wenkong_junshi/Examples/USBD/cdc_acm/readme.txt

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

    \version 2023-06-30, V2.1.6, firmware for GD32F30x
*/

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*/

  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 GD32F30x 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.