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在使用STM32G431RBT6实现等精度测量频率法的时候发现测量出来的误差很大很大。我是采用的TIM2的CH2输出一个频率可调的PWM波，然后用TIM3的CH2作输入捕获来测量频率，我在网上学习了一下关于等精度测量法的知识，然后发现自己用代码实现的时候总出错，希望有大佬帮我指出问题！
（PS：这块板子的系统频率是80MHz）
下面附上我基于HAL库的代码，主函数中的ADD函数是我输出PWM波可调的函数，ADD中的输入变量即是最后输出的频率值，已经用示波器测过了，误差不超过1hz。我我发现当我输入一个实际频率为1000Hz的时候，测量值显示为5532.5Hz +-0.5跳变。
main.c
tim.c:
#include "tim.h"
/* USER CODE BEGIN 0 */
/* USER CODE END 0 */
TIM_HandleTypeDef htim2;
TIM_HandleTypeDef htim3;
TIM_HandleTypeDef htim4;
/* TIM2 init function */
void MX_TIM2_Init(void)
{
/* USER CODE BEGIN TIM2_Init 0 */
/* USER CODE END TIM2_Init 0 */
TIM_MasterConfigTypeDef sMasterConfig = {0};
TIM_OC_InitTypeDef sConfigOC = {0};
/* USER CODE BEGIN TIM2_Init 1 */
/* USER CODE END TIM2_Init 1 */
htim2.Instance = TIM2;
htim2.Init.Prescaler = 500-1;
htim2.Init.CounterMode = TIM_COUNTERMODE_UP;
htim2.Init.Period = 399;
htim2.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim2.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
if (HAL_TIM_PWM_Init(&htim2) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim2, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
sConfigOC.OCMode = TIM_OCMODE_PWM1;
sConfigOC.Pulse = 0;
sConfigOC.OCPolarity = TIM_OCPOLARITY_HIGH;
sConfigOC.OCFastMode = TIM_OCFAST_DISABLE;
if (HAL_TIM_PWM_ConfigChannel(&htim2, &sConfigOC, TIM_CHANNEL_2) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN TIM2_Init 2 */
/* USER CODE END TIM2_Init 2 */
HAL_TIM_MspPostInit(&htim2);
}
/* TIM3 init function */
void MX_TIM3_Init(void)
{
/* USER CODE BEGIN TIM3_Init 0 */
/* USER CODE END TIM3_Init 0 */
TIM_ClockConfigTypeDef sClockSourceConfig = {0};
TIM_MasterConfigTypeDef sMasterConfig = {0};
TIM_IC_InitTypeDef sConfigIC = {0};
/* USER CODE BEGIN TIM3_Init 1 */
__HAL_RCC_TIM3_CLK_ENABLE();
/* USER CODE END TIM3_Init 1 */
htim3.Instance = TIM3;
htim3.Init.Prescaler = 0;
htim3.Init.CounterMode = TIM_COUNTERMODE_UP;
htim3.Init.Period = 65535;
htim3.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim3.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_ENABLE;
if (HAL_TIM_Base_Init(&htim3) != HAL_OK)
{
Error_Handler();
}
sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
if (HAL_TIM_ConfigClockSource(&htim3, &sClockSourceConfig) != HAL_OK)
{
Error_Handler();
}
if (HAL_TIM_IC_Init(&htim3) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim3, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
sConfigIC.ICPolarity = TIM_INPUTCHANNELPOLARITY_RISING;
sConfigIC.ICSelection = TIM_ICSELECTION_DIRECTTI;
sConfigIC.ICPrescaler = TIM_ICPSC_DIV1;
sConfigIC.ICFilter = 0;
if (HAL_TIM_IC_ConfigChannel(&htim3, &sConfigIC, TIM_CHANNEL_2) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN TIM3_Init 2 */
HAL_TIM_IC_Start_IT(&htim3, TIM_CHANNEL_2);
/* USER CODE END TIM3_Init 2 */
}
/* TIM4 init function */
void MX_TIM4_Init(void)
{
/* USER CODE BEGIN TIM4_Init 0 */
__HAL_RCC_TIM4_CLK_ENABLE();
/* USER CODE END TIM4_Init 0 */
TIM_ClockConfigTypeDef sClockSourceConfig = {0};
TIM_MasterConfigTypeDef sMasterConfig = {0};
/* USER CODE BEGIN TIM4_Init 1 */
/* USER CODE END TIM4_Init 1 */
htim4.Instance = TIM4;
htim4.Init.Prescaler = 0;
htim4.Init.CounterMode = TIM_COUNTERMODE_UP;
htim4.Init.Period = 65535;
htim4.Init.ClockDivision = TIM_CLOCKDIVISION_DIV1;
htim4.Init.AutoReloadPreload = TIM_AUTORELOAD_PRELOAD_DISABLE;
if (HAL_TIM_Base_Init(&htim4) != HAL_OK)
{
Error_Handler();
}
sClockSourceConfig.ClockSource = TIM_CLOCKSOURCE_INTERNAL;
if (HAL_TIM_ConfigClockSource(&htim4, &sClockSourceConfig) != HAL_OK)
