STM32CubeF7/Projects/STM32F723E-Discovery/Examples/ADC/ADC_RegularConversion_DMA

/**
  @page ADC_RegularConversion_DMA conversion using DMA for Data transfer

  @verbatim
  ******************************************************************************
  * @file    ADC/ADC_RegularConversion_DMA/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the ADC RegularConversion DMA example.
  ******************************************************************************
  *
  * Copyright (c) 2016 STMicroelectronics. All rights reserved.
  *
  * This software component is licensed by ST under BSD 3-Clause license,
  * the "License"; You may not use this file except in compliance with the
  * License. You may obtain a copy of the License at:
  *                       opensource.org/licenses/BSD-3-Clause
  *
  ******************************************************************************
  @endverbatim

@par Example Description 

How to use the ADC3 and DMA to transfer continuously converted data from 
ADC3 to memory.

The ADC3 is configured to convert continuously ADC_CHANNEL_8.

Each time an end of conversion occurs the DMA transfers, in circular mode, the
converted data from ADC3 DR register to the uhADCxConvertedValue variable.

In this example, the system clock is 216MHz, APB2 = 108MHz and ADC clock = APB2/4. 
Since ADC3 clock is 27 MHz and sampling time is set to 3 cycles, the conversion 
time to 12bit data is 12 cycles so the total conversion time is (12+3)/25= 0.55us(1.8Msps).

User can vary the ADC_CHANNEL_8 voltage by applying an input voltage on pin PF10 connected to Arduino CN15 pin A3 
(e.g. using function generator).

STM32F723E-Discovery 's LEDs can be used to monitor the transfer status:
  - LED6 is ON when the conversion is complete.
  - LED5 is ON when there is an error in ADC initialization, in ADC channel configuration 
    or during conversion process.
The converted value is monitored through debugger: uhADCxConvertedValue variable.
The uhADCxConvertedValue read value is coded on 12 bits, the Vref+ reference voltage is connected 
on the board to VDD (+3.3V), the Vref- reference voltage is connected on the board to the ground.
To convert the read value in volts, here is the equation to apply :
Voltage = uhADCxConvertedValue * (Vref+ - Vref-) / (2^12) = uhADCxConvertedValue * 3.3 / 4096

@par Keywords

Analog, ADC, Analog to Digital Converter, Regular Conversion, DMA, Continuous Conversion

@Note<74>If the user code size exceeds the DTCM-RAM size or starts from internal cacheable memories (SRAM1 and SRAM2),that is shared between several processors,
 <20><><A0><A0><A0>then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
<0A><><A0><A0><A0><A0>The address and the size of cacheable buffers (shared between CPU and other masters)  must be properly updated to be aligned to cache line size (32 bytes).

@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
<0A><><A0><A0><A0> It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
<0A><><A0><A0><A0><A0>In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
<0A><><A0><A0><A0><A0>Even though the user must manage the cache coherence for read accesses.
<0A><><A0><A0><A0><A0>Please refer to the AN4838 <20>Managing memory protection unit (MPU) in STM32 MCUs<55>
<0A><><A0><A0><A0><A0>Please refer to the AN4839 <20>Level 1 cache on STM32F7 Series<65>

@par Directory contents 

  - ADC/ADC_RegularConversion_DMA/Inc/stm32f7xx_hal_conf.h    HAL configuration file
  - ADC/ADC_RegularConversion_DMA/Inc/stm32f7xx_it.h          DMA interrupt handlers header file
  - ADC/ADC_RegularConversion_DMA/Inc/main.h                  Header for main.c module  
  - ADC/ADC_RegularConversion_DMA/Src/stm32f7xx_it.c          DMA interrupt handlers
  - ADC/ADC_RegularConversion_DMA/Src/main.c                  Main program
  - ADC/ADC_RegularConversion_DMA/Src/stm32f7xx_hal_msp.c     HAL MSP file 
  - ADC/ADC_RegularConversion_DMA/Src/system_stm32f7xx.c      STM32F7xx system source file

@par Hardware and Software environment 

  - This example runs on STM32F722xx/STM32F723xx/STM32F732xx/STM32F733xx devices.
  
  - This example has been tested with STM32F723E-DISCOVERY 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>
 */