Archive for the ‘ Software ’ Category

Blink(1) + Google Latitude = “Where’s Daddy?”

A while back, I backed a Kickstarter: Blink(1) – The USB RGB LED. In a world of next-day instant-gratification deliveries, it’s always a pleasant surprise when something you totally forgot about ordering turns up.

It fits neatly into the spare USB port under an Apple keyboard.

2012-12-13 20.18.07

Time for a Pomodoro hack – make something useful in 25 minutes. No time for over-engineering – hack fast!

After a long delay on the train yesterday and my kids calling up to ask if I was nearly home yet, I knew exactly what I wanted to build…

The “where’s daddy?” indicator:

  • Blue -> home (or near home)
  • Red -> work
  • Green -> commuting.



  • Minutes 0-3: Unpack Blink(1), download command line tool, and test it out. Looks good.
  • Minutes 4-14: Read the API docs for Google Latitude. Tried really hard to get authentication working but realized I was burning time. Arrrg, the pressure – this is taking too long! Aborted and looked for a quicker way.
  • Minutes 15-18: Found a quicker, hackier way to get Google Latitude data. Worked!
  • Minutes 19-22: Hacked up a quick Python script to poll Google Latitude, and convert the coordinates to a value from 0.0 to 1.0 where 0.0 is home, 1.0 is work and 0.5 would be half way between.
  • Minutes 23-25: Based on the number, call the blink1-tool command setting the color to indicate my location.

2012-12-13 20.18.18 2012-12-13 20.18.29

Here’s the code:

(Ok, I cheated a little – I spent another Pomodoro cleaning up the code, adding comments, etc and another 2 Pomodoros writing this blog post).

Resistor color codes – now in DuckDuckGo search results

Remember a few weeks back I announced, a no-frills resistor color code calculator?

Welllll, if you happen to be a user of DuckDuckGo, it’s now even easier. See the resistor colors directly in your search results!



Try it out at DuckDuckGo.

And thanks to DuckDuckGo for making it so easy to extend your search engine.
Here’s the code.

I never have a resistor color chart handy when I need one. So I built a little web-app. Fast loading, simple, mobile friendly, and to the point.

Updated website for Smoothie Charts

Smoothie Charts has a new website. Rather than add to it, I ended up taking stuff out. It’s simple and to the point. It also works well on mobile / tablets.


Driving 16 LEDs from a Raspberry Pi, using a shift register

Just received a Raspberry Pi.

Thought it would be fun to try and hook the GPIO pins up to a shift register. This would allow a few pins to drive many more.


A 3D WebGL GCode viewer, for understanding 3D printers

Towards the end of 2011, I built a 3D printer (RepRap Prusa Mendel). It took 6 weeks of evenings and weekends.

Here it is, printing an Octocat I found on Thingiverse:




To help understand the model better, I created a WebGL based tool that can view GCode (the set of movement instructions sent to the printer).


It’s built on MrDoob’s (excellent) three.js library, which brings 3D programming to mortals.

If you work with .gcode files, try it out:

Code is over on GitHub:

And here’s a full set of photos journaling the building of the printer, and some things I’ve printed with it:

MSP430 + ShiftBrite

I like the Texas Instrument MSP430 microcontroller. It’s cheap, low-powered and has tons of features. You can get a complete development board, with embedded debugger, software and 2 controllers for $4.30!

I also like the macetech ShiftBrite RGB LED modules. Makes it easy to add a bit of color to electronics projects.

So here’s a library that makes it easy to control a ShiftBrite from an MSP430: