The Micro One-Armed Bandit

Over the holidays I came up with an idea to create a micro slot machine coded in #CircuitPython using the Adafruit 5×5 NeoBFF Led Matrix. A micro switch, or limit switch is used to ‘pull’ the slot machine arm. A Piezo buzzer bleeps and bloops familiar tones and may signal a win. Ding-ding-ding!

I paired this add-on board with the Atmel SAMD21 QTPY microcontroller which provided some issues with limited memory. This particular microcontroller has constraints which made this a fun challenge. The ESP32 and RP2040 versions of QTPY microcontroller boards on the other hand would allow for more advanced libraries to be used out-of-the-box and thus could have a much different solution.

If you’d like to jump straight to the CircuitPython code you can find it here:
https://github.com/somenice/micro-one-armed-bandit
Otherwise I’ll walk through the build and code.

Parts required:
Adafruit 5×5 NeoPixel Grid BFF Add-On for QT Py and Xiao
Adafruit QT Py – SAMD21 Dev Board with STEMMA QT
Piezo Buzzer
Micro Switch w/Lever
Header pins and a bit of wire
Optional: Right angle USB-C cable

Pins used:
The micro switch – ‘NO’ or Normally Open pin is on A1
The Piezo is on pin A2 which requires PWM
The 5×5 matrix uses pin A3 by default
All share ground

I first clipped 2 header pins of 7 then soldered the 5×5 NeoBFF on top of the headers while fitted in a breadboard. Next I soldered the QT Py board to the bottom of the headers, back-to-back, making sure to line the boards in the correct direction which is smartly printed on the back of matrix.

There is really no case or supports. The lever arm and piezo buzzer were soldered to the back with bits of wire dead bug style.

Back, top, bottom, and side views of wiring.
A piece of heat shrink tubing is wedged for some protection against short circuits

The right angle USB-C cable is perfect to have the matrix sit upright.

Almost all code is derived from some Adafruit CircuitPython tutorial.
One of the key functions of the micro switch as slot machine arm was to have the action happen on the release or rise of the lever.
This was made easy with Adafruit Debounce library.

from adafruit_debouncer import Debouncer
if switch.rose:

The idea of the slot machine was to have 5 “Reels” which get randomly offset as they “spin”. Most physical slot machines will have different reel sequences but this example uses just one.

I declare hex values to identify the colour then manually created the “Reel” with different colour frequencies. Note the number of RED instances vs PURPLE.

RED = 0x100000
REEL = [RED,GREEN,YELLOW,BLUE,PURPLE,YELLOW,RED,GREEN,BLUE,RED,YELLOW,RED,RED]

On release of the lever the first step is animate the existing columns down until coming slowly to rest with a random offset on the reel.

Yup, this whole thing relies on random.randint(0,len(REEL)) So not a hardened gambling system.

I played with piezo tones, simulated physical mechanisms and settled on some familiar notes that some 8-bit fans may remember while collecting coins in another world. The final slot gets a slightly higher note, adding that audio and visual stimulation.

One of the most fun and satisfying puzzles was working with only the Adafruit CircuitPython Neopixel library to animate the 5×5 RGB matrix using a nested loop of columns and rows.

for i in range(5): #COLUMNS
    for j in range(5): #ROWS

Using various math equations, very simple but new-to-me discoveries via trial and error to produce very satisfying results.

pixels[20-(5*i-j)] = #TOP LEFT ACROSS
pixels[20-(5*j-i)] = #TOP LEFT DOWN
pixels[5*i+j] = #BOTTOM LEFT ACROSS
pixels[5*j+i] = #BOTTOM LEFT UP
pixels[24-(5*i+j)] = #TOP RIGHT ACROSS
pixels[24-(5*j+i)] = #TOP RIGHT DOWN

Once again, you can see the code and fork here: https://github.com/somenice/micro-one-armed-bandit

As earlier mentioned, the memory constraints were a fun challenge as well as using minimal parts on a basic microcontroller.
Being a hobbyist with almost endless access to sensors, radios, and actuators can often lead to scope creep. Nothing stopping me from endlessly adding functionality until I get bored and quit. This one was fun to get at least to V 0.1

Wooden Macropad

What is it?

It’s an open source electronics kit, the Adafruit Macropad, embedded in a solid block of quarter-sawn tigerwood.

What can it do?

It’s a programable HID keyboard with OLED display and rotary encoder running CircuitPython. Which is a hardware specific, light-weight port of Python for microcontrollers.
The keys have RGB LEDs and can be programmed to send single or multiple keystrokes to the computer.

It shows up as a mountable drive, you can live-edit the code.py file so
when you save, the new code is automatically loaded. No compiling.

Similar to other computer mice, keyboards, or other peripherals it’s powered by USB so it does not run standalone.

The Woodworking began as a solid block of South American Tigerwood. Nice pattern and hardness but I can’t say I enjoy the smell of this wood. It’s got a gluey stank which is not particularly enjoyable.

