wenkong_junshi/Examples/USBFS/USB_Device/cdc_acm

/*!
\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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This example is based on the GD32307C-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 GD32F30xxx 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.