Latest Posts

Reading digital calipers with an Arduino

What do you use to measure sizes accurately? A pair of calipers of course! And what would you use if you need accurate measurements as input for a computer program? Again, a pair of calipers. Most digital calipers have a hidden port that outputs measurement data. In this post I will show how to interface digital calipers to an Arduino.

Digital calipers
A pair of digital calipers. There is a small data connector behind the lid.

This is the pair of calipers I will be using. Behind the black lid at the top are solder pads carrying – from left to right – ground, data, clock and +1.5V. This should be the same for most calipers, although it’s best to measure using an oscilloscope or multimeter to be sure.

HackersNL #7

1 Minute By Renett Stowe

Thursday 29 March 2012 I will be talking about Nut & Bolt and Stripe at HackersNL #7 in Utrecht. I’ll be giving an exclusive behind-the-scenes look on what running a one-man interaction design studio is all about. You’ll see prototypes, failed experiments and the technologies behind some of my interactive projects.

Stripe PCB v0.1

The PCB is the electronic backbone for an interactive product. It connects vital pieces to each other. The Stripe PCB has to perform several functions: power the Carambola, connect Carambola to the LED strip, provide a USB port for future extensions and house connectors for programming and troubleshooting.

Stripe PCB layout

Scripting Carambola with Lua

A piece of Lua script
Earlier I told you about Carambola, the small and inexpensive embedded Linux board, and how it’s going to be the brains of the Stripe internet-enabled linear clock. To make an interactive product do what you want you need software to tell it what to do. There are many programming and scripting languages around, so how do you pick the right one? In this blog post I’ll show you how I settled for Lua as the scripting language of choice for Stripe.

Stripe prototype

The last couple of weeks I have spent a lot of time working on Stripe. Designing an interactive product means overcoming many technical hurdles: getting the electronic components to work together, writing software, tweaking the mechanical design. All this hard work is starting to pay of, as today I have something to show you: the Stripe prototype!

Stripe Prototype
No meetings today. In the evening dinner with friends and a concert. What a day!


Connecting an RGB LED strip to Carambola

Measuring SPI signals with the scope

Interfacing RGB LED strips to an Arduino is easy: it’s been done many times so often it’s a matter of downloading the correct code library and you are ready to go. These plug-and-play code libraries do not exist for Carambola, but for Stripe I need one. Today, I will show you how I hooked up the hardware and created the software for an LPD8806 RGB LED strip connected directly to the Carambola.


8 Oscilloscopes < €400

An oscilloscope is an essential tool when trying to understand what is going on inside your electronics. It is an expensive piece of kit: even a simple model costs several hundreds of euros/dollars. While it is possible to buy great second-hand analog oscilloscopes for a lot less, they are very bulky and don’t have the digital storage capabilities of modern oscilloscopes. In this post I’ll list the sub-€400 digital storage oscilloscopes I evaluated before purchasing one for Nut & Bolt.

Stripe: a quick illustration

Stripe (you know, the linear clock) is going to have a wooden faceplate. I like wood – it looks good, has good mechanical properties and is easy to work with. Yesterday, I had a nice chat with Dana Cannam. He designs beautiful products that employ wood in an innovative manner and his Clamp LED lamp has just gone into production.

After talking to him I slightly changed the design of Stripe:

Stripe illustration
Stripe linear LED clock.

The wooden faceplate is just over a meter long and has 32 holes for the RGB LEDs. The control box houses the LED controller. I’ll be off to Protospace, the local FabLab, soon to mill the faceplate out of beech and oak. Let me know what you think!