Dad Finder


This Ikea clock was modified to display my location for my family at home. It is nice that they can check up on me without checking online. The kids are especially enjoying it.

I use 5 different geofences in an iOS app, monitoring entrances and exits for key points on my daily commute (and the bay area as a whole). The app reports the triggers to a Google App Engine app. The minimal time allowed by iOS is enough to get the call through to the server. GAE then passes the events onto the clock via the iDigi web service.

Inside the clock, I use a Fio and Xbee radio paired to my ConnectPort x2. iDigi is able to push messages through the ConnectPort to the Xbee and update my status.

Original project date: Dec, 2012.

External switch and charger for LilyPad LiPower

This Lilypad LiPower is pretty cool.

It’s basic role is to convert a 3.5v Lythium Polimer battery to 5v for Powering an Arduino micro-controller. That is done with the + and – pins in the bottom half of my photo.

Additionally it has a connection for charging the battery without disconnecting it or removing it from the project. That is done with the (partially obscured) c and – pins toward the top of my photo.

Also toward the top is a switch that turns the power to the Arduino on and off. The battery charges regardless of this switches position. This LiPower is inside the project I am working on, so I’ve added an external switch (SPST) by connecting it to two of the pins of the on-board switch.

So far this set-up is working fine. I can plug a charger externally and switch the Arduino’s power while the battery is charging or not.

UPDATE: Since writing this, I have added a connection between the B pin on the Lipower board to an analog pin on the Arduino. By doing this I can now read the voltage of the battery and light a warning LED when it gets low. I found that the Lipower outputs 5v until the battery voltage drops below about 2.9v. At that point the Lipower switches things off to protect the battery. 

Arduino, Bluetooth and Flash

Arduino, Bluetooth and Flash

I spent more time than I would have liked trying to get a basic Bluetooth connection between my Arduino and Flash applications. At first, I could not get anything working, then I switched to SoftwareSerial and could only send data to Flash (or coolTerm). Finally, I saw the note about not all pins on the Leaonardo supporting RX and I got it all working.

I’ve posted my code on GitHub, perhaps it will save you some time. I think I have removed all my dead end trials and everything that is included is necissary for it to work.

Light Racer


My kids love arcades where you can win tickets and buy prizes. Some of their favorite ways to win tickets are the various games with speeding lights zooming around a circle with a big button that stops the action and dispenses tickets. The ultimate goal is the jackpot light, which of course is bordered by the lowest value lights… timing is everything.

This year, as a prelude to our annual pilgrimage to the Santa Cruz Boardwalk, we designed and built training boxes. The guts (pictured above), include an Arduino Uno, 16 LEDs, a momentary switch and a 9v battery. Supporting systems include a potentiometer, assorted resistors and a very satisfying on-off switch. Everything is housed inside an aluminum project box that looks pretty good and relatively easy to work (except with is comes to anchoring anything that is not surface mounted).

Below is a video that shows the assembled boxes in action. The game has 16 different speed settings (controlled by the potentiometer) and 16 levels. Each time you stop the light on the final LED, you advance a level. If you miss that last spot three times in a row, you get knocked back a level. Finish all 16 levels and you get a fun little bonus.

Building your own toys

The kids really enjoyed designing and building their own electronic toy.

At ages 7 and 9, they are getting a good sense of what makes some of their other toys tick and are getting exposed to the benefits of iterative prototyping. Based on their feedback to the first version of the boxes, we replaced a micro pot on the inside of the box with the beefy, surface mounted knob next to the on-off switch in this version.

They also love the idea that in a couple months we can tear the whole thing down and build a different toy. We already have plans for some toys connect in a wireless mesh network for multiplayer games.

Connected Personal Objects: Getting Intimate with the Internet of Things

Last week, Guthrie Dolin and I presented at the Planning-ness 2012 conference. The conference was great, and I love it’s theme, “Get Excited and Make Things.”

The standard format for a session is present on a topic and then run a workshop in which conference participants make something to present back to the group.

In our session we provide an overview of the Internet of Things before going into detail about the potential of connected objects to encourage specific behaviors. We break down the components of an IoT ecosystem and discuss how they can be used to collect data and drive insights and change.

Following the presentation, the assignment was to use the framework and design a physical product and service around a personal object or situation. We provided a few catalysts and blank worksheets to help get people going. The results were great and we’ve posted each group’s worksheets on slideshare as well.

All-in-all, a great expreience and a ton of fun. Thanks to everyone who turned out to learn about the Internet of Things.


This year’s eggs were designed using Nodebox and Inkscape.

Charlie worked mostly in Nodebox. It’s patch-based programming was right at his level and copy, rotate and wiggle all got a lot of action.

Wyatt found inspiration in Minecraft and we worked together to write a letter writing script in Python to print out an wiki entry on egg. Then he created a vector version of the pixelated egg in Inkscape.

The video below shows some highlights from production.

Testing OpenCV and api offers a robust API for facial recognition. In short, you send it an image and it will process that image finding faces within it and return information about what it finds. That information can be used to locate features of the face as well as other characteristics of the face. These other characteristics include the age and gender as well as the presence of glasses or a smile.

As a test, I built a standalone app that sends faces appearing in an attached web cam to the API for analysis.

First, I built a basic Flash AIR application to upload images to the API. For this I used Jean Nawratil’s Flash ActionScript 3.0 Client Library and sent images each time a key was pressed on the keyboard. The only modification I made to Jean’s library was to add a parameter to the POST made to the API. The parameter (attributes=all) tells the API to return additional characteristics.

With this in place I integrated OpenCV to locally detect when a face is present in the frame. This way, I could automatically send images to the API, but only those with something for to find — reducing the load on their servers (and my rate limit).

I’ve used an AS3 implementation of OpenCV in the past, but the performance was terrible. For this project, I used Wouter Verweirder’s AIR Native Extension which offloads the work to native code. It is very responsive.

Using a standard face cascade, OpenCV recognizes faces and indicates approximately where they are in the frame. Based on this detection, my app sends a copy of the image to for further analysis. The round trip to the API is quick and generally takes less than a second, two at the most. I added a timer to the app to further limit how often I send off an image to the API.

Below are some captures from this basic proof of concept. Below each are the characteristics detected by the API.

Testing OpenCV and apidavidbliss-2_copy-1Testing OpenCV and api

In addition to basic face detection, the API allows you to identify and tag people based on images you use to train the algorithm and/or images in a Facebook account. For more information about the API and what it can do, be sure to check out their online demo.