/*!
    \file    readme.txt
    \brief   description of the USB HID BCD

    \version 2025-08-08, V1.3.0, firmware for GD32E51x
*/

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*/

  This demo is based on the GD32E517Z-EVAL-V1.0 board, it provides a description of 
how to use the USB_Device peripheral.

  The GD32 device is enumerated as an USB keyboard, that uses the native PC Host
HID driver. The USB keyboard with Battery Charger Detection (BCD).

  The GD32E51x device supports charging port detection (BCD) described in Battery Charging 
Specification Revision 1.2.

   The GD32 include the capability to detect various USB battery chargers and can detect 
a range of USB battery chargers including a standard downstream port (SDP), a dedicated 
charging port (DCP), a charging downstream port (CDP), and a personal system 2 port (PS2).

  For more information on USB battery charger detection, please see the USB BDC 1.2.

  In this example, we use GD32 board LEDs to indicate the following connection status events:
    - LED1 for detection of SDP (host port without charging capability)
    - LED2 for detection of DCP (host port with charging capability)
    - LED3 for detection of CDP (Charger with short circuit between D+ and D-)
    - LED4 for detection of PS2

  For keyboard specific operation method, please refer to hid_keboard demo.

  Note: In BCD test, power on the development board first, and then insert USB line to PD port.
