无效电平。

死区插入和刹车功能

互补PWM还支持插入死区时间，最主要的寄存器是TIMx_BDTR，在标准库中把相关的变量封装到TIM_BDTRInitTypeDef结构体中；具体如下；

typedef struct

{

  uint16_t TIM_OSSRState;        /*!< Specifies the Off-State selection used in Run mode.

                                      This parameter can be a value of @ref OSSR_Off_State_Selection_for_Run_mode_state */

  uint16_t TIM_OSSIState;        /*!< Specifies the Off-State used in Idle state.

                                      This parameter can be a value of @ref OSSI_Off_State_Selection_for_Idle_mode_state */

  uint16_t TIM_LOCKLevel;        /*!< Specifies the LOCK level parameters.

                                      This parameter can be a value of @ref Lock_level */

  uint16_t TIM_DeadTime;         /*!< Specifies the delay time between the switching-off and the

                                      switching-on of the outputs.

                                      This parameter can be a number between 0x00 and 0xFF  */

  uint16_t TIM_Break;            /*!< Specifies whether the TIM Break input is enabled or not.

                                      This parameter can be a value of @ref Break_Input_enable_disable */

  uint16_t TIM_BreakPolarity;    /*!< Specifies the TIM Break Input pin polarity.

                                      This parameter can be a value of @ref Break_Polarity */

  uint16_t TIM_AutomaticOutput;  /*!< Specifies whether the TIM Automatic Output feature is enabled or not.

                                      This parameter can be a value of @ref TIM_AOE_Bit_Set_Reset */

} TIM_BDTRInitTypeDef;

相关的含义看注释可以知道大概意思；这里整理了几个比较重要的变量；

  • 死区时间TIM_DeadTime的计算；TIMx_BDTR的低八位的配置决定了死区的时间；

    UTG[7:0]: 死区发生器设置 (Dead-time generator setup)

    这些位定义了插入互补输出之间的死区持续时间。假设DT表示其持续时间：
DTG[7:5]=0xx => DT=DTG[7:0] × TdtgTdtg = TDTS；
DTG[7:5]=10x => DT=(64+DTG[5:0]) × TdtgTdtg = 2 × TDTS；
DTG[7:5]=110 => DT=(32+DTG[4:0]) × TdtgTdtg = 8 × TDTS；
DTG[7:5]=111 => DT=(32+DTG[4:0])× TdtgTdtg = 16 × TDTS；

例：若TDTS = 125ns(8MHZ)，可能的死区时间为：

0到15875ns，若步长时间为125ns；

16us到31750ns，若步长时间为250ns；

32us到63us，若步长时间为1us；

64us到126us，若步长时间为2us；

注：一旦LOCK级别(TIMx_BDTR寄存器中的LOCK位)设为1、 2或3，则不能修改这些位。

  • TIM_Break 则表示是否决定使用刹车，如果发生错误，则可以通过刹车，第一时间停止PWM波形的产生，从而保证了系统的安全性；

代码实现

#include "stm32f10x.h"

#include "svpwm_driver.h"

#include "stm32f10x_tim.h"

#include "stm32f10x_it.h"

#include <stdio.h>

#define SVPWM_USE_BDT 	1

#define USE_HARD_PWM 	1

/**

  * @brief  Configures the different system clocks.

  * @param  None

  * @retval None

  */

void pwm_rcc_init(void)

{

  /* TIM1, GPIOA, GPIOB, GPIOE and AFIO clocks enable */

  RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1 | RCC_APB2Periph_GPIOA |

                         RCC_APB2Periph_AFIO |

                         RCC_APB2Periph_GPIOB, ENABLE);

}

void pwm_cnt_irq_init(void)

{

}

/**

  * @brief  Configure the TIM1 Pins.

