88 lines
3.7 KiB
Plaintext
88 lines
3.7 KiB
Plaintext
/**
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@page TIM_InputCapture Input Capture example
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@verbatim
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******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
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* @file TIM/TIM_InputCapture/readme.txt
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* @author MCD Application Team
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* @brief Description of the TIM_InputCapture example.
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******************************************************************************
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* @attention
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*
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* <h2><center>© Copyright (c) 2016 STMicroelectronics.
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* All rights reserved.</center></h2>
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*
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* This software component is licensed by ST under BSD 3-Clause license,
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* the "License"; You may not use this file except in compliance with the
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* License. You may obtain a copy of the License at:
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* opensource.org/licenses/BSD-3-Clause
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*
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******************************************************************************
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@endverbatim
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@par Example Description
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Use of the TIM peripheral to measure an external signal frequency.
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The TIM2CLK frequency is set to SystemCoreClock (Hz), the Prescaler is 0,
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so the TIM2 counter clock is SystemCoreClock (Hz).
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SystemCoreClock is set to 72 MHz for STM32F103xG Devices.
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TIM2 is configured in Input Capture Mode: the external signal is connected to
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TIM2 Channel2 used as input pin.
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To measure the frequency we use the TIM2 CC2 interrupt request, so in the
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TIM2_IRQHandler routine, the frequency of the external signal is computed.
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The "uwFrequency" variable contains the external signal frequency:
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uwFrequency = TIM2 counter clock / uwDiffCapture (Hz),
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where "uwDiffCapture" is the difference between two consecutive TIM2 captures.
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The minimum frequency value to measure is TIM2 counter clock / CCR MAX
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= 72 MHz / 65535
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Due to TIM2_IRQHandler processing time (around 3.50us), the maximum
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frequency value to measure is around 300kHz.
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@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
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based on variable incremented in SysTick ISR. This implies that if HAL_Delay() is called from
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a peripheral ISR process, then the SysTick interrupt must have higher priority (numerically lower)
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than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
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To change the SysTick interrupt priority you have to use HAL_NVIC_SetPriority() function.
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@note The application need to ensure that the SysTick time base is always set to 1 millisecond
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to have correct HAL operation.
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@par Directory contents
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- TIM/TIM_InputCapture/Inc/stm32f1xx_hal_conf.h HAL configuration file
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- TIM/TIM_InputCapture/Inc/stm32f1xx_it.h Interrupt handlers header file
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- TIM/TIM_InputCapture/Inc/main.h Header for main.c module
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- TIM/TIM_InputCapture/Src/stm32f1xx_it.c Interrupt handlers
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- TIM/TIM_InputCapture/Src/main.c Main program
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- TIM/TIM_InputCapture/Src/stm32f1xx_hal_msp.c HAL MSP file
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- TIM/TIM_InputCapture/Src/system_stm32f1xx.c STM32F1xx system source file
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@par Hardware and Software environment
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- This example runs on STM32F103xG devices.
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- In this example, the clock is set to 72 MHz.
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- This example has been tested with STMicroelectronics STM3210E-EVAL RevD
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board and can be easily tailored to any other supported device
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and development board.
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- STM3210E-EVAL RevD Set-up
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- Connect the external signal to measure to the TIM2 CH2 pin (PA.01).
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@par How to use it ?
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In order to make the program work, you must do the following :
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- Open your preferred toolchain
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- Rebuild all files and load your image into target memory
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- Run the example
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* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
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*/
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