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

/*
    Copyright (C) 2017 GigaDevice

    2014-12-26, V1.0.0, platform GD32F1x0(x=5)
    2016-01-15, V2.0.0, platform GD32F1x0(x=5)
    2016-04-30, V3.0.0, firmware update for GD32F1x0(x=5)
    2017-06-19, V3.1.0, firmware update for GD32F1x0(x=5)
*/

  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 GD32F150xxx 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.
