本帖最后由 jmworkspace 于 2014-5-21 14:14 编辑
如上图为tim1输出口PA11输出的波形
如上图为实际信号发信器产生的波形
为什么两者不相同，实际测出来的波形有一小段弧形？这是什么原因造成的？
主函数代码如下：
/**
******************************************************************************
******************************************************************************
* @attention
*
* <h2><center>© COPYRIGHT 2012 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:
* *
* 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 "stm32f0xx.h"
/** @addtogroup STM32F0_Discovery_Peripheral_Examples
* @{
*/
/** @addtogroup TIM_PWM_Input
* @{
*/
/* Private typedef -----------------------------------------------------------*/
/* Private define ------------------------------------------------------------*/
/* Private macro -------------------------------------------------------------*/
/* Private variables ---------------------------------------------------------*/
TIM_ICInitTypeDef TIM_ICInitStructure;
TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
TIM_OCInitTypeDef TIM_OCInitStructure;
GPIO_InitTypeDef GPIO_InitStructure;
NVIC_InitTypeDef NVIC_InitStructure;
extern __IO uint32_t Frequency;
extern __IO uint16_t DutyCycle;
/* Private function prototypes -----------------------------------------------*/
void TIM_Config(void);
void Output_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
file (startup_stm32f0xx.s) before to branch to application main.
To reconfigure the default setting of SystemInit() function, refer to
system_stm32f0xx.c file
*/
/* TIM Configuration */
TIM_Config();
Output_TIM_Config();
/* ---------------------------------------------------------------------------
TIM2 configuration: PWM Input mode
In this example TIM2 input clock (TIM2CLK) is set to APB1 clock (PCLK1)
TIM2CLK = PCLK1
=> TIM2CLK = HCLK = SystemCoreClock
External Signal Frequency = TIM2 counter clock / TIM2_CCR2 in Hz.
External Signal DutyCycle = (TIM2_CCR1*100)/(TIM2_CCR2) in %.
--------------------------------------------------------------------------- */
TIM_ICInitStructure.TIM_Channel = TIM_Channel_2;
TIM_ICInitStructure.TIM_ICPolarity = TIM_ICPolarity_Rising;
TIM_ICInitStructure.TIM_ICSelection = TIM_ICSelection_DirectTI;
TIM_ICInitStructure.TIM_ICPrescaler = TIM_ICPSC_DIV1;
TIM_ICInitStructure.TIM_ICFilter = 0x0;
TIM_PWMIConfig(TIM2, &TIM_ICInitStructure);
/* Select the TIM2 Input Trigger: TI2FP2 */
TIM_SelectInputTrigger(TIM2, TIM_TS_TI2FP2);
/* Select the slave Mode: Reset Mode */
TIM_SelectSlaveMode(TIM2, TIM_SlaveMode_Reset);
TIM_SelectMasterSlaveMode(TIM2,TIM_MasterSlaveMode_Enable);
/* TIM enable counter */
TIM_Cmd(TIM2, ENABLE);
/* Enable the CC2 Interrupt Request */
TIM_ITConfig(TIM2, TIM_IT_CC2, ENABLE);
/* TIM enable counter */
TIM_Cmd(TIM1, ENABLE);
/* TIM1 Main Output Enable */
TIM_CtrlPWMOutputs(TIM3, ENABLE);
/* Infinite loop */
while (1)
{}
}
/**
* @brief Configure the TIM IRQ Handler.
* @param None
* @retval None
*/
void TIM_Config(void)
{
/* TIM2 clock enable */
RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);
/* GPIOA clock enable */
RCC_AHBPeriphClockCmd(RCC_AHBPeriph_GPIOA, ENABLE);
/* TIM2 chennel2 configuration : PA.01 */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_1;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
/* Connect TIM pin to AF2 */
GPIO_PinAFConfig(GPIOA, GPIO_PinSource1, GPIO_AF_2);
/* Enable the TIM2 global Interrupt */
NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
NVIC_InitStructure.NVIC_IRQChannelPriority = 0;
NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
NVIC_Init(&NVIC_InitStructure);
}
void Output_TIM_Config(void)
{
/* GPIOA Clocks enable */
RCC_AHBPeriphClockCmd( RCC_AHBPeriph_GPIOA, ENABLE);
/* GPIOA Configuration: Channel 1, 2, 3 and 4 as alternate function push-pull */
GPIO_InitStructure.GPIO_Pin = GPIO_Pin_11;
GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP ;
GPIO_Init(GPIOA, &GPIO_InitStructure);
GPIO_PinAFConfig(GPIOA, GPIO_PinSource11, GPIO_AF_2);
/* 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 = Frequency;
TIM_TimeBaseStructure.TIM_ClockDivision = 0;
TIM_TimeBaseStructure.TIM_RepetitionCounter = 0;
/* Channel 1, 2, 3 and 4 Configuration in PWM mode */
TIM_OCInitStructure.TIM_OCMode = TIM_OCMode_PWM1;
TIM_OCInitStructure.TIM_OutputState = TIM_OutputState_Enable;
TIM_OCInitStructure.TIM_OutputNState = TIM_OutputNState_Enable;
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_OCInitStructure.TIM_Pulse = DutyCycle;
TIM_OC1Init(TIM1, &TIM_OCInitStructure);
}
#ifdef USE_FULL_ASSERT
/**
*/
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) */
/* Infinite loop */
while (1)
{
}
}
#endif
/**
* @}
*/
/**
* @}
*/
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/
中断函数如下：
void TIM2_IRQHandler(void)
{
RCC_ClocksTypeDef RCC_Clocks;
RCC_GetClocksFreq(&RCC_Clocks);
/* Clear TIM2 Capture compare interrupt pending bit */
TIM_ClearITPendingBit(TIM2, TIM_IT_CC2);
/* Get the Input Capture value */
IC2Value = TIM_GetCapture2(TIM2);
if (IC2Value != 0)
{
/* Duty cycle computation */
DutyCycle = (TIM_GetCapture1(TIM2) * 100) / IC2Value;
/* Frequency computation
TIM2 counter clock = (RCC_Clocks.HCLK_Frequency)/2 */
Frequency = RCC_Clocks.HCLK_Frequency / IC2Value;
}
else
{
DutyCycle = 0;
Frequency = 0;
}
}
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