/**
  @page TIM_PWMOutput TIM PWM Output example
  
  @verbatim
  ******************** (C) COPYRIGHT 2016 STMicroelectronics *******************
  * @file    TIM/TIM_PWMOutput/readme.txt 
  * @author  MCD Application Team
  * @version V1.5.0
  * @date    14-April-2017
  * @brief   Description of the PWM signals generation using TIM2
  ******************************************************************************
  *
  * 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
  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  * CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  *
  ******************************************************************************
  @endverbatim

@par Example Description 

Configuration of the TIM peripheral in PWM (pulse width modulation) mode.

SystemCoreClock is set to 72 MHz for STM32F1xx Devices.

    In this example TIM2 input clock (TIM2CLK) is set to APB1 clock (PCLK1) x2,
    since APB1 prescaler is set to 4 (0x100).
       TIM2CLK = PCLK1*2
       PCLK1   = HCLK/2
    => TIM2CLK = PCLK1*2 = (HCLK/2)*2 = HCLK = SystemCoreClock

    To get TIM2 counter clock at 2.1 MHz, the prescaler is computed as follows:
       Prescaler = (TIM2CLK / TIM2 counter clock) - 1
       Prescaler = ((SystemCoreClock) /2.1 MHz) - 1

    To get TIM2 output clock at 3 KHz, the period (ARR)) is computed as follows:
       ARR = (TIM2 counter clock / TIM2 output clock) - 1
           = 699

    TIM2 Channel1 duty cycle = (TIM2_CCR1/ TIM2_ARR + 1)* 100 = 50%
    TIM2 Channel2 duty cycle = (TIM2_CCR2/ TIM2_ARR + 1)* 100 = 37.5%
    TIM2 Channel3 duty cycle = (TIM2_CCR3/ TIM2_ARR + 1)* 100 = 25%
    TIM2 Channel4 duty cycle = (TIM2_CCR4/ TIM2_ARR + 1)* 100 = 12.5%


The PWM waveforms can be displayed using an oscilloscope.

@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_PWMOutput/Inc/stm32f1xx_hal_conf.h    HAL configuration file
  - TIM/TIM_PWMOutput/Inc/stm32f1xx_it.h          Interrupt handlers header file
  - TIM/TIM_PWMOutput/Inc/main.h                  Header for main.c module  
  - TIM/TIM_PWMOutput/Src/stm32f1xx_it.c          Interrupt handlers
  - TIM/TIM_PWMOutput/Src/main.c                  Main program
  - TIM/TIM_PWMOutput/Src/stm32f1xx_hal_msp.c     HAL MSP file
  - TIM/TIM_PWMOutput/Src/system_stm32f1xx.c      STM32F1xx system source file


@par Hardware and Software environment

  - This example runs on STM32F103xG devices.
  - In this example, the clock is set to 72 MHz.
    
  - This example has been tested with STMicroelectronics STM3210E-EVAL RevD 
    board and can be easily tailored to any other supported device 
    and development board.      

  - STM3210E-EVAL RevD Set-up
   Connect the following pins to an oscilloscope to monitor the different waveforms:
        - TIM2_CH1 : PA.0  (On Eval Board, pin 31 on CN1  for example)
        - TIM2_CH2 : PA.1  (On Eval Board, pin 33 on CN1  for example)
        - TIM2_CH3 : PA.2  (On Eval Board, pin 34 on CN1  for example)
        - TIM2_CH4 : PA.3  (On Eval Board, pin 58 on CN11 for example)


@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>
 */