  * @param  None

  * @retval None

  * @note

  *			PA8 /T1_CH1  ---> HIn3

  *			PA9 /T1_CH2  ---> HIn2

  *			PA10/T1_CH3  ---> HIn1

  *										Out2 ---> PA0/ADC0

  *										Out3 ---> PA1/ADC1

  *			PB15/T1_CHN3 ---> LIn1

  *			PB14/T1_CHN2 ---> LIn2

  *			PB13/T1_CHN1 ---> LIn3

  */

void pwm_pin_init(void)

{

	GPIO_InitTypeDef GPIO_InitStructure;

	/* GPIOA Configuration: Channel 1, 2 and 3 as alternate function push-pull */

	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_9 | GPIO_Pin_10 ;

	GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;

	GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;

	GPIO_Init(GPIOA, &GPIO_InitStructure);

	/* GPIOB Configuration: Channel 1N, 2N and 3N as alternate function push-pull */

	GPIO_InitStructure.GPIO_Pin = GPIO_Pin_13 | GPIO_Pin_14 | GPIO_Pin_15;

	GPIO_Init(GPIOB, &GPIO_InitStructure);

}

void pwm_tim_init(void){

	TIM_TimeBaseInitTypeDef  TIM_TimeBaseStructure;

	TIM_OCInitTypeDef  TIM_OCInitStructure;

	TIM_BDTRInitTypeDef      TIM_BDTRInitStructure;

//	NVIC_InitTypeDef 	NVIC_InitStructure;

	uint16_t TimerPeriod = 0;

	uint16_t Channel1Pulse = 0, Channel2Pulse = 0, Channel3Pulse = 0;

	/* TIM1 Configuration ---------------------------------------------------

	 Generate 7 PWM signals with 4 different duty cycles:

	 TIM1CLK = SystemCoreClock, Prescaler = 0, TIM1 counter clock = SystemCoreClock

	 SystemCoreClock is set to 72 MHz for Low-density, Medium-density, High-density

	 and Connectivity line devices and to 24 MHz for Low-Density Value line and

	 Medium-Density Value line devices

	 The objective is to generate 7 PWM signal at 17.57 KHz:

	   - TIM1_Period = (SystemCoreClock / 17570) - 1

	 The channel 1 and channel 1N duty cycle is set to 50%

	 The channel 2 and channel 2N duty cycle is set to 50%

	 The channel 3 and channel 3N duty cycle is set to 50%

	 The Timer pulse is calculated as follows:

	   - ChannelxPulse = DutyCycle * (TIM1_Period - 1) / 100

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

	TimerPeriod = (SYS_FRQ / PWM_FRQ ) - 1;

	/* Compute CCR1 value to generate a duty cycle at 50% for channel 1 and 1N */

	Channel1Pulse = (uint16_t) (((uint32_t) PWM_DUTY * (TimerPeriod - 1)) / 100);

	/* Compute CCR2 value to generate a duty cycle at 37.5%  for channel 2 and 2N */

	Channel2Pulse = (uint16_t) (((uint32_t) PWM_DUTY * (TimerPeriod - 1)) / 100);

	/* Compute CCR3 value to generate a duty cycle at 25%  for channel 3 and 3N */

	Channel3Pulse = (uint16_t) (((uint32_t) PWM_DUTY * (TimerPeriod - 1)) / 100);

	//TIM_DeInit(TIM1);

	/* Time Base configuration */

	TIM_TimeBaseStructure.TIM_Prescaler = TIM_PSCReloadMode_Update;

	//TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;//

	TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_CenterAligned2;

	TIM_TimeBaseStructure.TIM_Period = TimerPeriod;

	TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;

	TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;

	TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);

	/*

	TIM_ClearFlag(TIM1, TIM_FLAG_Update);

	TIM_ITConfig(TIM1,TIM_IT_Update, ENABLE);

	NVIC_InitStructure.NVIC_IRQChannel = TIM1_UP_IRQn;

	NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0x00;

	NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0x02;

	NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;

	NVIC_Init(&NVIC_InitStructure);