{
Error_Handler();
}
sMasterConfig.MasterOutputTrigger = TIM_TRGO_RESET;
sMasterConfig.MasterSlaveMode = TIM_MASTERSLAVEMODE_DISABLE;
if (HAL_TIMEx_MasterConfigSynchronization(&htim4, &sMasterConfig) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN TIM4_Init 2 */
HAL_TIM_Base_Start_IT(&htim4);
/* USER CODE END TIM4_Init 2 */
}
void HAL_TIM_PWM_MspInit(TIM_HandleTypeDef* tim_pwmHandle)
{
if(tim_pwmHandle->Instance==TIM2)
{
/* USER CODE BEGIN TIM2_MspInit 0 */
/* USER CODE END TIM2_MspInit 0 */
/* TIM2 clock enable */
__HAL_RCC_TIM2_CLK_ENABLE();
/* USER CODE BEGIN TIM2_MspInit 1 */
/* USER CODE END TIM2_MspInit 1 */
}
}
void HAL_TIM_Base_MspInit(TIM_HandleTypeDef* tim_baseHandle)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
if(tim_baseHandle->Instance==TIM3)
{
/* USER CODE BEGIN TIM3_MspInit 0 */
/* USER CODE END TIM3_MspInit 0 */
/* TIM3 clock enable */
__HAL_RCC_TIM3_CLK_ENABLE();
__HAL_RCC_GPIOA_CLK_ENABLE();
/**TIM3 GPIO Configuration
PA4 ------> TIM3_CH2
*/
GPIO_InitStruct.Pin = GPIO_PIN_4;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF2_TIM3;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/* TIM3 interrupt Init */
HAL_NVIC_SetPriority(TIM3_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(TIM3_IRQn);
/* USER CODE BEGIN TIM3_MspInit 1 */
/* USER CODE END TIM3_MspInit 1 */
}
else if(tim_baseHandle->Instance==TIM4)
{
/* USER CODE BEGIN TIM4_MspInit 0 */
/* USER CODE END TIM4_MspInit 0 */
/* TIM4 clock enable */
__HAL_RCC_TIM4_CLK_ENABLE();
/* TIM4 interrupt Init */
HAL_NVIC_SetPriority(TIM4_IRQn, 0, 0);
HAL_NVIC_EnableIRQ(TIM4_IRQn);
/* USER CODE BEGIN TIM4_MspInit 1 */
/* USER CODE END TIM4_MspInit 1 */
}
}
void HAL_TIM_MspPostInit(TIM_HandleTypeDef* timHandle)
{
GPIO_InitTypeDef GPIO_InitStruct = {0};
if(timHandle->Instance==TIM2)
{
/* USER CODE BEGIN TIM2_MspPostInit 0 */
/* USER CODE END TIM2_MspPostInit 0 */
__HAL_RCC_GPIOA_CLK_ENABLE();
/**TIM2 GPIO Configuration
PA1 ------> TIM2_CH2
*/
GPIO_InitStruct.Pin = GPIO_PIN_1;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
GPIO_InitStruct.Alternate = GPIO_AF1_TIM2;
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/* USER CODE BEGIN TIM2_MspPostInit 1 */
/* USER CODE END TIM2_MspPostInit 1 */
}
}
void HAL_TIM_PWM_MspDeInit(TIM_HandleTypeDef* tim_pwmHandle)
{
if(tim_pwmHandle->Instance==TIM2)
{
/* USER CODE BEGIN TIM2_MspDeInit 0 */
/* USER CODE END TIM2_MspDeInit 0 */
/* Peripheral clock disable */
__HAL_RCC_TIM2_CLK_DISABLE();
/* USER CODE BEGIN TIM2_MspDeInit 1 */
/* USER CODE END TIM2_MspDeInit 1 */
}
}
void HAL_TIM_Base_MspDeInit(TIM_HandleTypeDef* tim_baseHandle)
{
if(tim_baseHandle->Instance==TIM3)
{
/* USER CODE BEGIN TIM3_MspDeInit 0 */
/* USER CODE END TIM3_MspDeInit 0 */
/* Peripheral clock disable */
__HAL_RCC_TIM3_CLK_DISABLE();
/**TIM3 GPIO Configuration
PA4 ------> TIM3_CH2
*/
HAL_GPIO_DeInit(GPIOA, GPIO_PIN_4);
/* TIM3 interrupt Deinit */
HAL_NVIC_DisableIRQ(TIM3_IRQn);
/* USER CODE BEGIN TIM3_MspDeInit 1 */
/* USER CODE END TIM3_MspDeInit 1 */
}
else if(tim_baseHandle->Instance==TIM4)
{
/* USER CODE BEGIN TIM4_MspDeInit 0 */
HAL_NVIC_SetPriority(TIM4_IRQn, 0, 1);
HAL_NVIC_EnableIRQ(TIM4_IRQn);
/* USER CODE END TIM4_MspDeInit 0 */
/* Peripheral clock disable */
__HAL_RCC_TIM4_CLK_DISABLE();
/* TIM4 interrupt Deinit */
HAL_NVIC_DisableIRQ(TIM4_IRQn);
/* USER CODE BEGIN TIM4_MspDeInit 1 */
/* USER CODE END TIM4_MspDeInit 1 */
}
}
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
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