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/**
@page TIM_PWMInput TIM PWM Input example
@verbatim
******************************************************************************
* @file TIM/TIM_PWMInput/readme.txt
* @author MCD Application Team
* @brief Description of the TIM PWM_Input example.
******************************************************************************
*
* Copyright (c) 2019-2021 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
How to use the TIM peripheral to measure the frequency and
duty cycle of an external signal.
The TIM2CLK frequency is set to SystemCoreClock (Hz), the Prescaler is 0 so the
counter clock is SystemCoreClock (Hz).
SystemCoreClock is set to 64 MHz for STM32WB55RGVx Devices.
TIM2 is configured in PWM Input Mode: the external signal is connected to
TIM2 Channel2 used as input pin.
To measure the frequency and the duty cycle, we use the TIM2 CC2 interrupt request,
so in the timer IRQ routine (via call to function HAL_TIM_IC_CaptureCallback() ),
the frequency and the duty cycle of the external signal are computed.
"uwFrequency" variable contains the external signal frequency:
TIM2 counter clock = SystemCoreClock,
uwFrequency = TIM2 counter clock / TIM2_CCR2 in Hz,
"uwDutyCycle" variable contains the external signal duty cycle:
uwDutyCycle = (TIM2_CCR1*100)/(TIM2_CCR2) in %.
The minimum frequency value to measure is (TIM2 counter clock / CCR MAX)
= (64 MHz)/ 65535
In case of error, LED3 is turned ON.
@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 This example needs to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.
@par Keywords
Timer, Input, signals, PWM, External signal, Frequency, Duty cycle, Measure
@par Directory contents
- TIM/TIM_PWMInput/Inc/stm32wbxx_hal_conf.h HAL configuration file
- TIM/TIM_PWMInput/Inc/stm32wbxx_it.h Interrupt handlers header file
- TIM/TIM_PWMInput/Inc/main.h Header for main.c module
- TIM/TIM_PWMInput/Src/stm32wbxx_it.c Interrupt handlers
- TIM/TIM_PWMInput/Src/main.c Main program
- TIM/TIM_PWMInput/Src/stm32wbxx_hal_msp.c HAL MSP file
- TIM/TIM_PWMInput/Src/system_stm32wbxx.c STM32WBxx system source file
@par Hardware and Software environment
- This example runs on STM32WB55xx devices.
- This example has been tested with STMicroelectronics P-NUCLEO-WB55
board and can be easily tailored to any other supported device
and development board.
- P-NUCLEO-WB55 Set-up
- Connect the external signal to measure to the TIM2 CH2 pin (PA1) (pin 32 in CN7 connector).
@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
* <h3><center>© COPYRIGHT STMicroelectronics</center></h3>
*/
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