Category Archives: hacking

Photo by Melissa Roy

Arduino Workshop and Arduino Resources page

youdoit-arduino class

Had a full house at an Intro to Arduino Workshop at YouDoIt Electronics in Needham last night. Getting ready for this prompted me to start up an Arduino Resources page and update my Intro to Arduino Presentation (which, unfortunately I didn’t get to use due to technical difficulties…)

YouDoIt Electronics is a terrific local resource, carrying tons of Sparkfun and Adafruit products (as well as tons of mechanical and electrical parts, educational toys, AV equipment, you name it!) Thanks Melissa and John for sponsoring me!

Interactive Wall at the Duxbury Free Library

I was Maker in Residence at the Duxbury Free Library in August, where I worked with Teens and some adults to create an Interactive wall for display at the Library.

I met Teen Librarian Ellen Snoeyenobs at the first Make a Makerspace conference at the Artisan’s asylum several years ago, and we’ve been collaborating on bringing more maker activities to her library over the last 2 years. She has an excellent blog reflecting on their successes, failures, and tips :

She has her own excellent video here:

Lessons learned

  • Something for everyone. There are art activities for those who won’t go near tech stuff, and plenty of wiring and coding for the techies. Girls, boys, adults alike found something to do.
  • Drawing on skills learned in the past helps to get things done. We did one session on Arduino at the beginning, but in the end, those who already had Arduino experience ending up contributing most in that area.
  • Include a variety of activities. Kids who liked 3D printing and design did various bits to glue on, and use, including a spider that goes up and down. The 3Doodler was used a lot to add decorative elements, as well as enhance some of the 3D prints. And of course, Arduino brought it all to life.
  • Think Off the Wall. Ellen was originally inspired by an interactive wall she saw at MIT. The library, however, wasn’t too keen to be hacking into their existing walls. Ellen came up with the idea of a portable partition, and I helped select one (made of poly-carbonate) that we could drill. It had the additional advantage of being semi transparent, so we could mount our fireflies (addressable LEDs,) behind the wall.
  • Surprise learning. There were all sorts of bonus learnings, including how to scale a drawing up using a grid!


  • The library had previously received a grant that enabled them to buy a bunch of Spark Fun Inventors kits. We used velcro to attach the Redboards and their attached breadboards to the back of the wall.
  • We used a PIR motion sensor to trigger the bird moving, and cheap Chinese HC-SR04 ultrasound distance sensor to light up the peacock’s tail as you waked closer.
  • WS-2812 LED strips provided bling for both the peacock’s tail and the fireflies.
  • Birdsong was provided by a Sparkfun MP3 Shield
  • Movement was done with micro servos, and one continuous rotation servo from parallax.
  • The shifty eyed fox was implemented by a great design from Dampboot on Thingiverse

Come see it!

Our Grand Reveal of the Arduino Interactive Garden Wall will take place on
Thursday, September 10th at 4 p.m. on the Upper Level of the Duxbury Free Library.

We’re hoping some of the Teens as well as adults who had a hand in making it will talk about the experience.


MacGuyver Copter Part 2: Total Ghetto, Total Fail

Spoiler alert: in part 3, we finally succeed!

If you read the first post  you know that I was inspired by all the cheap replacement parts for the Syma X5. Also the motor mounts have all sorts of interesting attachment points, including a tube that fits a 3mm (who knew they were a standard size?) bamboo barbeque skewer. I’ve seen people bodge together quadcopters with “real” controllers but with crappy wooden frames, so I thought why not.

First I cut some skewers so the props were centered where they were in the original Syma X5. They were 9 inches center to center.


I taped it all together, with the controller in the middle. I didn’t have much hope, as  you can see the fit on the motor mounts isn’t tight, and I was afraid they would twist. I taped them the best I could but as you can see in the video it was a total fail.20150715_223808

One problem I noticed, was that I had mounted the controller board upside down. Doh! The purpose of the controller is to keep it upright!


Next I designed a 3D printed hub for the middle, secured with hot glue. I found some tiny screws (scavanged from many tear aparts!) and drove those through holes in the arms and through the bamboo skewers. This time it worked better but spun. I concluded that the bamboo was twisting with the motor torque. Probably true, but later I also discovered that I had the motors mounted in the wrong place.

