AN571 Datasheet, PDF (1/26 Pages) Silicon Laboratories – VIRTUAL COM PORT INTERFACE

AN571
CP210X VIRTUAL COM PORT INTERFACE
1. Introduction
This document describes the CP210x Virtual COM Port interface between the host and CP210x device for the
purposes of creating custom drivers that interface with the CP210x. For more information on how to customize the
CP210x hardware, see “AN144: CP210x/CP211x Device Customization Guide” on the Silicon Labs Application
Notes webpage:
https://www.silabs.com/products/mcu/Pages/ApplicationNotes.aspx
1.1. Related Documents
Universal Serial Bus Specification: version 2.0 (also referred to as the USB Specification). This specification is
available at http://www.usb.org.
Universal Serial Bus Class Definitions for Communication Devices: version 1.1 (also referred to as the CDC
Specification, where “CDC” stands for “Communication Device Class”. This specification is available at http://
www.usb.org.
ANSI/TIA-602: Serial Asynchronous Automatic Dialing and Control - available at http://www.eia.org.
1.2. Terms
end device: refers to the hardware connected to the CP210x UART pins.
host: refers to the PC driver and host controller.
2. Interface Architecture
The CP210x device implements one or more communications interfaces implemented using the Bulk protocol.
These USB Bulk pipes transport data only and any status information must be obtained from the control pipe.
To configure and control the port, the host sends requests to the device via the control pipe. The host uses these
requests to perform such functions as setting the baud rate, setting handshaking modes, and configuring special
characters.
To send data from the host to the port, the host queues BULK-OUT packets to the endpoint of the interface
associated with the port. The data from these packets will be loaded into the interface’s data buffers and passed on
to the external device.
To move data from the port to the host, the host issues IN requests to the port’s data IN endpoint.
Rev. 0.1 12/10
Copyright © 2010 by Silicon Laboratories
AN571