Sunday, April 21, 2019

Kindle Art Projection

This project uses a camera to project an image across multiple Kindle displays. You can move each Kindle to show different parts of a larger image.

Any image can be used, but this particular setup displays sections of  "A Sunday Afternoon on the Island of La Grande Jatte"- the painting's texture shows very well on the e-ink display.

Every few seconds, a controller (consisting of a raspberry pi zero and a camera) instructs a Kindle to black out the display, then illuminate each of its four corners. The controller records these five images and subtracts the black base image from the corner image to get a difference:

Result of "corner - base" image

Output to the Kindle

Points on the screen recognized by the controller and camera

I recently found out that the going price for a working used Kindle Touch is about $20, and that they are remarkably easy to jailbreak. Using a controller with SSH permissions, you can update the Kindle display to show any image through the eips command.

The controller resides in this 3D printed case

Here is a video of the art display in motion:

Code is on GitHub:
I was inspired by a few artistic Kindle hacks:

"This homemade literary quote clock is the best way to recycle an old Kindle"
"Animated Picture Frame Needs Charging Once Per Month"

Wednesday, March 6, 2019

Smart Coffee Maker

I wanted to be able to control my coffee machine using voice, and more importantly, be able to start the brew process as soon as I wake up. Of course, I still have to grind the beans and load up my coffee machine, so it's not fully automatic.

This is just a simple relay, powered by a Raspberry Pi and a custom Alexa Smart Home skill.

The SmartHome skill invokes an AWS Lambda hosted on my AWS account to control the device. That lambda drops a message in an SQS queue, and my Pi watches the queue for updates. When it sees an update, it toggles the GPIO pin connected to the relay, toggling power to the coffee maker.

One interesting hack is that the Smart Home skill requires integration with some OAuth provider. If you're developing your own skill for your own home, you can just use Login with Amazon as the OAuth provider and disregard the identity in your skill. This guide explains how to enable Login with Amazon for your skill: 

Sunday, January 6, 2019

IoT button notifies you when laundry is done

The AWS IoT button is a few years old now. This is one of many gadgets I bought before knowing its use. Today it's glued to my washer/dryer and notifies me when my laundry has finished. Just tap once for the washer or twice for the dryer.

The code is very simple. A Lambda function is invoked, which starts a StepFunctions workflow execution. The workflow waits a specified duration of time (37 minutes for my washer, 107 minutes for my dryer) before sending an SNS message. My cell phone is subscribed to the SNS topic.

Code is on GitHub here:

KSMO and back to KBFI

I successfully made the trip all the way down to Santa Monica (KSMO) and back to Seattle. Rather than journaling in two places, I ended up keeping track of the trip on my Instagram:

Posts are embedded here

A post shared by Dylan Rush (@dylanhrush) on

Wednesday, December 12, 2018

KBFI -> KVUO - Portland OR

I took off from Boeing Field this afternoon in an elderly Cessna 150M, N7991U. My plan is to travel up and down the West coast. San Diego would be a stretch goal. Los Angeles would awesome as well.

Today I planned on stopping in Hillsboro and continuing to Eugene, but weather was uncooperative.

Headwinds were quite strong; I often measured just 59 knots across the ground. I had to temporarily divert to Kelso to refuel when HIO showed IFR conditions. I made it to VUO (Pearson Field, Vancouver WA, just north of Portland) to stay for the night.

Wednesday, July 11, 2018

Nixie Tube Clock

My brother bought me some nixie tubes for my birthday a while back. They sat in my desk drawer for a long time, until I finally got around to building this clock.

The nixie tubes are driven by four SN74141 IC's and a 180v power supply, hanging off the back:

I control it with an Arduino and a DS1307 RTC module, keeping battery backup. The button on the side can adjust minutes or hours with short or long presses.

This was the first time using 3D printing in a custom electronics project. I sketched the model using Blender. The PCB's slide into their respective sleds, and a front gate locks the main PCB in place. The enclosure is designed to be replaceable.

Soldering this beast took a few weeks. I'm going to try printing my own PCB next time.

I resurrected my old Printrbot Simple from five years ago. With a ton of tweaking and calibration, I was able to print the rear sled and bracket, but it was unable to finish the full 10cm base.
So, I finished the base and front gate using an Ultimaker from work. What a beaut

Code and enclosure model:
Help from:

Saturday, July 15, 2017

Live Sectional Map

A polished and well-crafted variant of this project was featured on HomebuiltHELP's Tip of the Week

The Live Sectional Map is a small cylinder showing the aeronautical sectional chart around Sea-Tac. Seven airports are illuminated with colored LEDs. When the cylinder is plugged in, it will download the METARs for these airports every minute, and update the color for each airport depending on the conditions.

Just like ForeFlight, VFR is green, MVFR is blue, and IFR is red. LIFR flashes red.

The map was super glued around an old Quaker oats can. I wrapped it in rubber bands for a day to let the glue settle.

I drilled holes for each airport and hot-glued common cathode RGB LEDs to each airport.

After experimenting with an Arduino like I did with Thinking Man, I decided Arduinos are a pain to connect to WiFi, and Raspberry Pis are much more robust. I SSH'ed onto a RPi running Raspbian on headless mode while developing. The RPi's GPIO ports control each LED anode.

I used a simple GPIO breakout along with female-female jumpers to connect each LED. The cathodes were strung along this awkward extension, shown below. I used a 200 ohm resistor on ground for the whole circuit. Later I found out the red LEDs ate a lot more power, and would dim rival blue LEDs when in use. Rather than put 21 resistors on all of these anodes, I just balanced the color using pulsewidth modulation through the RPi.GPIO library. Code: