CP2102N Datasheet, PDF (21/44 Pages) Silicon Laboratories – USBXpress Family

CP2102N Data Sheet
Functional Description
4.4.1 Virtual COM Port (VCP) Drivers
The CP2102N Virtual COM Port (VCP) device drivers allow a CP2102N-based USB device to appear to the PC's application software
as a COM port. Application software running on the PC accesses the CP2102N-based device as it would access a standard hardware
COM port. However, actual data transfer between the PC and the CP2102N device is performed over the USB interface. Therefore,
existing COM port applications may be used to transfer data via the USB to the CP2102N-based device without modifying the applica-
tion. See AN197: Serial Communications Guide for the CP210x for Example Code for Interfacing to a CP2102N using the Virtual COM
drivers.
Note: Because the CP2102N uses a USB-based communication interface, timing will not be controllable or guaranteed as it is with a
standard COM port. Full-speed USB operates on 1 ms frames, and the host schedules packets for each USB device where it can in the
1 ms frame. It is recommended to use large data transfers when reading and writing from the host to send data as quickly as possible.
4.4.2 USBXpress Drivers
The Silicon Labs USBXpress drivers provide an alternate solution for interfacing with CP2102N devices. No serial port protocol exper-
tise is required. Instead, a simple, high-level application program interface (API) is used to provide simpler CP210x connectivity and
functionality. The USBXpress for CP210x Development Kit includes Windows device drivers, Windows device driver installer and unin-
stallers, and a host interface function library (host API) provided in the form of a Windows Dynamic Link Library (DLL). The USBXpress
driver set is recommended for new products that also include new PC software. The USBXpress interface is described in AN169:
USBXpress® Programmer's Guide.
4.4.3 Customization and Certification
In addition to customizing the device as described in 4.5 Device Customization, the drivers can be also be customized. See AN220:
USB Driver Customization for more information on generating customized VCP and USBXpress drivers.
The default drivers that are shipped with the CP2102N are Microsoft WHQL (Windows Hardware Quality Labs) certified. The certifica-
tion means that the drivers have been tested by Microsoft and their latest operating systems will allow the drivers to be installed without
any warnings or errors. Some installations of Windows will prevent unsigned drivers from being installed at all. The customized drivers
that are generated using the AN220 software are not automatically certified. They must first go through the Microsoft Driver Reseller
Submission process. See AN807: Recertifying a Customized Windows HCK Driver Package for more information and contact Silicon
Labs support for assistance with this process.
silabs.com | Smart. Connected. Energy-friendly.
Rev. 1.0 | 20