Node.js on the Arduino Yún

Recently, Federico Fissore added node.js to the package repository for the Arduino Yún. Here’s how you get node to communicate with the Arduino processor on the Yún via the Bridge library.

To do this, you’ll need an Arduino Yún, a microSD card, a microUSB cable and a wifi connection. You should be familiar with the basics of the Arduino Yún and node.js in order to get the most out of this post.

All of the code for this post can be found on my GitHub repository.

Continue reading “Node.js on the Arduino Yún”

A Few Good Reasons Why Peter Knight Rocks

Peter Knight works with Massimo and Alex and co. at He’s written some great AVR code, which is useful in Arduino.  For example:

Secret Thermometer takes advantage of the ATMega’s internal thermometer. Turns your ‘328-based Arduino into a thermometer with no extra parts.

Secret Voltmeter same idea, but this reads the internal analog-to-digital converter to tell you the Arduino’s supply voltage. Also works on the ATMega168.

He’s also done Cantarino, a speech synthesis engine; Auduino, a granular sound synthesis engine; a DMX library; and more.  Check them all out at the code repository.

Multiple time stamp checks on a microcontroller

Sometimes you need to manage multiple events with a microcontroller that all require different timing.  For example, you might want to control a servomotor (which requires a 20 millisecond delay), blink an LED once a second, and read some sensors (which should be read as frequently as possible.  One way to handle this is to keep track of a time stamp for each event.  You constantly read the millis() and if enough time has elapsed since the last time a particular event occured, you do it again.

Continue reading “Multiple time stamp checks on a microcontroller”

Using an Accelerometer to Sense Which Way Is Up

ITP just got some nifty flat panel mounts that can rotate 360 degrees. They’re very easy to move, it takes only one hand. When I saw them, I thought, “what good is a rotating mount if the content on the screen can’t rotate too?” So I came up with a little system to sense the screen’s rotation. Here’s how to turn those screens into a very big iPhone. Thanks to Michael Dory for his help in coding this and Dan O’Sullivan for the final clue.

The screens have a mac mini mounted on the back to display digital content. I added an Arduino with an accelerometer mounted on it to sense the angle of the screen’s rotation, then sent that data into Processing.  This example doesn’t do much, but the code can be re-used for any Processing application that needs to know the screen’s rotation.

Rory Nugent modified my existing code and made it much better.  I’ve incorporated his changes here, thanks Rory.

Continue reading “Using an Accelerometer to Sense Which Way Is Up”

Sensorbase datalogger is an open data repository run by the Center for Embedded Networked Sensing at UCLA. It’s a database of sensor databases. You can upload datasets to it, and you can browse other datasets as well. If you’ve never set up a database before but are interested in logging sensor data, it’s a good tool to get started. If you know what you’re doing already and you need to log a lot of sensor data, or compare it to similar work from others, it’s a convenient tool.

Since I like working with sensors and microcontrollers connected directly to the Internet, I thought it would be useful to be able to put data directly into Sensorbase from sensors connected to a microcontroller, without a personal computer in between.

Continue reading “Sensorbase datalogger”