GD32F3x0_Firmware_Library/Projects/USBFS/USB_Device/CDC_ACM/readme.txt

/*!
    \file  readme.txt
    \brief description of the USB CDC_ACM demo
*/

/*
    Copyright (C) 2017 GigaDevice

    2017-06-06, V1.0.0, firmware for GD32F3x0
*/

   This example is based on the GD32350R-EVAL board,it provides a description of 
 how to use the USBFS.

  The target of this example is to read data from and write data to USB devices using 
the CDC protocol.
 
  It makes the USB device look like a serial port (NO serial cable connectors: You 
can see the data transferred to and from via USB instead of USB-to-USART bridge connection).
 
  This example loops back the contents of a text file over usb port. To run the example, 
Type a message using the Pc's keyboard. Any data that shows in HyperTerminal is received 
from the device.

  This CDC_ACM Demo provides the firmware examples for the GD32F350xx families.

  - OUT transfers (receive the data from the PC to GD32):
  When a packet is received from the PC on the OUT pipe (EP3),by calling cdc_acm_data_receive()
  it will be stored in the usb_data_buffer[]. 
 
  - IN transfers (to send the data received from the GD32 to the PC):
  When a packet is sent from the GD32 on the IN pipe (EP1), by calling cdc_acm_data_send(),
  put the data into the usb_data_buffer[] buffer for sending data to the host.