STM32CubeF4

/**
  @page TIM_6Steps TIM 6 Steps example
  
  @verbatim
  ******************** (C) COPYRIGHT 2017 STMicroelectronics *******************
  * @file    Examples_MIX/TIM/TIM_6Steps/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the TIM 6 Steps example.
  ******************************************************************************
  * @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 TIM1 peripheral to generate 6 Steps PWM
signal. The STM32F4xx TIM1 peripheral allows programming in advance the configuration
for the next TIM1 output behavior (or step) and changing the configuration of all the
channels simultaneously. This operation is possible when the COM (commutation) event
is used. This example is based on the STM32F4xx TIM HAL and LL API (LL API usage for
performance improvement).

The COM event can be generated by software by setting the COM bit in the TIM1_EGR
register or by hardware (on TRC rising edge).
In this example, a software COM event is generated each 1 ms: using the SysTick 
interrupt.

The TIM1 is configured in Timing Mode, each time a COM event occurs, a new TIM1
configuration will be set in advance. Only changed states are programmed. 

The break Polarity is used at High level.

The following Table describes the TIM1 Channels states:

@verbatim
                     -----------------------------------------------
                    | Step1 | Step2 | Step3 | Step4 | Step5 | Step6 |
          ----------------------------------------------------------
         |Channel1  | 1(PWM)|   0   |   0   |   0   |   0   |1(PWM) |
          ----------------------------------------------------------
         |Channel1N |   0   |   0   |1(PWM) |1(PWM) |   0   |   0   |
          ----------------------------------------------------------
         |Channel2  |   0   |   0   |   0   |1(PWM) |1(PWM) |   0   |
          ----------------------------------------------------------
         |Channel2N |1(PWM) |1(PWM) |   0   |   0   |   0   |   0   |
          ----------------------------------------------------------
         |Channel3  |   0   |1(PWM) |1(PWM) |   0   |   0   |   0   |
          ----------------------------------------------------------
         |Channel3N |   0   |   0   |   0   |   0   |1(PWM) |1(PWM) |
          -----------------------------------------------------------
 

 
                     . Step1 . Step2 . Step3 . Step4 . Step 5 . Step 6 . Step1 . Step2 . Step 3 . Step 4 . Step5 ... 

 Channel1  (PA.08)   |||||||||_________________________________|||||||||||||||||____________________________________
 Channel1N (PA.07)   ________________|||||||||||||||||__________________________________||||||||||||||||||__________
                                                    
 Channel2  (PA.09)   ________________________||||||||||||||||||_________________________________|||||||||||||||||___
 Channel2N (PB.00)   |||||||||||||||||_________________________________|||||||||||||||||____________________________    
                                                    
 Channel3  (PA.10)   ________|||||||||||||||||__________________________________||||||||||||||||||___________________
 Channel3N (PB.01)   _________________________________||||||||||||||||||__________________________________|||||||||||
   
@endverbatim

@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, 6 steps, PWM, Duty Cycle, Waveform, Oscilloscope, Output, Signal, commutation, timing mode

@par Directory contents 

  - Examples_MIX/TIM/TIM_6Steps/Inc/stm32f4xx_hal_conf.h    HAL configuration file
  - Examples_MIX/TIM/TIM_6Steps/Inc/stm32f4xx_it.h          Interrupt handlers header file
  - Examples_MIX/TIM/TIM_6Steps/Inc/main.h                  Header for main.c module  
  - Examples_MIX/TIM/TIM_6Steps/Src/stm32f4xx_it.c          Interrupt handlers
  - Examples_MIX/TIM/TIM_6Steps/Src/main.c                  Main program
  - Examples_MIX/TIM/TIM_6Steps/Src/system_stm32f4xx.c      STM32F4xx system source file
  - Examples_MIX/TIM/TIM_6Steps/Src/stm32f4xx_hal_msp.c     HAL MSP file    


@par Hardware and Software environment

  - This example runs on STM32F411xx devices.
    
  - This example has been tested with NUCLEO-F411RE board and can be
    easily tailored to any other supported device and development board.    

  - NUCLEO-F411RE Set-up
    - Connect the TIM1 pins to an oscilloscope to monitor the different waveforms:
      - TIM1_CH1  PA.08: connected to pin 8 of CN9 connector  
      - TIM1_CH1N PA.07: connected to pin 4 of CN5 connector 
      - TIM1_CH2  PA.09: connected to pin 1 of CN5 connector 
      - TIM1_CH2N PB.00: connected to pin 4 of CN8 connector 
      - TIM1_CH3  PA.10: connected to pin 3 of CN9 connector 
      - TIM1_CH3N PB.01: connected to pin 24 of CN10 connector 

    - Connect the TIM1 break to the GND. To generate a break event, switch this
      pin level from 0V to 3.3V.  
      - TIM1_BKIN  PA.06: connected to pin 5 of CN5 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


 */