USB CDC/ACM Class Driver for Windows CE and Mobile

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USB CDC/ACM Class Driver for Windows CE and Mobile



Thesycon’s USB CDC/ACM device driver provides a serial port emulation on Windows CE by implementing a serial link emulation protocol on USB.

The driver exposes a Win32-compatible COM port. The driver works with devices that are compliant to the Communication Device Class (CDC) specification, subclass Abstract Control Model (ACM). However, the driver supports three different USB protocol types which are described in more detail below.

The driver runs on USB Host controllers that support the Microsoft USB Host Driver Interface (USBDI).

Supported USB Protocols

CDC/ACM Compliant Protocol

The device needs to implement the Abstract Control Model (ACM) subclass defined in the USB Communication Device Class (CDC) specification. This protocol requires two USB interfaces, a data interface which consists of two endpoints (bulk in + bulk out) and a control interface which consists of one interrupt in endpoint. Furthermore, on EP0, the device needs to implement the class-specific requests defined by the CDC specification. Because this USB protocol is compliant to the CDC/ACM standard on some operating systems (e.g. Linux, MacOS), the device can work with in-box drivers.

Reduced CDC/ACM Protocol

This mode uses the CDC data interface (bulk in + bulk out endpoint) only. No control interface (interrupt in endpoint) is required. The device needs to implement the CDC class-specific requests. This means it is still possible to support baud rate settings and serial control/status lines. This mode is useful if the number of available endpoints is limited by hardware restrictions. However, as the protocol is proprietary a specific device driver is required for every operating system platform to be supported by the device. In the future, Thesycon will provide further device classes such as Mass Storage device class.

Bulk-only Protocol

The device implements the data interface (bulk in + bulk out endpoint) only. The device does not provide an additional control interface and does not need to implement any class-specific requests on EP0. Because bulk transfer mode provides flow control there is no need to support serial control/status lines. The advantage of the bulk-only protocol is that the implementation efforts on the device side are reduced to a minimum. However, because the protocol is proprietary a specific device driver is required for every operating system platform to be supported by the device.

USB CDC/ACM Class Driver Features

Supported Platforms  
Windows Mobile 6.5
Windows Mobile 6.1
Windows Mobile 6.0
Windows Mobile 5.0
Windows Embedded Compact 2013
Windows Embedded Compact 7 (WEC7)
Windows Embedded Automotive 7
Windows CE 6.0, Windows Embedded CE
Windows CE 5.0


A similar driver is also available for Windows 10.

Free Demo, Licensing conditions & Prices

Current version: 1.59

To receive a free demo, please fill out the contact form.


The demo version of the driver stops working after 2 hours. To reset the demo timer, the driver needs to be unloaded and loaded again. This can be done by rebooting the platform or disconnect and reconnect all USB devices were loaded for.


USB Vendor and Product ID

For each USB device model an official USB vendor ID (VID) is required. Vendor IDs must be unique and will be assigned by the USB Implementers Forum ( Registration fees will be charged.


Thesycon owns a USB vendor ID and offers a subset of product IDs (PID) to device vendors. For customers who have licensed USB software from Thesycon this service is free of charge.

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