I used a bandsaw to take a 1/4 inch veneer off the top. This will be the cover.

The bottom base was hollowed out using a plunge router. A device you must respect. It can clear out a lot of material quickly but at 10k to 30k RPMs it can easily get away from you in a hurry. Safety always first.

The two two pieces were then carved and fitted to accept the Macropad. It’s a bit of a shame to seal up the beautiful silkscreen art of this particular PCB.

The fitted Macropad had one other addition. I used a cut down credit card sized plastic magnifying glass using lenticular? magnification. The offset from the OLED gives the display a slight floating feeling.

Macrophotograpy of the Macropad

The project was finished with a couple coats of MInwax Tung Oil finish. Not a “true” tung oil but it makes the grain pop while not filling the wood pores.

The seams are a little more visible than I would like. From a distance however it’s not that noticeable. I’ve learned that minimal handling is required after separating using the “bandsaw box” technique to prevent “dings”.

As for programming I’m mainly using the application hotkeys demo found on the Adafruit Learning Guide but the sky is the limit because it can be programmed to do anything a keyboard or mouse can do.

Motivation to write this up comes from the recent Hackaday.io contest for Odd inputs and peculiar peripherals.

Radioactive film lenses and Geiger counter Kit

The Super-Takumar 50mm f1:1.4 and Mighty Ohm Geiger kit
The yellowing of the lens caused by the radioactive decay.

Last week marked the ten year anniversary of the Japanese earthquake and resulting tsunami that caused the Fukushima Daiichi nuclear disaster.

In the years following that tragic event, flotsam began arriving on the Pacific West Coast. Volunteers making great effort to return personal items back to family and loved ones in Japan.

Models showed the ocean currents and their possible nuclear contamination as it crossed the Pacific Ocean.

My interest in sensors and environmental monitoring led me to the relatively inexpensive Mighty Ohm Geiger Counter kit. A fun open-source microcontroller-based Geiger counter kit you solder together yourself.

Years ago I began collecting vintage film cameras, still occasionally shooting and developing my own B&W film today. Ebay was a great source for these antique objects of optical and mechanical precision, which were practically given away in the early days of the digital camera’s rise. Some film cameras are still sought after for collectibility and some manual focus film lenses got a new life with the use of adapters on digital cameras.

While I had an interest in detecting any increased environmental radioactivity from the event as a citizen scientist, my main motivation was testing old film camera equipment.

One of my favourite Ebay film camera purchases that I still use today is the Asahi Pentax Spotmatic SP. I got it as a “kit” with a large assortment accessories and quality lenses. At nearly 60 years old, these Super-Takumar screw thread M42 mount lenses have such a precise feeling. The range of prime lenses in this purchase included:
Wide angle 28mm f3.5, Zoom 135mm f2, and Fast 50mm f1.4.

Small yet surprisingly hefty, the only way I can describe the focus dial is like the volume knob on an expensive stereo. Smooth resistance. The aperture dial clicks into each stop without wiggle. Lens covers are friction-fit without mechanical fasteners, hoods and cases, straps all immaculate condition and with such tight tolerances. I need a thesaurus for additional words for “precise”.

From this camera, and the 50mm f1:1.4 specifically, I created one of my personal favourite pictures of all time.

I have however heard stories of some lenses being radioactive and also that some cameras may have been looted from nuclear contaminated sites such as Chernobyl.
In the late ’90s my camera of choice was a lomo smena 8m. Used mainly backpacking, there is really no lighter fully manual 35mm camera.

There are plenty of forums, articles, and Youtube vids, listing/discussing radioactive lenses. Thoriated glass was used for it’s optical properties perhaps before the effects of prolonged exposure to radiation were fully understood. While many dismiss the risks associated with owning or using this radioactive equipment, I’ll leave it for the reader to make their own informed decisions.
A comical radiation dose chart from XKCD.com

I’ll admit, until I had a source of beta or gamma radiation, my geiger counter was essentially a really great random number generator. Blip… blip….blip. blip

My radiation detector is capable of detecting beta and gamma radiation but alpha radiation can not detected. A bit more reading about Thorium232 tells me that it actually decays emitting alpha radiation though.

Hang on, what’s going on?

Turns out the decay chain releases a “cascade” of fun alpha, beta, and gamma particles. The latter saturating the Geiger-Mueller tube sensor.

From the serial monitor getting close had the following readings:
CPS, 18, CPM, 1080, uSv/hr, 6.15, FAST

Though detectable only close to the source, it’s hard to read these kind of numbers and say I want to go out and hold this up to my face for half a day.

And keep it the house with my family for years to come? Nope. Topes lose, Topes lose.

I wouldn’t even consider selling this lens at this point, even to someone who fully acknowledges the risks. Because while they might accept it, the logistics people, delivery drivers, shippers or anyone in between didn’t agree to that.

