/**
  @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) 2020 STMicroelectronics. All rights reserved.
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                       opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  @endverbatim

@par Example Description 

How to use the TIM peripheral to measure the frequency and 
duty cycle of an external signal.

The TIM1CLK frequency is set to SystemCoreClock (Hz), the Prescaler is 0 so the 
counter clock is SystemCoreClock (Hz).
SystemCoreClock is set to 48 MHz for STM32WL55JCIx Devices.

TIM1 is configured in PWM Input Mode: the external signal is connected to 
TIM1 Channel2 used as input pin.
To measure the frequency and the duty cycle, we use the TIM1 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:
TIM1 counter clock = SystemCoreClock,
uwFrequency = TIM1 counter clock / TIM1_CCR2 in Hz, 

"uwDutyCycle" variable contains the external signal duty cycle:
uwDutyCycle = (TIM1_CCR1*100)/(TIM1_CCR2) in %.

The minimum frequency value to measure is (TIM1 counter clock / CCR MAX)
                                         = (48 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/stm32wlxx_nucleo_conf.h     BSP configuration file
  - TIM/TIM_PWMInput/Inc/stm32wlxx_hal_conf.h    HAL configuration file
  - TIM/TIM_PWMInput/Inc/stm32wlxx_it.h          Interrupt handlers header file
  - TIM/TIM_PWMInput/Inc/main.h                  Header for main.c module  
  - TIM/TIM_PWMInput/Src/stm32wlxx_it.c          Interrupt handlers
  - TIM/TIM_PWMInput/Src/main.c                  Main program
  - TIM/TIM_PWMInput/Src/stm32wlxx_hal_msp.c     HAL MSP file
  - TIM/TIM_PWMInput/Src/system_stm32wlxx.c      STM32WLxx system source file


@par Hardware and Software environment

  - This example runs on STM32WL55JCIx devices.
    
  - This example has been tested with STMicroelectronics NUCLEO-WL55JC RevC 
    board and can be easily tailored to any other supported device 
    and development board.

  - NUCLEO-WL55JC RevC Set-up
    - Connect the external signal to measure to the TIM1 CH2 pin (PA9) (pin 19 in CN10 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>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */