DIY LED Strip Controller

On a whim I decided to add LED lighting to my desk hutch. I already had a reel of LED strips but nothing to control them. As I wanted to build a controller that afternoon, I constructed it from parts which could be purchased locally. The controller I made has an on/off switch and two knobs: one to control the brightness and the other to control the color of the lights. Here is how I built it!

This project required the following parts: two 10K ohm potentiometers with knobs, an on/off switch, a project box, a 5 volt power supply, a power jack, some wire, and a small Arduino compatible microcontroller. RadioShack sells the Arduino Micro, but I used a Teensy 2.0 I had on hand as it is a much cheaper alternative. Of course, you also need some programmable LED strips. I used some 5 volt WS2812B LED strips (similar to Adafruit’s NeoPixel strips). It’s also useful but not required to have some connectors for the LED strips so that they can be detached from the controller. I used some JST connectors from my project stash.

The first step is to make holes in the project box. I did this with my trusty Dremel. Drill five holes: two for the potentiometers, one for the power switch, one for the power jack and a one for where the LED strip wires will enter the project box. Once the box is drilled out, place the power switch, potentiometers and power jack into the project box. Solder the power wires to the components.

IMG_9702Next, I assembled the LED strips. If you are adding connectors to the LED strips, solder those on to the strips. If you’re connecting multiple strips, be sure that you bundle the wires together properly. I’ve found that using colored wire or marking wires with different colors of tape makes it easier to keep everything straight.

IMG_9722Next, solder the potentiometers and LED strips. Mark the data lines for the LED strip and the potentiometers so you know which wire corresponds to a given component. It makes coding the microcontroller easier.

IMG_9761Next, solder the microcontroller.  Keep track of the pins and their corresponding data lines. When soldering the potentiomenter to the microcontroller, make sure to connect the potentiometer data wire to pins that can support the analogRead function. These pins generally begin with the letter ‘A’.

IMG_9767Now it’s time to program the microcontroller. The simple code can be found here. Update the code to reflect the length of your LED strip and the pins that correspond to your components. Be sure to test everything!

IMG_9771Once you’ve verified that everything works, tape up any solder joints so that there are no shorts. Close up the box and you’re done!

IMG_9772

 

Knitting

photo 2I recently taught myself how to knit. I was interested in the mechanics of knitting, especially how it’s possible to weave string into cloth with just a few simple tools and techniques. It was also appealing because it’s something that can be done in small sessions rather than requiring long spans of continuous attention. Furthermore, knitting is a skill that allows you to make really cool things.

Knitting during a flight delay
Knitting during a flight delay

To get started, I picked up an awesome introductory knitting book, Stitch N’ Bitch. The friendly folks at Knitty City also helped me pick up some needles (size 10) and yarn that were suitable for a beginner.

ScarfMy first project was this simple ribbed scarf. Admittedly, it took me a long time to figure out the purl stitch, but I finally had some success with the English method of knitting. At the beginning, I made some mistakes and had trouble getting the yarn tension right which resulted in some oddities in the knitted fabric. By the end of the scarf, however, the stitches were even and consistent, resulting in a cool stretchable ribbed pattern.

Ribbed fabricFor my second project, I wanted to try something a little harder. I made the Official Kittyville hat. I used a cheap wool yarn so it wouldn’t be an expensive mess if I screwed the whole thing up. This required needles that were smaller (size 7) than the ones I used for my first project. The hat also involved some new techniques, such as knitting in the round, decreasing size, using double-ended needles, and picking up stitches in the middle of the fabric. Overall, the stitches were still slightly too tight, but the end result came out well. It’s definitely something I will wear when it gets a little colder.

Kitty hat

I’ve added lots of knitting project ideas to my ever-growing project list. I want to try combining conductive yarn and Fair Isle knitting to make functional and attractive knit circuits. Of course, there are lots of great non-technical projects in there too, like these Dalek mitts.

Knitting on a train
Knitting on a train

And, by the way, did you know that knitting is good for your health? Sources say that it is an excellent stress reliever and could possibly have the same effect as meditation.  I’ve definitely found myself getting lost in the motions of moving the needles.

Super Mario Clouds

Super Mario CloudsI took the Super Mario Clouds class this weekend at NYC Resistor. It was taught by Jonathan Dahan and David Huerta. The goal of the class was to recreate Cory Arcangel’s Super Mario Clouds project. This involved hacking a Super Mario Brothers cartridge to show just the clouds. Here is a video of his finished project:

The first step was to take apart a Super Mario Brothers cartridge. Interestingly enough, the actual board inside was much smaller than the cartridge. The game was divided into two chips: character/sprite data on the left chip and program data on the right chip. Since we were going to use the existing Super Mario sprite data, we only needed to remove the program chip. After carefully desoldering the program chip, we replaced it with a socket and a 27C256 EEPROM.

Disassembled SMBNext, We talked about how a Nintendo worked. There were some very helpful explanations in the Nerdy Nights Tutorials. The Nintendo uses a custom 6502 processor which has the audio processing built in to the chip. There is a separate picture processing unit used to display graphics. The program ROM is limited to a mere 32 KB, so Nintendo had to do some clever graphics manipulation in order to create a rather seamless side-scrolling experience.

IMG_9491The next step was to download Cory Arcangel’s Super Mario Clouds code. There was quite a bit of software setup required to run  and compile the code from scratch. As a word of warning: some of these tools work best in Windows. As I am a Mac user, I used a Windows virtual machine on VirtualBox. To run the code, we used the FCEUX Nintendo emulator. Here is a screenshot of the original code as rendered by the emulator:

clouds-3But what if we wanted to modify the code? The original Super Mario Clouds code was written in nbasic. To create a new binary, we first had to compile the code with nbasic and then convert it to 6502 assembly with nesasm. Those tools can be found here.  Finally, an NES splitter is needed to split the resulting .nes file into .chr and .prg files (for the respective character and program chips).

Once we had the .prg file, it was time to burn our programs to the chip. This was done using an EEPROM programmer. We simply selected the chip type, uploaded our binary and let the programmer software do the rest.

ProgrammerAfter uploading our programs to the cartridge, it was time for the moment of truth. We plugged our cartridges into an old Nintendo and hoped for the best. Fortunately, most of the cartridges worked on the first try!

Nintendo hackThis project was a great way to spend an afternoon with my head in the (Super Mario) clouds. Now I really want to create my own Super Mario piece. I never thought I would be so excited to write assembly code…

GPS Clock Upgrade

Ice Tube ClockToday I upgraded my Adafruit Ice Tube clock with a GPS module. The clock is beautiful but I found myself frustrated by having to continually update the time as the clock would slowly get out of sync. Fortunately, there is a handy guide on how to add a GPS module to the clock so that it can readjust the time based on GPS. It only took a few minutes to do the entire upgrade.

Clock and GPSFor the GPS module, you can use any 5 volt GPS module with 4800 baud TTL NMEA output. I chose the Parallax PMB-648 as it is relatively low cost and fits the specification perfectly. Once you have the GPS, it’s merely a question of disassembling the clock and soldering the GPS to the clock.

Solder TimeThe next step is to reprogram the clock with the new firmware. You will need a 6 pin AVR programmer for this. I used Adafruit’s USBtinyISP AVR programmer. Make sure you have AVRDUDE set up correctly. With the correct environment, it is simply an issue of pushing the new firmware that supports GPS timekeeping.

IMG_9030And that’s it. Just reassemble the clock and case and you are done. It was really cool to turn the clock back on and have it automatically adjust to the correct time. Now I don’t have to keep resetting the clock :)

Pulse Jacket

led_image_2 01This was one of my first Arduino projects. After some near misses with bicyclists while running at night, I decided to get some lights so people could see me in the dark. But why stop at boring plain lights? Wouldn’t it be cool if they could respond to my heart rate?

I looked at a number of existing heart rate sensors for Arduino, but most were optical and could not get accurate readings while I was running since they were constantly being jarred. Since I run with a Garmin GPS watch and heart rate monitor, I tried to hack into the information being sent between the heart rate monitor and the Garmin watch.

Reading a bit more about the technology, I learned that Garmin used the ANT protocol for communication between the watch and heart rate band. The good news was that SparkFun made an ANT transceiver breakout board. The bad news was that the board was discontinued and I could only get my hands on one board. I decided to move forward with this board for prototyping knowing that I would need to come up with a different solution when I made the final project.

The first step was to get the Garmin heart rate monitor and an Arduino communicating with each other. The ANT protocol documents are pretty thorough and they make great bedtime reading. Fortunately for those of us who are impatient, this thread on the SparkFun forums has sample code that already implements the protocol for the Garmin heart rate monitor.

Microcontroller with ANT breakout boardNow that I had the pulse rate information, it was time to add lights. I am a huge fan of Adafruit’s LED strips. These strips have weatherproofing so it would be possible to run outside in the rain. I trimmed the strips to the length of my arms and sealed the ends.

Microcontroller with lightsI added seven different light modes which increased in speed with the heart rate: rainbow, raindrop, range pulse, color shot, twinkle, circulatory and Cylon. Most of these modes are self-explanatory. The range pulse mode faded the strips in time with the pulse and also chose the color based on the current pulse rate (blue being low pulse, red being high). Here you can see a quick demo of the seven modes:

I then began building the final version. For this, I chose to use a Teensy 2.0 because of its low price and small size. I also had to revisit the ANT transceiver. Searching around, I found this ANTAP281M5IB  module with an on-board antenna. After some very delicate wiring and soldering, this proved to be a direct replacement for the SparkFun board.

IMG_8863 Once everything was working, it was time to put this into a portable package for running. The main concern was power. After a bit of research, I found these Energizer power packs that I could plug directly into the Teensy. The one amp power pack would power both LED strips for about an hour. After verifying that everything still worked, I placed the assembled project into a small project box.

IMG_8862The last issue was how to attach the LED strips to my arms. I thought about embedding them into a jacket by sewing them in, but I decided against that as it would be a pain to clean. Finally, I just glued some cable clips to the back of the LED strips and used velcro straps to adjust them for the right fit.

Assembling the arm supportsAssembled JacketAnd after all that we were ready to go! My first real-world test was the Midnight Run in Central Park on New Years Eve 2013.

New Years Eve - 2013New Years Eve - 2013And now I can easily be seen in the dark!

Miscellany by Miria Grunick