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Photo of USB-I2C/IO Rev. B board(obsolete, please see the Rev. C1 board)
USB I2C/IO P.C.B. (Rev. B)

Product Summary:

The USB I2C/IO interface board provides a simple, "drop-in", solution for customers that need to connect hardware to a P.C.  The board provides 20 bits of user-configurable digital I/O, a 90Kbps I2C interface, and an 8 bit wide data bus for fast FIFO transfers.

Key Features

12Mbps USB interface to host P.C.
Cypress AN2131QC micro-controller.
20 bits of user configurable, digital I/O, via a commonly available, 34 pin connector.
90Kbps I2C interface, onboard 16KB I2C eeprom, 5 pin connector for attaching external I2C hardware.
USB Status LED, lights on enumeration, blinks to indicate USB traffic, off when suspended.
Break LED, useful when developing new firmware, also will be controllable via our API software
Small form factor (3.0" X 2.25") with 0.125" mounting holes in corners.
Downloadable board firmware, simplifies updates and allows for code customization.
Included API (applications programming interface) software gets your application up and running fast!


USB to I2C bridge for interfacing to a wide variety of I2C components.
USB to digital I/O bridge for interfacing to switches, LEDs, and other hardware.
USB to FIFO bridge for interfacing to FPGA's and other hardware.
Low cost USB development platform for AN2131QC (note: no address bus availability).
Test fixture interface.
Rapid prototyping interface.
Data Acquisition.


The full-speed USB interface provides your application hardware with a "Hot Plug and Play", 12Mbps, industry standard connection to your P.C. host.

Utilizes Cypress Semiconductors AN2131QC USB micro-controller.
Power configuration jumper allows board to be powered by USB or by external circuitry.
I2C power configuration jumper allow I2C bus to be powered by variety of sources.
Eeprom enable/disable jumper allows board to be used as an AN2131QC development platform for developing your own firmware.
Eeprom Write Protect jumper provides protection from accidental onboard eeprom erasure.

Click this link to view the schematic (or right click and choose "save" to download a copy of the pdf to your computer).


The included device driver, dll, and example application software make it easier than ever to access your application hardware from your P.C.

The software provides support for connection of multiple boards.  This makes the USB I2C/IO a great solution when multiple equipment instances are required (test fixtures, production equipment, instruments, etc.).  Each board can be uniquely identified by the application software via a serial number.

Click this link for drivers, dll, demo and example applications, and the API User's Guide pdf.

Design Reference Information

The following link will take you to a page with reference links for the components used on the board, sources for mating connectors, mounting hardware, etc. 

Click this link for design reference information, including mechanical information, mating connectors, etc..

Revision Notice:

The USB I2C/IO interface board has been revised several times. This web page provides information about the "Rev. B" version of the board.

For a comparison of the "Rev. B" and "Rev. A" boards, please click the following link: Comparison of Rev. A and Rev. B.

For information on the original "Rev. A" board, please click the following link: USB-I2C/IO (Rev. A).


The USB-I2C/IO Rev. B board is now obsolete and has been replaced with the USB-I2C/IO Rev. C1 board.

The boards are completely assembled and tested, and ready to plug in to your system (cable sold separately).



Send mail to webmaster@devasys.com with questions or comments about this web site.
Last modified: August 25, 2008