Question is, where and how do you dispose of this hazardous, gorgeous, and “precise” material?

UPDATE: I’m now in touch with the Historic Artefact Recovery Program (HARP)
Operated by Canadian Nuclear Laboratories (CNL). The HARP
provides technical advice, assistance, identification and management of radioactive artefacts found on public and private
properties across Canada. Where necessary, the artefacts are transported to a licensed long-term storage facility located at
CNL’s Chalk River Laboratories in Chalk River, Ontario.

“Big Flood” lightbox

Blue led animation in steel laser cut Coast Salish artwork

Using the Adafruit Adabox #017 I added leds and an e-ink display to a lasercut lightbox made of steel by Coast Salish artist Xwalacktun as a gift this year.

A miniature version of He-yay meymuy (Big Flood), it’s 30cm tall with an 11cm diameter. The original piece is an impressive 487.8cm tall by 167.6cm made of aluminum. Located at the entrance to the Audain Art Museum, it’s is a powerful piece inside a beautiful building.

I used a metre of RGB neopixels wrapped around a cardboard tube, diffused with the bubblewrap, and plugged into the Adafruit Magtag to animate rain. In this mode the lightbox will eventually fill to a full blue colour.

There are three other modes with different colours and animations using the Adafruit_led_animation library. Each mode animates differently and updates the e-ink display with a section of art from the lightbox.

Adafruit MagTag eink display
Top View: With e-ink the last image will remain, even after removing power.

I even upcycled the spool from the neopixel strip to mount the MagTag as it fit snuggly. There are plenty of other features I’ve yet to take advantage using built in Wi-fi, light sensor, etc.

Art by Coast Salish artist Xwalacktun
296 x 128 px Indexed Colour .BMP used to display on e-ink

The base is made with glued pieces of western red cedar to mimic the architecture of the museum and carved to receive the artwork.

Grow Conference 2014

grow
I just attended the Grow Conference here in Whistler and I wanted to share a couple thoughts.

Billed as “an experiential playground exploring the future of innovation, growth and entrepreneurship” the conference tagline is LIVING IN A CONNECTED WORLD. These themes are near-and-dear to me so I was thrilled when they announced they were coming to Whistler this year. Offering a Lean pass, I was able to secure a fair priced ticket without the need to pay for transportation etc.

The conference, which took place at the Fairmont Chateau Whistler, was well organized and aside from a couple audio and scheduling issues, everything ran smooth. Along side the conference was a two day hack-a-thon. The challenge; To create a “connected” resort town! I wish it preceded the conference so that I could participate in both.

The mix between technical and non-technical attendees kept the discussions mostly high-level. The people I tended to connect with were lower-level developer types. With my poor entrepreneurship skills, I was unable to secure millions of dollars in venture capital. I wasn’t actually trying to sell anything. Except maybe Whistler. I would offer local advice, help every lost attendee, and generally just say “how awesome is this place eh?”. I probably wouldn’t have turn down 100k for my idea to start a hackerspace here in Whistler. In fact, I am trying to start a hackerspace right here in Whistler. Sadly, this town isn’t filled with geeks. Only few local tech companies like Guestfolio and Ridebooker here in Whistler and they represent a small percentage of the employers. No reason this can’t increase.

A few highlights and common themes;

Wearables and Internet of Things – These are definitely the hot topics getting all the attention. The Internet of Things (IoT), which everyone mutually agrees is a poor term, seems what you call any connected device that’s not a computer. Wearables, obviously are worn. Think Google Glass, Recon Instruments, fitbit, Nike+, etc.

Privacy and Security – These topics always come up immediately afterwards. As soon as you think “Cool, I can open my door from the internet” you realize that theoretically anyone else can too. That sleep monitor, check-in data, and all the things tracking you for convenience can be mined or interpreted and used against you. My opinion is those that take this serious will win out.
I was very impressed with SmartThings founder Jeff Hagins opinion on the subject and glad they are staying separate from Samsung after just recently being acquired. I can’t say the same for lax attitude of Life360, whose founder repeatedly made broad statements like “I don’t think your average user cares”. Their product GPS tracks family members btw.

Data – Data, Data, everywhere data. It’s not enough to just collect it, you need to use it. Inform.
Scale, infrastructure, APIs and the other things that were once hard have since been figured out. Some companies whole business is collecting customer data. Once you have the data… (see Privacy and Security)

Best talk and what resonated with me most was Scott Jenson’s How to make everything discoverable with the Physical Web.
In it, he smartly discussed how the physical web will need a mechanism unlike the current app model. The idea that every future smart-thing would require it’s own smart-app obviously has flaws.
Just Google “app fatigue” and you’ll see for the past year or so the world isn’t very appy anymore. Yay web! And that’s the idea, broadcast URI’s, no passive tracking. I’m looking forward to experimenting with this. You can too. Find out more with examples on GitHub.

Overall it was a great conference. I hope to be back again next year.