	*/

	/* Channel 1, 2, 3 Configuration in PWM mode */

	#if USE_HARD_PWM

	/**

	TIM_OCMode_PWM1	PWM模式1

	在向上计数时，一旦TIMx_CNT<TIMx_CCR1时通道1为有效电平，否则为无效电平

	在向下计数时，一旦TIMx_CNT>TIMx_CCR1时通道1为无效电平(OC1REF=0)，否则为有效 电平(OC1REF=1)。

	TIM_OCMode_PWM2 PWM模式2

	在向上计数时，一旦TIMx_CNT<TIMx_CCR1时通道1为无效电平，否则为有效电平

	在向下计数时，一旦TIMx_CNT>TIMx_CCR1时通道1为有效电平，否则为无效电平。

	*/

	TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;

	TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;

	TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;

	TIM_OCInitStructure.TIM_Pulse = Channel1Pulse;

	TIM_OCInitStructure.TIM_OCPolarity = TIM_OCPolarity_High;

	TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCPolarity_High;

	TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Reset;

	TIM_OCInitStructure.TIM_OCNIdleState = TIM_OCIdleState_Reset;

	TIM_OC1Init(TIM1, &TIM_OCInitStructure);

	TIM_OCInitStructure.TIM_Pulse = Channel2Pulse;

	TIM_OC2Init(TIM1, &TIM_OCInitStructure);

	TIM_OCInitStructure.TIM_Pulse = Channel3Pulse;

	TIM_OC3Init(TIM1, &TIM_OCInitStructure);

	TIM_OC1PreloadConfig(TIM1,TIM_OCPreload_Enable);

	TIM_OC2PreloadConfig(TIM1,TIM_OCPreload_Enable);

	TIM_OC3PreloadConfig(TIM1,TIM_OCPreload_Enable);

	#endif

#if SVPWM_USE_BDT

	TIM_BDTRInitStructure.TIM_OSSRState = TIM_OSSRState_Enable;

	TIM_BDTRInitStructure.TIM_OSSIState = TIM_OSSIState_Enable;

	TIM_BDTRInitStructure.TIM_LOCKLevel = TIM_LOCKLevel_OFF;

	TIM_BDTRInitStructure.TIM_DeadTime = 30;

	TIM_BDTRInitStructure.TIM_Break = TIM_Break_Disable;

	TIM_BDTRInitStructure.TIM_BreakPolarity = TIM_BreakPolarity_Low;

	TIM_BDTRInitStructure.TIM_AutomaticOutput = TIM_AutomaticOutput_Disable;

	TIM_BDTRConfig(TIM1, &TIM_BDTRInitStructure);

#endif

	TIM_CCPreloadControl(TIM1,ENABLE);

	/* TIM1 counter enable */

	TIM_Cmd(TIM1, ENABLE);

	/* TIM1 Main Output Enable */

	TIM_CtrlPWMOutputs(TIM1, ENABLE);

}

void pwm_init(void){

	pwm_rcc_init();

	pwm_pin_init();

	pwm_cnt_irq_init();

	pwm_tim_init();

}

int32_t get_pwm_period(void){

	return (int32_t)((SYS_FRQ / PWM_FRQ ) - 1);

}

void pwm_reset_duty_cnt(uint8_t index, int16_t cnt){

	if(cnt <= 0){

		cnt = get_pwm_period()/2;

	}

	switch(index){

		case 1:

			TIM1->CCR1 = (uint16_t)cnt;

		break;

		case 2:

			TIM1->CCR2 = (uint16_t)cnt;

		break;

		case 3:

			TIM1->CCR3 = (uint16_t)cnt;

		break;

	}

}

void pwm_disable(void){

	TIM_CtrlPWMOutputs(TIM1, DISABLE);

}

void pwm_enable(void){

	TIM_CtrlPWMOutputs(TIM1, ENABLE);

}

以上代码主要实现以下几个功能；

  • IM1定时器时钟，使用中央对齐模式1，则会产生上溢信号；
  • PWM模式设置为TIM_OCMode_PWM1；
  • 加入了死区；
  • 占空比 50%；

    具体如下图所示；

    STM32 TIM 多通道互补PWM波形输出配置快速入门-LMLPHP

    STM32 TIM 多通道互补PWM波形输出配置快速入门-LMLPHP

参考

http://www.stmcu.org.cn/module/forum/thread-613602-1-1.html

05-02 10:49
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