/**
  @page HAL_TimeBase HAL Time base example
  
  @verbatim
  ******************** (C) COPYRIGHT 2014 STMicroelectronics *******************
  * @file    HAL/HAL_TimeBase/readme.txt 
  * @author  MCD Application Team
  * @version V1.0.0
  * @date    18-June-2014
  * @brief   Description of the HAL time base example.
  ******************************************************************************
  *
  * Redistribution and use in source and binary forms, with or without modification,
  * are permitted provided that the following conditions are met:
  *   1. Redistributions of source code must retain the above copyright notice,
  *      this list of conditions and the following disclaimer.
  *   2. Redistributions in binary form must reproduce the above copyright notice,
  *      this list of conditions and the following disclaimer in the documentation
  *      and/or other materials provided with the distribution.
  *   3. Neither the name of STMicroelectronics nor the names of its contributors
  *      may be used to endorse or promote products derived from this software
  *      without specific prior written permission.
  *
  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
  * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
  * DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  @endverbatim

@par Example Description 

This example describes how to customize the HAL time base using a general 
purpose timer(TIM6) instead of Systick as main source of time base.

Time base duration is kept unchanged: 1ms  since PPP_TIMEOUT_VALUEs are defined 
and handled in milliseconds basis.

The example brings, in user file, a new implementation of the following HAL weak functions:

HAL_InitTick() 
HAL_SuspendTick()
HAL_ResumeTick()

This implementation will overwrite native implementation in stm32l0xx_hal.c
and so user functions will be invoked instead when called.

The following time base functions are kept as implemented natively:

HAL_IncTick()
HAL_Delay()
HAL_IncTick()

When user pushes the Push-button Tick increment is suspended if it is already
enabled, else it will be resumed.
In an infinite loop, LED3 toggles spaced out over 1s delay.


@note Care must be taken when using HAL_Delay(), this function provides accurate
      delay (in milliseconds) based on variable incremented in TIM6 ISR. 
      This implies that if HAL_Delay() is called from a peripheral ISR process, 
      then the TIM6 interrupt must have higher priority (numerically lower)
      than the peripheral interrupt. Otherwise the caller ISR process will be blocked.
      To change the TIM6 interrupt priority you have to use HAL_NVIC_SetPriority() function.
      
@note The application need to ensure that the TIM6 time base is always set to 1 
      millisecond to have correct HAL operation.

@par Directory contents  

  - HAL/HAL_TimeBase/Inc/stm32l0xx_hal_conf.h    HAL configuration file
  - HAL/HAL_TimeBase/Inc/stm32l0xx_it.h          Interrupt handlers header file
  - HAL/HAL_TimeBase/Inc/main.h                  Header for main.c module  
  - HAL/HAL_TimeBase/Src/stm32l0xx_it.c          Interrupt handlers
  - HAL/HAL_TimeBase/Src/main.c                  Main program
  - HAL/HAL_TimeBase/Src/stm32l0xx_hal_msp.c     HAL MSP module
  - HAL/HAL_TimeBase/Src/system_stm32l0xx.c      STM32L0xx system source file


@par Hardware and Software environment

  - This example runs on STM32L051xx, STM32L052xx, STM32L053xx STM32L062xx and 
    STM32L063xx device lines RevZ
    
  - This example has been tested with STM32L0538-DISCO RevB  board and can be
    easily tailored to any other supported device and development board.      


@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>
 */
