PORTS Forum

Ports and Interfaces => USB => Topic started by: WestfW on November 01, 2014, 10:01:45 pm

Title: CDC vs Custom Drivers for USB/Serial
Post by: WestfW on November 01, 2014, 10:01:45 pm

Are there known deficiencies/bugs/problems/etc in using the USB Standard CDC/ACM definition (or standard drivers) for USB/Serial converters?  I've been wondering why so many of the commercial chips (Prolific, FTDI, WCH, CP2102, etc) have propriertary protocols and drivers...

Title: Re: CDC vs Custom Drivers for USB/Serial
Post by: Jan Axelson on November 01, 2014, 10:51:45 pm

For CDC, you need to provide an INF with the device's Vendor ID and Product ID, digitally signed for Windows 8.

Devices that use FTDI and similar can use the chip vendor's INF file.

The CDC class doesn't define a way for the host to directly read an RS-232 CTS signal.

The vendor drivers likely have better performance/faster.

The downside is the need for a separate chip, while with CDC you can use just about any general-purpose microcontroller with a USB device port.