STM32CubeF3

@verbatim
******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
* @file TIM/TIM_InputCapture/readme.txt
* @author MCD Application Team
* @brief Description of the TIM_InputCapture example.
******************************************************************************
* @attention
*
* <h2><center>&copy; Copyright (c) 2016 STMicroelectronics.
* All rights reserved.</center></h2>
*
* 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

Use of the TIM peripheral to measure an external signal frequency.

The TIM4CLK frequency is set to SystemCoreClock (Hz), the Prescaler is 0,
so the TIM4 counter clock is SystemCoreClock (Hz).
SystemCoreClock is set to 72 MHz for STM32F373xC Devices.

TIM4 is configured in Input Capture Mode: the external signal is connected to
TIM4 Channel2 used as input pin.
To measure the frequency we use the TIM4 CC2 interrupt request, so in the
TIM4_IRQHandler routine, the frequency of the external signal is computed.

The "uwFrequency" variable contains the external signal frequency:
uwFrequency = TIM4 counter clock / uwDiffCapture (Hz),
where "uwDiffCapture" is the difference between two consecutive TIM4 captures.

The minimum frequency value to measure is TIM4 counter clock / CCR MAX
= 72 MHz / 65535

Due to TIM4_IRQHandler processing time (around 3.50us), the maximum
frequency value to measure is around 300kHz.

@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 The application need to ensure that the SysTick time base is always set to 1 millisecond
to have correct HAL operation.

@par Directory contents

- TIM/TIM_InputCapture/Inc/stm32f3xx_hal_conf.h HAL configuration file
- TIM/TIM_InputCapture/Inc/stm32f3xx_it.h Interrupt handlers header file
- TIM/TIM_InputCapture/Inc/main.h Header for main.c module
- TIM/TIM_InputCapture/Src/stm32f3xx_it.c Interrupt handlers
- TIM/TIM_InputCapture/Src/main.c Main program
- TIM/TIM_InputCapture/Src/stm32f3xx_hal_msp.c HAL MSP file
- TIM/TIM_InputCapture/Src/system_stm32f3xx.c STM32F3xx system source file

@par Hardware and Software environment

- This example runs on STM32F373xC devices.
- In this example, the clock is set to 72 MHz.

- This example has been tested with STMicroelectronics STM32373C-EVAL RevB
board and can be easily tailored to any other supported device
and development board.

- STM32373C-EVAL RevB Set-up
- Connect the external signal to measure to the TIM4 CH2 pin (PB.07).

@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