Debugging I²C with Hardware

Alasdair Allan
2 min readDec 11, 2018


The Inter-integrated Circuit (I²C) communication standard is widely used throughout the maker community. It allows multiple “slave” devices to communicate with one, or sometimes more, “master” devices. It’s a short range standard, intended to be used inside a single piece of hardware, to enable reliable communications between the micro-processor and other hardware like sensors. Unfortunately the I²C protocol can be somewhat tricky to debug since modern desktop computers just don’t speak it. Which is where the I²CDriver board might prove useful.

The I²CDriver driving three 8x8 LED modules. (📷: James Bowman)

Designed to sit in between your laptop and prototype I²C devices, the board lets you access and control I²C “slave” devices directly from your desktop PC — which should be helpful when prototyping, and calibrating, sensors. It works with Windows, Mac, and Linux.

“When an I²CDriver is connected to an existing I²C bus, it ‘snoops’ the traffic and displays it on the screen. This provides an excellent tool for debugging I²C issues, because you can listen in on the conversation as it happens…as well a live decode of the traffic, the built in display shows a heat map of all active network nodes. So in an I²C network with multiple devices, you can see at a glance which ones are the most active.”

The I²CDriver driving a test board with three modules. (📷: James Bowman)

The I²CDriver is the second crowdfunded effort by James Bowman, and Excamera Labs. The first was the SPIDriver—an SPI adaptor/multi-tool which has just shipped to backers after raising on CrowdSupply earlier in the year. Bowman was also behind the Gameduino and the J1 Forth Core for FPGA. Implemented in just 200 lines of Verilog, a 50 MHz J1 CPU was used as a co-processor for the Gameduino.

The I²CDriver is raising now on CrowdSupply. (📹: James Bowman)

If you want to pick up your own I²C driver hardware, the project is already over-funded and is currently raising on CrowdSupply with 30 days left.

An I²CDriver board from the first batch, with three sets of hookup jumpers, will cost $29, with free shipping inside the United States, and an additional $12 for world wide shipping. Other pledge levels, which include I²C breakout sensor and actuator modules, are available. Orders placed now should ship towards the start of March next year.



Alasdair Allan

Scientist, Author, Hacker, Maker, and Journalist.