Conclusions: I need a sturdier frame, but still need to keep the weight light (how light, well, I find out in part 3…)

From Blink to Bot: Introduction

JoebotJoe McDermot (leader of the Boston Robotics Meetup) discovered many members of the Boston Robotics Meetup had never scratch built a robot, so he sourced some cheap components from China and led a group build session. Joe did a fantastic job, keeping the price to $60, for a robot with 4 motors, Arduino clone controller,  3 ping sensors and IR control. (Joe’s a modest guy, but I call it Joebot)

After building it, a lot of the members had trouble with the programming, trouble I’ve seen when people attempt to do slightly more complex projects on the Arduino, after doing the basic Blink, and other examples.

In this series of posts, I will attempt to show how to coordinate several activities in an Arduino program. While the robot is an excellent challenge, the lessons here can be applied to any project where you have to “simultaneously” read sensors, control actuators, etc.


  • 4 DC gear motors with Wheels
  • Acrylic base
  • L9110s  BLUE motor control board (2 channel, 2 wire control per motor)
  • IR receiver
  • 2 – Ping type distance sensors
  • Arduino Nano V3 Clone
  • Breadboards, wires, etc.

One note of caution here, many of the Nano clones used counterfeit FTDI chips, and were bricked by the new windows driver. DCCDuino, is actually not an out and out copy and uses a different USB-Serial chip, and works well.

JoeBotLabledNext post we’ll work out how to handle motor control.


Free and Open Source Data Service from Sparkfun


Sparkfun launched a free cloud data service for your devices. It’s limited (rolling last 50MB) but also open source so if you want to roll your own you can do as much as you want!
This is an example of how doing a service and open source can benefit you. As they say

Our hope is that you buy a SparkFun widget to connect your next beehive.

It looks easy to use, and besides making it easy to put your own sensor data up, data from all other users is public, making it available to data scientists and hobbyists.

I’m looking forward to trying it out, and if I do I’ll share here!



NovaBooth – Improving the Open Source Photobooth

NoVa SnapAs you may have read here previously, we (the Wyolum Gang) created a photobooth for the Open Hardware Summit, for the purpose of customizing the e-paper badges we made for the conference attendees. This processed the pictures into a small black and white image for the e-paper badge, and saved it onto the badge’s micro-sd card.

I was headed to help out at the Northern Virginia Maker Faire, and thought it would be fun to update the photobooth to take full color pictures, upload them to the Internet and offer to email them to friends and relatives.

The email message and logo files are easy to add and customize.

For basic construction, visit the original post, but download the new software here:


The fabricate directory has the laser cut files, arduino for the AlaMode Program, and scripts for the python photobooth code.

Edit to customize the email subject and message. contains the authentication information for the google email and posting accounts. You’ll need to set up application specific passwords for this on your google account. You can use the same account, or separate.

Wireless keyboard, had to add a powered hub.


  • External powered hub was a pain.
  • Proto-screw shield was too heavy and lifted off
  • Some of the nuts came loose in travel.

Photobooth 1.5

To solve the first problem, I determined to replace the non-powered hub in the photobooth with a powered one.  I tried to add power to the unpowered hub, and this worked at first, but then took out the power supply and made the raspberry pi flakey too.

Scratch that, I ended up using a small belkin powered hub. I y-connected the power to it.
I noticed that  a convenient orientation put  4 ports right next to the edge,  so I cut a hole in the box to expose them.

Luckily AlaModes ship without shield headers installed, so I replaced the AlaMode and protoshield with an AlaMode that was directly soldered to the button, led-strip, power and ground.

I updated the AlaMode’s photobooth program directly from the photobooth. Apparently the new AlaMode’s pullups weren’t as strong, so I added a 5.7k pullup to the Button Pin.


Instant Party for Arduino Day!

You Do It Electronics in Needham asked me to help out with their Arduino Day celebration on Saturday March 29, and I wanted to make a nice Arduino demo that uses parts that they sell, relatively simple, and Fun! You Do It also sells DJ and disco equipment, so I thought what would be better than Arduino controlled Disco lights and Music?

Here are the Parts I chose:
Sparkfun Motion sensor (to trigger the Instant Party)
Sparkfun MP3 Shield
Sparkfun proto-screw Shield (to make it easy to hook up.)
Power Switch Tail – turn on the disco lights

You’ll also need a micro-sd card and some music. I chose some Creative Commons Techno from Soundcloud:

First, we need to find out what pins are in use in the MP3 Shield so we can figure out where to hook up the motion sensor and power switch tail.
The easiest way to do that is by looking at the schematic, or this page at Sparkfun:
MP3 Shield hookup

Digital Pins 5 and 10, and Analog Pins A0-5 are all free.

I used the analog lines because they are close to the power and ground pins for both the power switch tail and the PIR motion sensor.

Because the PIR output is open collector, I use the internal pullups on the Arduino.

