mirror of
https://github.com/STMicroelectronics/STM32CubeF4.git
synced 2025-05-11 19:29:45 +08:00
89 lines
3.6 KiB
Plaintext
89 lines
3.6 KiB
Plaintext
/**
|
|
@page TIM_InputCapture TIM Input Capture example
|
|
|
|
@verbatim
|
|
******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
|
|
* @file TIM/TIM_InputCapture/readme.txt
|
|
* @author MCD Application Team
|
|
* @brief Description of the TIM Input Capture example.
|
|
******************************************************************************
|
|
* @attention
|
|
*
|
|
* Copyright (c) 2017 STMicroelectronics.
|
|
* All rights reserved.
|
|
*
|
|
* This software is licensed under terms that can be found in the LICENSE file
|
|
* in the root directory of this software component.
|
|
* If no LICENSE file comes with this software, it is provided AS-IS.
|
|
*
|
|
******************************************************************************
|
|
@endverbatim
|
|
|
|
@par Example Description
|
|
|
|
This example shows how to use the TIM peripheral to measure the frequency of
|
|
an external signal.
|
|
|
|
The TIM1CLK frequency is set to SystemCoreClock /2 (Hz), the Prescaler is 0,
|
|
so the TIM1 counter clock is SystemCoreClock (Hz)/2.
|
|
SystemCoreClock is set to 168 MHz for STM32F4xx Devices.
|
|
|
|
TIM1 is configured in Input Capture Mode: the external signal is connected to
|
|
TIM1 Channel2 used as input pin.
|
|
To measure the frequency we use the TIM1 CC2 interrupt request, so in the
|
|
TIM1_CC_IRQHandler routine, the frequency of the external signal is computed.
|
|
|
|
The "uwFrequency" variable contains the external signal frequency:
|
|
uwFrequency = TIM1 counter clock / uwDiffCapture (Hz),
|
|
where "uwDiffCapture" is the difference between two consecutive TIM1 captures.
|
|
|
|
|
|
The minimum frequency value to measure is 2x (TIM1 counter clock / CCR MAX)
|
|
= 2x(168MHz/2)/ 65535
|
|
= 2564 Hz
|
|
|
|
@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
|
|
based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
|
|
a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
|
|
than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
|
|
To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
|
|
|
|
@note The application needs to ensure that the SysTick time base is always set to 1 millisecond
|
|
to have correct HAL operation.
|
|
|
|
@par Keywords
|
|
|
|
Timers, DMA, Frequency, Input, Capture, External Signal, Measurement
|
|
|
|
@par Directory contents
|
|
|
|
- TIM/TIM_InputCapture/Inc/stm32f4xx_hal_conf.h HAL configuration file
|
|
- TIM/TIM_InputCapture/Inc/stm32f4xx_it.h Interrupt handlers header file
|
|
- TIM/TIM_InputCapture/Inc/main.h Main program header file
|
|
- TIM/TIM_InputCapture/Src/stm32f4xx_it.c Interrupt handlers
|
|
- TIM/TIM_InputCapture/Src/main.c Main program
|
|
- TIM/TIM_InputCapture/Src/stm32f4xx_hal_msp.c HAL MSP module
|
|
- TIM/TIM_InputCapture/Src/system_stm32f4xx.c STM32F4xx system clock configuration file
|
|
|
|
|
|
@par Hardware and Software environment
|
|
|
|
- This example runs on STM32F407xx/417xx devices.
|
|
|
|
- This example has been tested with STMicroelectronics STM324xG-EVAL RevC
|
|
evaluation boards and can be easily tailored to any other supported device and development board
|
|
|
|
- STM324xG-EVAL RevC Set-up
|
|
- Connect the external signal to measure to the TIM1 CH2 pin (PE.11).
|
|
|
|
|
|
@par How to use it ?
|
|
|
|
In order to make the program work, you must do the following :
|
|
- Open your preferred toolchain
|
|
- Rebuild all files and load your image into target memory
|
|
- Run the example
|
|
|
|
|
|
*/
|