/**
  @page HID_Standalone USB Device Humain Interface (HID) example

  @verbatim
  ******************** (C) COPYRIGHT 2014 STMicroelectronics *******************
  * @file    USB_Device/HID_Standalone/readme.txt
  * @author  MCD Application Team
  * @version V1.1.0
  * @date    18-June-2014
  * @brief   Description of the USB HID example.
  ******************************************************************************
  *
  * Licensed under MCD-ST Liberty SW License Agreement V2, (the "License");
  * You may not use this file except in compliance with the License.
  * You may obtain a copy of the License at:
  *
  *        http://www.st.com/software_license_agreement_liberty_v2
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  *
  ******************************************************************************
  @endverbatim

@par Example Description

This example is a part of the USB Device Library package using STM32Cube firmware. 

This is a typical example on how to use the USB peripheral in Device mode with HID class V1.11 
following the "Device Class Definition for Human Interface Devices (HID) Version 1.11 
Jun 27, 2001". The example is built around the USB device library and emulate the joystick by moving 
the host mouse pointer horizontally.

This example supports the remote wakeup feature (the ability to bring the USB suspended bus back
to the active condition), and the Key button is used as the remote wakeup source. 
   
By default, in Windows OS, the USB mouse Power Management feature is turned off. This setting 
is different from classic PS/2 computer functionality. To enable the Wake up from  standby 
option, user has to manually turn on the Power Management feature for the USB mouse.

To enable the wake from standby option for the USB mouse, the following steps have to be followed: 
 - Start "Device Manager",
 - Select "Mice and other pointing devices",
 - Select the "HID-compliant mouse" device (make sure that PID &VID are equal to 0x5710 & 0x0483 respectively) 
 - Right click and select "Properties", 
 - Select "Power Management" tab,
 - Finally click to select "Allow this device to wake the computer" check box.

The function GetPointerData() is responsible to move the mouse cursor automatically,
which can be easily customized (square, circle...).
In this application the cursor is moving forward and backward in an infinite loop.

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).
In this application the system clock is set depending on the USB clock source 
  - 32 MHz from the PLL(HSE), when PLL is used as USB clock source
  - 16 MHz from the HSI, when HSI48 is used as USB clock source

The 48 MHz clock for the USB can be derived from one of the two following sources:
  – PLL clock(clocked by the HSE): If the USB uses the PLL as clock source, the PLL VCO clock must be programmed
    to output 96 MHz frequency (USBCLK = PLLVCO/2).
  – RC48 Clock (HSI48): The HSI48 clock is generated from an internal 48 MHz RC oscillator, coupled with
    the clock recovery system (CRS). 
    The CRS allows automatic trimming of the internal HSI48, synchronized with USB SOF signal at 1KHz rate, 
    to guarantee its optimal accuracy over the whole device operational range.    
User can select USB clock from HSI48 or PLL through macro defined in main.h
(USE_USB_CLKSOURCE_CRSHSI48 and USE_USB_CLKSOURCE_PLL).


@note Care must be taken when using HAL_Delay(), this function provides accurate delay (in milliseconds)
      based on the the SysTick ISR. Thus if HAL_Delay() is called from a peripheral ISR process, 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 or statically
      define it in the HAL configuration file through the "TICK_INT_PRIORITY" define.

@note The application needs to ensure that the SysTick time base is set to 1 millisecond
      to have correct HAL configuration.

@note To reduce the example footprint, the toolchain dynamic allocation is replaced by a static allocation
      by returning the address of a pre-defined static buffer with the HID class structure size.   


For more details about the STM32Cube USB Device library, please refer to UM1734 
"STM32Cube USB Device library".

@par Directory contents

  - USB_Device/HID_Standalone/Src/main.c                  Main program
  - USB_Device/HID_Standalone/Src/system_stm32l0xx.c      STM32L0xx system clock configuration file
  - USB_Device/HID_Standalone/Src/stm32l0xx_it.c          Interrupt handlers
  - USB_Device/HID_Standalone/Src/usbd_conf.c             General low level driver configuration
  - USB_Device/HID_Standalone/Src/usbd_desc.c             USB device HID descriptor
  - USB_Device/HID_Standalone/Inc/main.h                  Main program header file
  - USB_Device/HID_Standalone/Inc/stm32l0xx_it.h          Interrupt handlers header file
  - USB_Device/HID_Standalone/Inc/stm32l0xx_hal_conf.h    HAL configuration file
  - USB_Device/HID_Standalone/Inc/usbd_conf.h             USB device driver Configuration file
  - USB_Device/HID_Standalone/Inc/usbd_desc.h             USB device MSC descriptor header file


@par Hardware and Software environment

  - This example runs on STM32L052xx, STM32L053xx STM32L062xx and 
    STM32L063xx device lines RevZ.

  - This example has been tested with STM32L053R8-Nucleo RevC board with a USB shield daughter
   board, and can be easily tailored to any other supported device and development board.

  - STM32L053-Nucleo RevC Set-up
      Since there is no USB 2.0 Full speed connector (Type B) on the nucleo board, user has to make 
      his own USB shield daughter board with the a USB connector and plug it on top of the  CN11 and CN12 
      connectors of the STM32L053-Nucleo. The USB connector has to be connected to the USB device associated GPIOs
      as follows:
       - DP (D+ of the USB connector) <======> PA12 (Nucleo board)
       - DM (D- of the USB connector) <======> PA11 (Nucleo board)

      To improve EMC performance (noise immunity and signal integrity), it is recommended to connect a 100nF
      ceramic capacitor to the USB VDD pin.

@par How to use it ?

To use this example, the following steps have to be followed:
 - Open project file.
 - Rebuild all the project and load the image into the target memory
 - Run the example

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