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102 lines
4.8 KiB
Plaintext
102 lines
4.8 KiB
Plaintext
/**
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@page TIM_InputCapture Input Capture example
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@verbatim
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******************** (C) COPYRIGHT 2017 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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*
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* Redistribution and use in source and binary forms, with or without modification,
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* are permitted provided that the following conditions are met:
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* 1. Redistributions of source code must retain the above copyright notice,
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* this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright notice,
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* this list of conditions and the following disclaimer in the documentation
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* and/or other materials provided with the distribution.
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* 3. Neither the name of STMicroelectronics nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
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* AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
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* DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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******************************************************************************
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@endverbatim
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@par Example Description
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This example shows how to use the TIM peripheral to measure the frequency of
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an external signal.
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The TIM3CLK frequency is set to SystemCoreClock (Hz), the Prescaler is 0,
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so the TIM3 counter clock is SystemCoreClock (Hz).
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SystemCoreClock is set to 180 MHz for STM32F446xx Devices.
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TIM3 is configured in Input Capture Mode: the external signal is connected to
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TIM3 Channel2 used as input pin.
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To measure the frequency we use the TIM3 CC2 interrupt request, so in the
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TIM3_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 = TIM3 counter clock / uwDiffCapture (Hz),
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where "uwDiffCapture" is the difference between two consecutive TIM3 captures.
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The minimum frequency value to measure is TIM3 counter clock / CCR MAX
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= 180 MHz / 65535
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Due to TIM3_IRQHandler processing time (around 2.5us), the maximum
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frequency value to measure is around 400kHz.
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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/stm32f4xx_hal_conf.h HAL configuration file
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- TIM/TIM_InputCapture/Inc/stm32f4xx_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/stm32f4xx_it.c Interrupt handlers
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- TIM/TIM_InputCapture/Src/main.c Main program
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- TIM/TIM_InputCapture/Src/stm32f4xx_hal_msp.c HAL MSP file
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- TIM/TIM_InputCapture/Src/system_stm32f4xx.c STM32F4xx system source file
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@par Hardware and Software environment
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- This example runs on STM32F446xx devices.
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- In this example, the clock is set to 180 MHz.
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- This example has been tested with STMicroelectronics NUCLEO-446ZE Rev.B
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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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- NUCLEO-446ZE Set-up
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- Connect the external signal to measure to the TIM3 CH2 pin (PB.05).
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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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