I like to take things apart. Sometimes they work when I'm done. I've been a member of NYC Resistor since 2010 and you can see more of my projects at

Dec 022014

Want to drive more LEDs with fewer IO pins? Then you might be interested in the Charlieplexing technique. I’ve written an example sketch can drive six LEDs each with 8-bit PWM using the three IO pins on the Adafruit GEMA microcontroller and is a fairly easy sewable LED sequin project since there are no crossed wires when it is stitched with conductive thread. Enjoy the short video of it in action below and read on for more details…

Nov 162014

Are you worried that you’re not paranoid enough about your communications security and want to improve your OpSec? Edward Snowden says to trust in encryption, but you still need to worry about the systems that run it:

Encryption works. Properly implemented strong crypto systems are one of the few things that you can rely on. Unfortunately, endpoint security is so terrifically weak that NSA can frequently find ways around it.

One step towards going “Full-Snowden” is with hardware storage of your PGP secret keys! The Yubikey Neo and Neo-N USB tokens are a neat (and not too expensive) way to keep the secret part of your RSA2048 keys locked in a hardware device rather than stored as a file on your harddrive. The hardware tokens are compatible with the OpenPGP card protocol, which recent versions of gnupg support out-of-the-box. All of the public-key cryptography happens inside the tamper-proof device, so your secret key is never decrypted in the memory nor stored on disk of your machine.

Since setting up the key pairs and transferring the secret ones to the device can be tricky the first time, I wrote a brief guide to configuring Yubikeys as OpenPGP crypto-hardware tokens. They integrate nicely with Apple’s (or mutt with gpg-agent), so there is one less excuse for not protecting your email.

Hack Holyoke

 Uncategorized  No Responses »
Nov 102014

Hardware checkout at Hack Holyoke
Last Friday was the Hack Holyoke 24-hour embedded systems hackathon, held at Mt Holyoke College. Of the 200 participants, well over half were women from the Seven Sisters schools and many were attending their first hackathon.

Hack Holyoke dance party
One of the distinguishing features of this hackathon was a 2am dance party! Every event should include one.

You can read @HackHolyoke twitter stream and read on for some photos of a few of the teams.

Continue reading »

Sep 042014

Hopper Interactive Disassembly
Want to get started with reverse engineering on i386, x86-64 or ARM systems? The Hopper disassembler makes it easy! Or at least easier to understand what is going on in binaries, firmware dumps and other random executables that you might encounter.

This four hour class is taught by Trammell Hudson, the original author of the Magic Lantern firmware for Canon DSLR cameras, and will cover initial exploration of files, annotating functions, discovering common patterns and using the control-flow graph / pseudo-code generator to understand what the assembly is doing.

Experience with programming, but not necessarily assembly language, is necessary, as is a Mac or Linux laptop. Buy your tickets here!

Solder paste

 Uncategorized  1 Response »
Jul 142014

MOSFET level shifters
If you find yourself soldering tiny SMD packages, like these dual MOSFETs, you might pull out the microscope and get to see the solder paste for what it really is:
Solder paste under the microscope
So many tiny balls of solder! And as all of the microscopic spheres melt, surface tension pulls the blob onto the pads in the most amazing way.

Jun 032014

Mega Mario

Megascroller is the 512×64, 32-sided upgrade to Octoscroller, which was the eight sided RGB update to the venerable six-sided red LED Hexascroller. Megascroller is featured as one of the art pieces at the upcoming Interactive Show — on the giant cylinder you can play different video games in the round. Unlike normal side-scrollers, you have to move sideways to keep up with the onscreen characters. Here’s a video as we play-test Mario (source code) and discuss some tweaks to the game to enhance the fun (there is some interaction with the camera shutter that makes artifacts in the movie).

Buy your tickets now! and come see Megascroller plus lots of other fun interactive art at the 2014 Interactive Show. The doors open this Saturday at 8pm! The show is over and was great fun! Here’s a video of Mario being played in the round sometime late last night:


 Uncategorized  2 Responses »
Jun 022014

Two weeks ago we salvaged two PDP-11/34 minicomputers, VT1xx terminals and assorted parts. Since then we’ve spent some quality time in the 1970s, cleaning Unibus contacts, reseating cards and replacing bad capacitors in the VT100 analog boards. Both of the CPUs start up fine and we’ve been able to read data from all of the RK05 and RL01 drive units. Still haven’t touched the tape drives, so no digitized monkey brains yet. Instead, here is a video of running Colossal Cave Adventure compiled from the original FORTRAN IV sources under RT-11v4 on our PDP-11/34:

 Posted by at 9:31 pm