STM32CubeF7/Projects/STM32F767ZI-Nucleo/Examples_LL/LPTIM/LPTIM_PulseCounter

/**
  @page LPTIM_PulseCounter LPTIM example
  
  @verbatim
  ******************************************************************************
  * @file    Examples_LL/LPTIM/LPTIM_PulseCounter/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the LPTIM_PulseCounter example.
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2016 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 LPTIM peripheral in counter mode to generate a PWM output signal 
and update its duty cycle. This example is based on the STM32F7xx
LPTIM LL API. The peripheral is initialized with LL unitary service 
functions to optimize for performance and size.

To reduce power consumption, MCU enters stop mode after starting counting. Each
time the counter reaches the maximum value (Period/Autoreload), an interruption
is generated, the MCU is woke up from stop mode and LED1 toggles the last state.
  
In this example Period value is set to 1000, so each time the counter counts
(1000 + 1) rising edges on LPTIM1_IN1 pin, an interrupt is generated and LED1
toggles. If the external function generator is set to provide a square waveform at 1Khz,
the led will toggle each second.

In this example the internal clock provided to the LPTIM1 is LSI (32 kHz),
so the external input is sampled with LSI clock. In order not to miss any event,
the frequency of the changes on the external Input1 signal should never exceed the
frequency of the internal clock provided to the LPTIM1 (LSI for the
present example).

@par Keywords

Timer, Low Power, Pulse Counter, Stop mode, Interrupt

@Note If the user code size exceeds the DTCM-RAM size or starts from internal cacheable memories (SRAM1 and SRAM2),that is shared between several processors,
      then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
      The address and the size of cacheable buffers (shared between CPU and other masters)  must be properly updated to be aligned to cache line size (32 bytes).

@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
      It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
      In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
      Even though the user must manage the cache coherence for read accesses.
      Please refer to the AN4838 “Managing memory protection unit (MPU) in STM32 MCUs”
      Please refer to the AN4839 “Level 1 cache on STM32F7 Series”

@par Directory contents 

  - LPTIM/LPTIM_PulseCounter/Inc/stm32f7xx_it.h          Interrupt handlers header file
  - LPTIM/LPTIM_PulseCounter/Inc/main.h                  Header for main.c module
  - LPTIM/LPTIM_PulseCounter/Inc/stm32_assert.h          Template file to include assert_failed function
  - LPTIM/LPTIM_PulseCounter/Src/stm32f7xx_it.c          Interrupt handlers
  - LPTIM/LPTIM_PulseCounter/Src/main.c                  Main program
  - LPTIM/LPTIM_PulseCounter/Src/system_stm32f7xx.c      STM32F7xx system source file


@par Hardware and Software environment

  - This example runs on STM32F767xx devices.
    
  - This example has been tested with NUCLEO-F767ZI board and can be
    easily tailored to any other supported device and development board.
    
  - Connect a square waveform generator to PD.12 (pin 21 in CN10 connector).
    If the frequency of the signal is 1 kHz, LED1 toggles every second.

@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


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