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91 lines
4.2 KiB
Plaintext
91 lines
4.2 KiB
Plaintext
/**
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@page ADC_RegularConversion_DMA conversion using DMA for Data transfer
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@verbatim
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******************************************************************************
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* @file ADC/ADC_RegularConversion_DMA/readme.txt
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* @author MCD Application Team
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* @brief Description of the ADC RegularConversion DMA example.
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******************************************************************************
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* @attention
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*
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* Copyright (c) 2016 STMicroelectronics.
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* All rights reserved.
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*
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* This software is licensed under terms that can be found in the LICENSE file
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* in the root directory of this software component.
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* If no LICENSE file comes with this software, it is provided AS-IS.
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*
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******************************************************************************
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@endverbatim
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@par Example Description
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How to use the ADC1 and DMA to transfer continuously converted data from
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ADC1 to memory.
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The ADC1 is configured to convert continuously ADC_CHANNEL_10.
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Each time an end of conversion occurs the DMA transfers, in circular mode, the
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converted data from ADC1 DR register to the uhADCxConvertedValue variable.
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In this example, the system clock is 216MHz, APB2 = 108MHz and ADC clock = APB2/4.
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Since ADC1 clock is 27 MHz and sampling time is set to 3 cycles, the conversion
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time to 12bit data is 12 cycles so the total conversion time is (12+3)/27= 0.55us(1.81Msps).
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User can vary the ADC_CHANNEL_10 voltage by applying an input voltage on pin PC.00 (pin3 connector 9)
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(e.g. using function generator).
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STM32 board's LEDs can be used to monitor the transfer status:
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- LED1 is ON when the conversion is complete.
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- LED3 is ON when there is an error in ADC initialization, in ADC channel configuration
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or during conversion process.
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The converted value is monitored through debugger: uhADCxConvertedValue variable.
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The uhADCxConvertedValue read value is coded on 12 bits, the Vref+ reference voltage is connected
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on the board to VDD (+3.3V), the Vref- reference voltage is connected on the board to the ground.
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To convert the read value in volts, here is the equation to apply :
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Voltage = uhADCxConvertedValue * (Vref+ - Vref-) / (2^12) = uhADCxConvertedValue * 3.3 / 4096
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@par Keywords
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Analog, ADC, Analog to Digital Converter, Regular Conversion, DMA, Continuous Conversion
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@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,
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<20><><EFBFBD><EFBFBD><EFBFBD>then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>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).
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@Note It is recommended to enable the cache and maintain its coherence, but depending on the use case
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD> It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Even though the user must manage the cache coherence for read accesses.
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Please refer to the AN4838 <20>Managing memory protection unit (MPU) in STM32 MCUs<55>
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<EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Please refer to the AN4839 <20>Level 1 cache on STM32F7 Series<65>
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@par Directory contents
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- ADC/ADC_RegularConversion_DMA/Inc/stm32f7xx_hal_conf.h HAL configuration file
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- ADC/ADC_RegularConversion_DMA/Inc/stm32f7xx_it.h DMA interrupt handlers header file
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- ADC/ADC_RegularConversion_DMA/Inc/main.h Header for main.c module
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- ADC/ADC_RegularConversion_DMA/Src/stm32f7xx_it.c DMA interrupt handlers
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- ADC/ADC_RegularConversion_DMA/Src/main.c Main program
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- ADC/ADC_RegularConversion_DMA/Src/stm32f7xx_hal_msp.c HAL MSP file
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- ADC/ADC_RegularConversion_DMA/Src/system_stm32f7xx.c STM32F7xx system source file
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@par Hardware and Software environment
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- This example runs on STM32F767ZI devices.
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- This example has been tested with NUCLEO-F767ZI board and can be
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easily tailored to any other supported device and development board.
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@par How to use it ?
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In order to make the program work, you must do the following :
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- Open your preferred toolchain
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- Rebuild all files and load your image into target memory
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- Run the example
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*/
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