如何用stm32f407控制pwm輸出增加減小占空比
uj5u.com熱心網友回復：
如果你使用的是STM32F4xx_StdPeriph_Driver，你可以找的里面有個PWM的例子。/**
******************************************************************************
* @file TIM/TIM_7PWMOutput/main.c
* @author MCD Application Team
* @version V1.8.0
* @date 04-November-2016
* @brief Main program body
******************************************************************************
* @attention
*
* <h2><center>© COPYRIGHT 2016 STMicroelectronics</center></h2>
*
* Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
* You may not use this file except in compliance with the License.
* You may obtain a copy of the License at:
*
* http://www.st.com/software_license_agreement_liberty_v2
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
******************************************************************************
*/
/* Includes ------------------------------------------------------------------*/
#include "stm32f4xx.h"
/** @addtogroup STM32F4xx_StdPeriph_Examples
* @{
*/
/** @addtogroup TIM_7PWM_Output
* @{
*/
/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
uint16_t TimerPeriod = 0;
uint16_t Channel1Pulse = 0, Channel2Pulse = 0, Channel3Pulse = 0, Channel4Pulse = 0;
/* Private function prototypes -----------------------------------------------*/
void TIM_Config(void);
/* Private functions ---------------------------------------------------------*/
/**
* @brief Main program
* @param None
* @retval None
*/
int main(void)
{
/*!< At this stage the microcontroller clock setting is already configured,
this is done through SystemInit() function which is called from startup
files (startup_stm32f40_41xxx.s/startup_stm32f427_437xx.s/startup_stm32f429_439xx.s)
before to branch to application main.
To reconfigure the default setting of SystemInit() function, refer to
system_stm32f4xx.c file
*/
/* TIM Configuration */
TIM_Config();
/* TIM1 Configuration ---------------------------------------------------
Generate 7 PWM signals with 4 different duty cycles:
TIM1 input clock (TIM1CLK) is set to 2 * APB2 clock (PCLK2), since APB2
prescaler is different from 1.
TIM1CLK = 2 * PCLK2
PCLK2 = HCLK / 2
=> TIM1CLK = 2 * (HCLK / 2) = HCLK = SystemCoreClock
TIM1CLK = SystemCoreClock, Prescaler = 0, TIM1 counter clock = SystemCoreClock
SystemCoreClock is set to 168 MHz for STM32F4xx 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 37.5%
The channel 3 and channel 3N duty cycle is set to 25%
The channel 4 duty cycle is set to 12.5%
The Timer pulse is calculated as follows:
- ChannelxPulse = DutyCycle * (TIM1_Period - 1) / 100
Note:
SystemCoreClock variable holds HCLK frequency and is defined in system_stm32f4xx.c file.
Each time the core clock (HCLK) changes, user had to call SystemCoreClockUpdate()
function to update SystemCoreClock variable value. Otherwise, any configuration
based on this variable will be incorrect.
----------------------------------------------------------------------- */
/* Compute the value to be set in ARR register to generate signal frequency at 17.57 Khz */
TimerPeriod = (SystemCoreClock / 17570 ) - 1;
/* Compute CCR1 value to generate a duty cycle at 50% for channel 1 and 1N */
Channel1Pulse = (uint16_t) (((uint32_t) 5 * (TimerPeriod - 1)) / 10);
/* Compute CCR2 value to generate a duty cycle at 37.5% for channel 2 and 2N */
Channel2Pulse = (uint16_t) (((uint32_t) 375 * (TimerPeriod - 1)) / 1000);
/* Compute CCR3 value to generate a duty cycle at 25% for channel 3 and 3N */
Channel3Pulse = (uint16_t) (((uint32_t) 25 * (TimerPeriod - 1)) / 100);
/* Compute CCR4 value to generate a duty cycle at 12.5% for channel 4 */
Channel4Pulse = (uint16_t) (((uint32_t) 125 * (TimerPeriod- 1)) / 1000);
/* TIM1 clock enable */
RCC_APB2PeriphClockCmd(RCC_APB2Periph_TIM1 , ENABLE);
/* Time Base configuration */
TIM_TimeBaseStructure.TIM_Prescaler = 0;
TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
TIM_TimeBaseStructure.TIM_Period = TimerPeriod;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
TIM_TimeBaseInit(TIM1, &TIM_TimeBaseStructure);
/* Channel 1, 2,3 and 4 Configuration in PWM mode */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM2;
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_Low;
TIM_OCInitStructure.TIM_OCNPolarity = TIM_OCNPolarity_High;
TIM_OCInitStructure.TIM_OCIdleState = TIM_OCIdleState_Set;
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_OCInitStructure.TIM_Pulse = Channel4Pulse;
TIM_OC4Init(TIM1, &TIM_OCInitStructure);
/* TIM1 counter enable */
TIM_Cmd(TIM1, ENABLE);
/* TIM1 Main Output Enable */
TIM_CtrlPWMOutputs(TIM1, ENABLE);
while (1)
{}
}
/**
* @brief Configure the TIM1 Pins.
* @param None
* @retval None
*/
void TIM_Config(void)
{
GPIO_InitTypeDef GPIO_InitStructure;
/* GPIOA, GPIOB and GPIOE Clocks enable */
RCC_AHB1PeriphClockCmd( RCC_AHB1Periph_GPIOA | RCC_AHB1Periph_GPIOB | RCC_AHB1Periph_GPIOE , ENABLE);
/* GPIOA Configuration: Channel 1 and 3 as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_8 | GPIO_Pin_10;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_100MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource8, GPIO_AF_TIM1);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource10, GPIO_AF_TIM1);
/* GPIOE Configuration: Channel 2 and 4 as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11 | GPIO_Pin_14;
GPIO_Init(GPIOE, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOE, GPIO_PinSource11, GPIO_AF_TIM1);
GPIO_PinAFConfig(GPIOE, GPIO_PinSource14, GPIO_AF_TIM1);
/* 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);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource13, GPIO_AF_TIM1);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource14, GPIO_AF_TIM1);
GPIO_PinAFConfig(GPIOB, GPIO_PinSource15, GPIO_AF_TIM1);
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t* file, uint32_t line)
{
/* User can add his own implementation to report the file name and line number,
ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
while (1)
{}
}
#endif
/**
* @}
*/
/**
* @}
*/
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
72-88描述了是如何計算占比
96-105是具體的設定。
你可以根據你自己硬體的時鐘需要，更改引數。
uj5u.com熱心網友回復：
你設定TIM的CCRxARR暫存器就可以動態修改定時器占空比。了前者修改電平變化的周后者或者改變定時器計時數
uj5u.com熱心網友回復：
一樓，用函式庫太啰嗦了，玩stm32要用暫存器才爽。二樓兄弟是老手。
PWM 操作暫存器比用庫簡單清晰N倍，
PSC: 控制每個脈沖時長
ARR: 頻率，即多少個脈沖為一周期
CCR: 占空比，即高電平用多少個脈沖
CCMR: 選擇PWM方式
CCER: 使能指定通道
CR: 使能TIM
搞掂。。
用暫存器寫，GPIO、時鐘、PWM，二十行代碼都不用！
uj5u.com熱心網友回復：
改變CCR暫存器的值就成，就一行代碼，如:TIM1->CCR1= 45；
問這個問題，其實證明你還不了解TIM部分，這部分我看了不下五遍才有個大概門路。
加油~
轉載請註明出處，本文鏈接：https://www.uj5u.com/qita/108509.html
標籤：單片機/工控