STM32CubeF7/Projects/STM32F769I_EVAL/Examples/JPEG/JPEG_DecodingUsingFs_Polling/readme.txt

/**
  @page JPEG_DecodingUsingFs_Polling : JPEG example : JPEG decoding using Fatfs and with Polling example

  @verbatim
  ******************************************************************************
  * @file    JPEG/JPEG_DecodingUsingFs_Polling/readme.txt
  * @author  MCD Application Team
  * @brief   Description of the JPEG decoding using Fatfs and with Polling 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

This example demonstrates how to read jpeg file from SDCard memory using Fatfs, decode it
using the JPEG HW decoder in polling mode and display the final ARGB8888 image on KoD LCD
mounted on board or a HDMI monitor Connected through the DSI-HDMI bridge board MB1232.A.

The example can automatically detect if the KoD LCD is connected or if the DSI-HDMI
bridge is connected to the DSI connector (CN15), if no DSI slave is connected the RED LED will turn On.

The example performs the following actions :
  - Link the uSD disk I/O driver.
  - Register the file system object (mount) to the FatFs module for the uSD drive.
  - Open the jpg file "image.jpg" in read access.
  - Call the function "JPEG_DecodePolling" to start decoding the jpg file with Polling (blocking method).
    Function "JPEG_DecodePolling" is implemented in a separate module decode_polling.c.
    This module is a wrapper on top of the JPEG HAL driver

  - Once the decoding ends,
    - Call HAL routine "HAL_JPEG_GetInfo" to retrieve the image parameters :
      image width, image height, image quality (from 1% to 100%) color space and Chroma sampling.
    - copy the ARGB8888 result buffer to the LCD Frame buffer for display:
        Using the DMA2D and positioning the image in the center of the LCD screen.
    - Close the jpg file.

@note To run this example , you can use an JPEG <20>.jpg<70> file from\Utilities\Media\Pictures\JPG
      or use your own .jpg image.

@note The jpeg HW decoder outputs are organized in YCbCr blocks.
      The jpeg utilities functions implemented in "jpeg_utils.c" file are used to convert these YCbCr blocks
      to RGB pixels to the destination JPEG output buffer.
      The JPEG utilities files allowing to convert YCbCr blocks to RGB pixels are available under \Utilities\JPEG

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

@note The STM32F7xx devices can reach a maximum clock frequency of 216MHz but as this example uses SDRAM,
      the system clock is limited to 200MHz. Indeed proper functioning of the SDRAM is only guaranteed
      at a maximum system clock frequency of 200MHz.

@note The compiler optimizations level could be set to High/Balanced giving a good tradeoff between the code size and the performance (decode time).

@note In case of EVAL's LCD use in example code, the DATA_IN_ExtSDRAM define
      need to be added  in the project preprocessor to avoid SDRAM multiple configuration
     (the LCD uses SDRAM as frame buffer, and its configuration is done by the BSP_SDRAM_Init()).

@par Keywords

Display, Graphic, JPEG, Decoding, Flash memory, Polling, ARGB8888, Hardware decoding, LCD, HDMI, YCbCr, RGB,
FatFS, File system, SD Card, SDRAM

@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><><EFBFBD><EFBFBD><EFBFBD>then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
<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).

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

@par Directory contents

  - JPEG/JPEG_DecodingUsingFs_Polling/Inc/stm32f7xx_hal_conf.h          HAL configuration file
  - JPEG/JPEG_DecodingUsingFs_Polling/Inc/stm32f7xx_it.h                Interrupt handlers header file
  - JPEG/JPEG_DecodingUsingFs_Polling/Inc/ffconf.h                      FAT file system module configuration file
  - JPEG/JPEG_DecodingUsingFs_Polling/Inc/main.h                        Header for main.c module
  - JPEG/JPEG_DecodingUsingFs_Polling/Inc/sd_diskio.h                   FatFS sd diskio header file
  - JPEG/JPEG_DecodingUsingFs_Polling/Inc/decode_polling.h              Header for decode_polling.c module
  - JPEG/JPEG_DecodingUsingFs_Polling/Inc/jpeg_utils_conf.h             JPEG utilties module configuration file

  - JPEG/JPEG_DecodingUsingFs_Polling/Src/stm32f7xx_it.c                Interrupt handlers
  - JPEG/JPEG_DecodingUsingFs_Polling/Src/main.c                        Main program
  - JPEG/JPEG_DecodingUsingFs_Polling/Src/sd_diskio.c                   FatFS sd diskio implmentation
  - JPEG/JPEG_DecodingUsingFs_Polling/Src/decode_polling.c              JPEG Decoding with polling module
  - JPEG/JPEG_DecodingUsingFs_Polling/Src/stm32f7xx_hal_msp.c           HAL MSP module
  - JPEG/JPEG_DecodingUsingFs_Polling/Src/system_stm32f7xx.c            STM32F7xx system source file


@par Hardware and Software environment

  - This example runs on STM32F769xx/STM32F779xx devices.

  - This example has been tested with STMicroelectronics STM32F769I_EVAL revB
    evaluation boards and can be easily tailored to any other supported device
    and development board.

  - STM32F769I_EVAL Set-up
  - Copy a jpg image to a uSD card (under the root)
      The image must have the following properties:
        - named as "image.jpg"
        - dimensions : less or equal to the display screen:
           * LCD-DSI:
               - Witdh  : <= 800
               - Height : <= 480
           * HDMI-DSI:
               - Witdh  : <= 720
               - Height : <= 576
  - Connect the uSD Card to the uSD1 connector (CN17).

@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
 - Mount either the KoD LCD pannel (Board MB1166 rev.A) or the DSI-HDMI bridge(Board MB1232 Rev.A)
   to the DSI connector (CN15).
 - if using the DSI-HDMI bridge then connect a HDMI monitor using a HDMI cable to the
   MB1232 board.
 - Run the example

 * <h3><center>&copy; COPYRIGHT STMicroelectronics</center></h3>
 */