Git the code here:


A Brief detour into Cryptocurrency

dogecoinI attended a meetup of HackBoston, run by Abby Fichtner (HackerChick) from the Harvard Innovation lab. Project 11’s Reed Sturtevant wanted to learn more about Cryptocurrency, so he started experimenting and shared the basics with us at the meetup.

Most people have heard of BitCoin, but Reed shared that it’s so hard to mine now, it’s very difficult to experiment without putting in real money. He found DogeCoin as a fun, and lighthearted alternative. Often used as a +1 or like tipping system for blogs and on social networks.

Pre-work was to set up wallets before the meeting, as they take time (about 5 hours) to synch with the network.

We each recieved 2000 dogecoin at the beginning of the meetup. Then we learned the basics of how to use addresses (essentially the destination of coin transfers. We transferred money to each other.

While doing this Reed went over the basics of cryptocurrency, which I won’t cover here, but the wikipedia article covers it pretty well.

We also created accounts at which lets you send DOGE via twitter. (feel free to tip @osbock)!

Intro to Mining

If you read the wikipedia article, you know that transactions are verified by a cloud of contributers performing cryptographic checks distributed across the Internet. “Miners” are rewarded both through the creation of new “coin” (which slows) and the distribution of transaction fees. Without special hardware, your chance of winning a race to solve the puzzle that is a cryptocurrency transaction is minimal, so mining pools were created to distribute the work and the reward.

We created accounts on the mining pool site, created workers (essentially addresses within the pool for your mining processes to communicate) and downloaded and configured mining software.

I recently got a nice “gaming” laptop from Lenovo, because it offered very good price performance, plus it has an Nvidia graphics card which I wanted for computer vision experiments.

Because Nvidia graphics cards contain many parallel processing cores, and Nvidia has released an API that allows their use for general purpose parallel computing, they are often employed for mining.

The Experiment

Following instructions from, I set up cudaminer (cuda is what Nvidia calls their processing cores) and another instance running the pooling cpu-miner to take advantage of the native cpu cores of my laptop’s i7.

Each mining process (cudaminer and pooling-cpu-miner) were configured to report to a “worker” setup at

I then mined overnight to determine:

  1. The kH/s (thousand’s of hash per second) capability of my laptop
  2. How much doge/hour I could mine
  3. Electricity cost of running the computer. (determined with a P3 Kill-a-watt)

Using an exchange rate, I converted into dollars to see if I could mine more doge than the electricity cost.

The Results

The cuda miner was reporting an average of around 80 kH/s and the cpu-miner around 54 kH/s

In 14.07 hours I mined 261.229 Doge for 18.57 Doge/hour, or $.0147/hour (at an exchange rate of .00079$/Doge.) Power usage was approximately 1.4 kWh, which I calculated to cost $.19.

Projecting out to a month, at  134 kH/s, I’d earn a whopping $.95 (and lose a lot of the computing bandwidth of my laptop!)

I could invest in a fancy graphics card and dedicate a computer, but I imagine it would cost even more electricity.  So, I would say  overall, a negative return on investment.

This apparently became the case for bitcoin as well, until people developed specialized hardware that gives a high H/s rate at low electricity usage, first using FPGA’s and then specialized ASICS (Application Specific IC’s). Doge uses a different Hash algorithm than Bitcoin, so you can’t use the now ubiquitous ASIC mining equipment optimized for the SHA 256 algorithm. There’s a new ASIC to be released soon that supports Doge’s (and litecoin, and others) Scrypt algorithm, and by extending my calculations, the cheapest of these devices ($119) would pay for itself in 3 or 4 months.

I’m going to try to get one to see. Of course, all these calculations are based on assumptions of stability (exchange rate, mining rate etc.) which are completely unreasonable. Still it’s fun to try!

Electrify Your Halloween! Making it Move!

In late September, I  led a workshop at the Duxbury Free library on making interactive Halloween displays, and more recently I set my project up on our porch for Halloween.  One of the most effective ways to make your front porch scary and immersive is to pay attention to sound, and to make things move.

The first part (making it scream) was documented in this post. This is about the movement part, creating a pop-up inflatable ghost, completely from scratch. It was very successful and popular!with the kids. Unfortunately I didn’t get any video, but I can cover the construction.

I like inflatables, and wanted to try making my own. One thing that made this really easy was a really cool product called Powerswitch Tail. This allows you to control an AC outlet from a digital signal. Its available from Adafruit and Makershed. It’s essentially a short extension cord with an opto-isolated relay in line. This eliminates any dangerous AC wiring with relays, and protects your Arduino and other circuits as well.

