/**
  @page MSC_Standalone USB Host Mass Storage (MSC) application
  
  @verbatim
  ******************************************************************************
  * @file    USB_Host/MSC_Standalone/readme.txt 
  * @author  MCD Application Team
  * @brief   Description of the USB Host MSC application.
  ******************************************************************************
  *
  * @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 Application Description

Use of the USB host application based on the Mass Storage Class (MSC).

This is a typical application on how to use the STM32F7xx USB OTG Host peripheral to operate with an USB 
flash disk using the Bulk Only Transfer (BOT) and Small Computer System Interface (SCSI) transparent
commands combined with a file system FatFs (Middleware component).

At the beginning of the main program the HAL_Init() function is called to reset all the peripherals,
initialize the Flash interface and the systick. The user is provided with the SystemClock_Config()
function to configure the system clock (SYSCLK) to run at 200 Mhz. The Full Speed (FS) USB module uses
internally a 48-MHz clock which is coming from a specific output of two PLLs: main PLL or PLL SAI.
In the High Speed (HS) mode the USB clock (60 MHz) is driven by the ULPI.

When the application is started, the connected USB flash disk device is detected in MSC mode and gets 
initialized. The STM32 MCU behaves as a MSC Host, it enumerates the device and extracts VID, PID, 
manufacturer name, Serial no and product name information and displays it on the LCD screen. 
This application is based on read/write file and explore the USB flash disk content through a MSC routine.

User can start any operations using User button:
 - "File Operations" operation writes a small text file (less to 1 KB) on the USB flash disk.
 - "Explorer Disk" operation explores the USB flash disk content and displays it on the LCD screen.
    User has to press the User button to display the whole USB flash disk content (recursion level 2).

@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.

@note The STM32F7xx devices can reach a maximum clock frequency of 216MHz but as this application 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.

For more details about the STM32Cube USB Host library, please refer to UM1720  
"STM32Cube USB Host library".


@par USB Library Configuration

To select the appropriate USB Core to work with, user must add the following macro defines within the
compiler preprocessor (already done in the preconfigured projects provided with this application):
      - "USE_USB_HS" when using USB High Speed (HS) Core

It is possible to fine tune needed USB Host features by modifying defines values in USBH configuration
file “usbh_conf.h” available under the project includes directory, in a way to fit the application
requirements, such as:
                  0: No debug messages
                  1: Only User messages are shown
                  2: User and Error messages are shown
                  3: All messages and internal debug messages are shown
   By default debug messages are displayed on the debugger IO terminal; to redirect the Library
   messages on the LCD screen, lcd_log.c driver need to be added to the application sources.


@par Keywords

Connectivity, USB_Host, USB, MSC, Mass Storage, Full Speed, High Speed, BOT, SCSI, Removable drive, FatFs,
File system, Write, Read, Format

@Note 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,
      then it is highly recommended to enable the CPU cache and maintain its coherence at application level.
      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
      It is also possible to configure the MPU as "Write through", to guarantee the write access coherence.
      In that case, the MPU must be configured as Cacheable/Bufferable/Not Shareable.
      Even though the user must manage the cache coherence for read accesses.
      Please refer to the AN4838 “Managing memory protection unit (MPU) in STM32 MCUs”
      Please refer to the AN4839 “Level 1 cache on STM32F7 Series”

@par Directory contents

  - USB_Host/MSC_Standalone/Src/main.c                  Main program
  - USB_Host/MSC_Standalone/Src/STM32F7xx_it.c          Interrupt handlers
  - USB_Host/MSC_Standalone/Src/menu.c                  MSC State Machine
  - USB_Host/MSC_Standalone/Src/usbh_conf.c             General low level driver configuration
  - USB_Host/MSC_Standalone/Src/explorer.c              Explore the USB flash disk content
  - USB_Host/MSC_Standalone/Src/file_operations.c       Write/read file on the disk
  - USB_Host/MSC_Standalone/Src/system_STM32F7xx.c      STM32F7xx system clock configuration file
  - USB_Host/MSC_Standalone/Inc/main.h                  Main program header file
  - USB_Host/MSC_Standalone/Inc/STM32F7xx_it.h          Interrupt handlers header file
  - USB_Host/MSC_Standalone/Inc/lcd_log_conf.h          LCD log configuration file
  - USB_Host/MSC_Standalone/Inc/STM32F7xx_hal_conf.h    HAL configuration file
  - USB_Host/MSC_Standalone/Inc/usbh_conf.h             USB Host driver Configuration file
  - USB_Host/MSC_Standalone/Inc/ffconf.h                FatFs Module Configuration file
 

@par Hardware and Software environment

  - This application runs on STM32F769xx/STM32F779xx devices.
    
  - This application has been tested with STMicroelectronics STM32F769I-Discovery
    boards and can be easily tailored to any other supported device 
    and development board.

  - STM32F769I-Discovery Set-up
    - Plug the USB key into the STM32F769I-Discovery board through 'USB micro A-Male 
      to A-Female' cable to the connector:
      - CN15 : to use USB High Speed (HS) 

@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
 - In the workspace toolbar select the project configuration:
   - STM32F769I-Discovery: to configure the project for STM32F7xx devices using USB OTG HS peripheral
 - Run the application
 

 */