STM32CubeF4

/**
  @page TIM_OCToggle TIM Output Compare Toggle 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 
  *          delayed signals.
  ******************************************************************************
  * @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 TIM3CLK frequency is set to SystemCoreClock / 2 (Hz), and we want to get TIM3
counter clock at 21 MHz so the Prescaler is computed as following:
- Prescaler = (TIM3CLK / TIM3 counter clock) - 1
SystemCoreClock is set to 180 MHz for STM32F4xx devices

The TIM3 CCR1 register value is equal to 40961: 
CC1 update rate = TIM3 counter clock / CCR1_Val = 439.44 Hz,
so the TIM3 Channel 1 generates a periodic signal with a frequency equal to 219.72 Hz.

The TIM3 CCR2 register is equal to 20480:
CC2 update rate = TIM3 counter clock / CCR2_Val = 878.9 Hz
so the TIM3 channel 2 generates a periodic signal with a frequency equal to 439.45 Hz.

The TIM3 CCR3 register is equal to 10240:
CC3 update rate = TIM3 counter clock / CCR3_Val = 1757.81 Hz
so the TIM3 channel 3 generates a periodic signal with a frequency equal to 878.9 Hz.

The TIM3 CCR4 register is equal to 5120:
CC4 update rate = TIM3 counter clock / CCR4_Val =  3515.62 Hz
so the TIM3 channel 4 generates a periodic signal with a frequency equal to 1757.81 Hz.


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

@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                   Main program header file  
  - 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 module
  - TIM/TIM_OCToggle/Src/system_stm32f4xx.c      STM32F4xx system clock configuration file

      
@par Hardware and Software environment 

  - This example runs on STM32F429xx/STM32F439xx devices.
    
  - This example has been tested with STMicroelectronics STM324x9I-EVAL RevB 
    evaluation boards and can be easily tailored to any other supported device and development board

  - STM324x9I-EVAL RevB Set-up 
    - Connect the TIM3 pins to an oscilloscope to monitor the different waveforms:
       - PC.06 (TIM3_CH1)
       - PC.07 (TIM3_CH2)
       - PC.08 (TIM3_CH3)
       - PC.09 (TIM3_CH4) 


@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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