Next I needed to make the Ghost. I use white kitchen trashbags at home, and I took three of them, two laid end to end (with the end of one cut off.) I cut the third bag in in thirds and used the outside sections for arms. I used simple transparent packing tape to bond the edges.


A total of 3 bags (top and bottom, both arms)

I used one of those small vortex fans, and taped it around the output side.


Boo! Attached to the fan, and inflated.

Hook the powerswitch tail to a digital IO on an Arduino and you are good to go. As I mentioned in the last post, you can get the code on github here.


Open Hardware Summit Photobooth

As you know, my Wyolum buddies and I partnered up with SeeedStudios to make a really cool e-paper badge for the Open Hardware Summit which took place last week. We wanted some cool ways for people to customize their badges. Justin created a great simple program for converting images ( and I leveraged that software to create a photobooth.

photobooth (by Addie Wagenknecht)

Photo by Addie Wagenknect

My friend Michael Castor at Makershed built a cool tablet from the Raspberry Pi, and he told me about the nice 10.1″ LCD display and HDMI adapter he found from Chalk-elec.

I ordered one, and started figuring out how to put the whole thing together. I also got a big red button from Adafruit. I have been playing with the Raspberry Pi camera and it’s perfect for embedding in a project like this, even though the software is a bit primative at this point (no video for linux drivers, etc.) I used our own AlaMode to read the button and use one of our WS2811 arrays to do a visual countdown before taking the picture.

I’d never really designed anything for laser cutting, and this was my opportunity! I used Inkscape, with the T-slot extension written by Justin. I got the box cut at Einstein’s Workshop (a family oriented makerspace in Burlington, MA.)

Lasercut box

Next, I laid out the components. The trickiest parts were the LVDS cable (though it’s pretty generous) and the Raspberry Pi Camera flex cable.

One really sweet thing about the Chalk-elec hdmi adapter is that you power it, and there’s a USB power port to power the Pi.

Raspberry Pi and HDMI adapter


Attaching the LCD to the case is a little nerve wracking, as like most tablet screens, it’s intended to be glued in. I used 3M permanent mounting tape (really not tape but adhesive on a backing roll.) It’s really difficult to cut with scissors (it sticks to everything) I made the mistake of putting it on the bezel and trying to cut it with an X-acto knife. I scratched the paint on the bezel, but I managed to fix it with a sharpie.

The better approach turned out to attach it to the opening, and cut along the opening.


After trimming I added the LCD, and the USB panel mount jack.

I had to drill a few holes because I hadn’t completely planned ahead, for a jack for the switch box (used a 1/4 phone jack and plug) power, and the 16 pixel LED array.



I had planned for it to swivel on the sides from two carriage bolts with wing nuts. This meant making a stand, and I didn’t want it to be just a couple of 2×4’s. Also I was running out of time so I took Justin’s suggestion and made a tripod mount for it. More holes…. And a mending plate from the hardware store. Fortunately I have a set of cheap taps from Harbor Freight, so it was pretty simple to drill the plate and tap it (1/4-20) to accept a tripod mount.


Getting it hooked up with the short cables is a little tricky, but there’s room to get your hands in there:


I used a proto-screw shield to make it easier to hook up the button and LED leads. As you can also see, there’s a small usb hub inside too.

I booted it up:



and then hacked Justin’s Wifit program to take a picture:


Justin then created a more kiosk-y gui, and I ironed out a few things with the Arduino code for AlaMode. The gui checks to see if an sd card is mounted, and when it is, it sends an enable command to the button and prints on the screen “Press Button when ready”  The AlaMode then monitors for the button, and when pressed, sends the signal to take the picture and begins counting down on the LED strip. You can find the code in our github repository:

I tried also using the LED strip as a flash, and it worked but made sort of ghastly underlighting like a camp flashlight! So I took some cheap chinese led strip I had around (about $12 for 5 meters) and made a light panel:


And the finished product:


And on the badge:

IMAG1729I’m thinking of modifying the code to upload higher res pics to the Internet with an imprint, or printing them on a portable printer I picked up at a yard sale!

By the way, I left the Raspberry Pi’s wifi dongle attached, as it made it much easier to debug with SSH from my laptop. That said, I did also plug another hub into the one exposed port to use a keyboard and mouse (even though the touch screen does work!) If I had to do it over again, I might bring at least one more port out for other devices.

You’ll notice in the first picture, the Wyolum Logo across the top. Elizabeth Shaw cut that for me and delivered it the morning of the OHS, and it fit perfectly!