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99 lines
4.8 KiB
Plaintext
99 lines
4.8 KiB
Plaintext
/**
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@page TIM_PWMInput TIM_PWMInput example
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@verbatim
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******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
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* @file TIM/TIM_PWMInput/readme.txt
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* @author MCD Application Team
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* @brief Description of the TIM PWM_Input 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 and
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duty cycle of an external signal.
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The TIM4CLK frequency is set to SystemCoreClock/4 (Hz), the Prescaler is 0 so the
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counter clock is SystemCoreClock/2 (Hz).
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SystemCoreClock is set to 84 MHz for STM32F401xCx Devices.
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TIM4 is configured in PWM Input Mode: the external signal is connected to
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TIM4 Channel2 used as input pin.
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To measure the frequency and the duty cycle we use the TIM4 CC2 interrupt request,
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so In the TIM4_IRQHandler routine, the frequency and the duty cycle of the external
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signal are computed.
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The "uwFrequency" variable contains the external signal frequency:
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TIM4 counter clock = SystemCoreClock,
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Frequency = TIM4 counter clock / TIM4_CCR2 in Hz,
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The "uwDutyCycle" variable contains the external signal duty cycle:
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DutyCycle = (TIM4_CCR1*100)/(TIM4_CCR2) in %.
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The minimum frequency value to measure is (TIM4 counter clock / CCR MAX)
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= (84MHz)/ 65535
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= 1680 Hz
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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 needs 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_PWMInput/Inc/stm32f4xx_hal_conf.h HAL configuration file
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- TIM/TIM_PWMInput/Inc/stm32f4xx_it.h Interrupt handlers header file
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- TIM/TIM_PWMInput/Inc/main.h Main program header file
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- TIM/TIM_PWMInput/Src/stm32f4xx_it.c Interrupt handlers
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- TIM/TIM_PWMInput/Src/main.c Main program
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- TIM/TIM_PWMInput/Src/stm32f4xx_hal_msp.c HAL MSP module
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- TIM/TIM_PWMInput/Src/system_stm32f4xx.c STM32F4xx system clock configuration file
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@par Hardware and Software environment
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- This example runs on STM32F401xCx devices.
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- This example has been tested with STMicroelectronics STM32F401-Discovery RevB board (MB1115B)
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and can be easily tailored to any other supported device and development board
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- STM32F401-Discovery RevB Set-up
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- Connect the external signal to measure to the TIM4 CH2 pin (PB.07).
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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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