STM32CubeF4

/**
  @page TIM_OCToggle TIM_OCToggle example
  
  @verbatim
  ******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
  * @file    TIM/TIM_OCToggle/readme.txt 
  * @author  MCD Application Team
  * @brief   This example shows how to configure the Timer to generate four different 
  *          signals with four different frequencies.
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2017 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 

  This example shows how to configure the TIM peripheral to generate four different 
  signals with four different frequencies.

  The TIM1 frequency is set to SystemCoreClock, and the objective is
  to get TIM1 counter clock at 20 MHz so the Prescaler is computed as following:
     - Prescaler = (TIM1CLK /TIM1 counter clock) - 1
   
  SystemCoreClock is set to 180 MHz for STM32F4xx Devices.

  The TIM1 CCR1 register value is equal to 40961:
  CC1 update rate = TIM1 counter clock / CCR1_Val = 488.269 Hz,
  so the TIM1 Channel 1 generates a periodic signal with a frequency equal to 244.13 Hz.

  The TIM1 CCR2 register value is equal to 20480:
  CC2 update rate = TIM1 counter clock / CCR2_Val = 976.56 Hz,
  so the TIM1 channel 2 generates a periodic signal with a frequency equal to 488.28 Hz.

  The TIM1 CCR3 register value is equal to 10240:
  CC3 update rate = TIM1 counter clock / CCR3_Val = 1953.1 Hz,
  so the TIM1 channel 3 generates a periodic signal with a frequency equal to 976.56 Hz.

  The TIM1 CCR4 register value is equal to 5120:
  CC4 update rate = TIM1 counter clock / CCR4_Val =  3906.25 Hz,
  so the TIM1 channel 4 generates a periodic signal with a frequency equal to 1953.12 Hz.

@note PWM signal frequency values mentioned above are theoretical (obtained when the system clock frequency
      is exactly 180 MHz). Since the generated system clock frequency may vary from one board to another observed
      PWM signal frequency might be slightly different.
  
@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.

@note The connection of the LCD reset pin to a dedicated GPIO PK7 instead of the STM32F469 NRST pin may cause residual display on LCD with applications/examples that do not require display.
	  The LCD clear can be ensured by hardware through the boards power off/power on or by software calling the BSP_LCD_Reset() function.

@par Keywords

Timers, Output, signals, Output compare toggle, PWM, Oscilloscope

@par Directory contents 

  - TIM/TIM_OCToggle/Inc/stm32f4xx_hal_conf.h    HAL configuration file
  - TIM/TIM_OCToggle/Inc/stm32f4xx_it.h          Interrupt handlers header file
  - TIM/TIM_OCToggle/Inc/main.h                  Header for main.c module  
  - TIM/TIM_OCToggle/Src/stm32f4xx_it.c          Interrupt handlers
  - TIM/TIM_OCToggle/Src/main.c                  Main program
  - TIM/TIM_OCToggle/Src/stm32f4xx_hal_msp.c     HAL MSP file
  - TIM/TIM_OCToggle/Src/system_stm32f4xx.c      STM32F4xx system source file


@par Hardware and Software environment

  - This example runs on STM32F469xx/STM32F479xx devices.

  - This example has been tested and validated with STMicroelectronics STM32469I-EVAL RevC 
    board and can be easily tailored to any other supported device 
    and development board.      

  - STM32469I-EVAL Set-up
   Connect the following pins to an oscilloscope to monitor the different waveforms:
      - PA.08: (TIM1_CH1) (pin 52 in CN6 connector)
      - PA.09: (TIM1_CH2) (pin 43 in CN6 connector)
      - PA.10: (TIM1_CH3) (pin 44 in CN6 connector)
      - PE.14: (TIM1_CH4) (pin 21 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


 */