Make a sensor interface for your computer for under a buck! Update 6/9/08: After exploring several avenues I've concluded there is no practical manner of implementing this technique in Microsoft Windows. This is not petty OS bashing, I've really busted a nut trying! Windows users needing I2C capabilities are best served by existing USB-based solutions.

The documentation provided by FTDI is very complete, and is not duplicated here. Before using the USB-I2C, you will need to install FTDI's Virtual COM Port (VCP) Drivers. These drivers appear to the system as an extra Com Port ( in addition to any existing hardware Com Ports ). Application software accesses the USB. I2C get using libftdi and FT4232 chip connected to USB. Note that this utility will open the first FT4232 chip found. . Written by Ori Idan, Helicon technologies LTD. (ori@helicontech.co.il). . i2cget is free software: you can redistribute it and/or modify it. under the terms of the GNU General Public License as published. Comm Operator is a professional communication software for Serial Port, TCP/IP, UDP, I2C, HTTP, and FTDI. Lampduino is a computer-controlled free-standing floor lamp, comprised of an 8x8 RGB LED matrix. The lamp stands 45' high and 18' wide.

Update 5/24/08: Linux support has been added, as well as sample code for the Nintendo Wii Nunchuk controller and the BlinkM 'smart LED.' See the README.txt file included with the source code for directions on compiling and setup on Linux. I2C (short for Inter-Integrated Circuit) is a two-wire serial bus typically used in computers for low-level communication between internal components.

I2C is also popular in robotics. All manner of sensors and actuators are available in an I2C-compatible form: ultrasonic rangefinders, sensors for acceleration, tilt, temperature and pressure, servo controllers, and bus expanders that provide additional general-purpose (GPIO) lines. Most modern microcontrollers (Atmel, Microchip PIC, etc.) have support for I2C built right in. But the processing power available on microcontrollers is limited, and software development - with specialized cross-compilers and programming environments - can sometimes be a chore. With laptops and single-board computers becoming ever smaller and more affordable, it's increasingly common to see these systems used directly in robotics and electronics projects. This provides ample power for new capabilities such as vision processing and more sophisticated A.I., and it greatly expands the scope of available development tools and languages.but it also presents a new problem: interfacing these 'regular' systems to peripherals is typically done through mainstream consumer-grade ports such as USB; there's no externally-available 'I2C port' we can just tap into to make use of our sensors.or is there?

Step 1: Existing Options. One way of connecting I2C devices to an ordinary desktop or laptop computer is through a USB-to-I2C adapter. There are at least a dozen such options out there, ranging from do-it-yourself kits with open source software, to sophisticated commercial units with every bell and whistle. Download Tokyo Game Convention Seattle. One downside to the USB-to-I2C approach is cost. A full-featured commercial model can cost $250 or more. Even the 'free' homebrew alternatives assume a collection of parts and a prior investment in a microcontroller programmer and the related knowledge to make use of it. Another downside is the relative scarcity of driver support outside the popular Windows fold.

Few of these devices work natively on Macintosh or Linux computers. Step 2: DDC Is I2C. When I said in the introduction that there's no external I2C port on most computers, I lied. Turns out there is, and it's been there all along for nearly a decade now, mostly sitting dormant.

Most modern graphics cards and monitors have support for something called Display Data Channel (DDC), a communication link within a video cable that allows the computer and display to negotiate mutually compatible resolutions and permit software control of monitor functions normally accessed with physical buttons on the display. DDC is, in fact, simply an implementation of an I2C bus with a few established rules. By tapping into this connection between the computer and monitor (or making use of the DDC lines on an spare unused video port, such as the external monitor connection on a laptop), one can interface with some I2C devices at virtually no expense, bypassing the usual need for an adapter device entirely. All we need to physically access this I2C bus is a hacked-up video cable. Step 3: Dissecting the Cable. Four wires are needed for our I2C interface: +5V power, ground, serial data and serial clock.

Pinouts for the various types of video ports can be found on. Remember if using a VGA cable to find one with the full complement of pins; some only include a subset. Cutting back the insulation and shielding from the outside of the cable, you'll likely find two groups of wires within. Thicker wires, or bundles of wires wrapped in additional shielding, usually carry the video signal.