Busy hands | Disquiet mind

Every so often I take a fancy to the idea of taking up the piano again. I was going through one of these spells when I came across this project, the Piano LED Visualizer. How could I not give it a go?

I ordered the suggested Waveshare LCD TFT 1.44" 128x128px, WS2812B LED Strip (144 per metre), 5V 6A power supply, silica tube strip in T0515 for 12mm in 2m length, and iConnectivity mio midi-to-usb cable. (I had a cable already, but thought it wasn't working. Turns out the port labels on my piano are backwards. (If I keep writing it everywhere maybe I'll actually remember next time.)) I already had the Raspberry Pi Zero, and miscellaneous components. As well as a digital piano. Time to get soldering.

I know the instructions say there's no need to solder, but I did anyway. I used a Pico hat hacker board and soldered the connections on to it. The idea is to wire up the power between the LEDs and Pi as in this article. Checking the pinout that looks like Data out on pin 12, and I used pin 34 for common ground. Then soldered a few connectors/adapters, before seating the Waveshare on top, installing the software, etc.

At this point it all works, but it's a loose bundle of components, so let's make that case. The instructions really gloss over this part. The case is this model, but it's based off this original case for PinkyPi. Which is where I found the guide that finally told me I needed M2.5 screws, standoffs, and nuts to assemble everything together. (The direction pad button is wonderful, but the other ones did not work for me at all. At least I can still reach the buttons through the opening in the case.)

I also ordered the midi usb-to-usb adapter needed to try the Synthesia feature, but haven't had a chance to try it out (due to a major mix up in shipping, that the seller was great at getting sorted out, but it took a while).

Overall the LEDs lighting up next to the key you pressed is neat. And you can set the LEDs to play animations if you just want background lighting, say for a video chat. But the LEDs don't line up well. I don't know if it's just because I got a cheap set of LEDs, but they are off at each edge of the keyboard by a couple of keys. Overall this feels like an early version project, but all the important parts are there. Including the software which is fairly solid. And it's very fun to play with.

( Photos )

Piano LED Visualizer in rainbow demo pattern
Photo by chebe

As I do more with electronics I get more complicated ideas, which necessitate learning more. At the moment I want to run 5V NeoPixels from a 3.3V microcontroller (i.e. Arduino Lilypad) which doesn't have a handy MOSFET pin (like the Adafruit Flora). I studied the NeoPixel best practices guide repeatedly. The new requirements boiled down to;

- 300 to 500 Ohm resistor on the Data In line of NeoPixel strip (which will be added to the NeoPixel end),
- capacitor (1000 µF, 6.3V or higher) across the battery terminals,
- logic shifter to up the 3.3V Data Out from the microcontroller to the 5V Data In for the NeoPixels.

Okay, great. Now where am I going to get the 5Vs from? 4AA rechargeable batteries would give me 4 x 1.2V = 4.8Vs, great. But, what if I accidentally grab alkaline batteries by mistake? That would result in 4 x 1.5V = 6Vs. Which is enough to damage the NeoPixels. To protect against thoughtlessness I would need a 5V voltage regulator. But, hang on, why don't I also add a 3.3V voltage regulator and remove the need to power the microcontroller with a separate power source? Just have to make sure everything has a common Ground.

Great, okay, so that's two voltage regulators. And the recommended bypass capacitors; 1µF on input and 0.1µF on output. This is a lot. Let's sketch it out. A few times by hand, then in Fritzing.

( Process )

Then it's time to commit it to solder. It all fits on a half-size breadboard, and you can use any, but the ElectroCookie board has a continuous ground line if you bridge the break, which saves me work. Also, bonus cuteness.

Finished circuit soldered
Photo by chebe

( Testing )

Following on from the RGBW upgrade the lightbox just needed some finishing touches. I finally got my Feather 32u4 Bluefruit LE (Adafruit / Pimoroni) working. Hint; you need the example code at the very bottom of this tutorial page, it has all the bits and pieces actually hooked up. The other code just prints hex code to serial, doesn't actually set any NeoPixels.

I first tweaked this code to work with RGBW strips instead of RGB;
//Adafruit_NeoPixel pixel = Adafruit_NeoPixel(NUMPIXELS, PIN);
Adafruit_NeoPixel pixel = Adafruit_NeoPixel(NUMPIXELS, PIN, NEO_GRBW + NEO_KHZ800);

//pixel.Color(255, 255, 255)
pixel.Color(0, 0, 0, 255)

Then I set about changing the behaviour. This is first and foremost a lamp, so I set the default behaviour upon power-on to be white with medium brightness. Then I played around with what the buttons in the app would do. I can increase/decrease brightness, reset to default, pick a colour, and play a couple of animations, all in software. Which seems to meet my needs nicely.

Finally I soldered some headers onto the Feather pins for modularity.

The next issue was making the power convenient. Which in this case means mostly mains powered, but not permanently removing the battery option. Also sturdy, and not the slightest bit fiddly. I went with a barrel jack to JST cable (SparkFun / ProtoPic) for inside the lightbox, and barrel jack to USB cable (SparkFun / ProtoPic) for outside the lightbox. I also added a USB cable with switch (Adafruit / Pimoroni) to the mix for even more usability.

The barrel jack to JST cable needed a hole drilled in the case. Flush so it wouldn't leak light, or get in the way when using batteries instead. I used a rotary tool to drill out a nice little circle.

( Details )

Then it's just a case of closing everything up again, plugging the whole thing in to mains, and enjoying.

Lightbox with new mains-via-USB power cable
Photo by chebe

A long time ago I acquired a hat. Some time after that, still a long time ago, I added a blue LED strip to the band. Later again I replaced the silver ribbon with a black ribbon, removed the original hat band (cutting the glue off the hat), hot-glued a felt pocket to the inside to hold the battery, and cut a slit so the wires could pass through.

But single colour LEDs? Running off a 9 volt battery? Not good enough nowadays. Enamoured with potentiometers of late, I got the idea of doing a red-green-blue plus brightness mixing board. (Bonus points for not using radio, meaning it would remain functional at maker/hacker meetups where radio frequencies are often saturated.) I found myself in Makevember so I did up a quick breadboard prototype.

( images )

But once I had that done I wanted to add extra modes, controllable by pressing the push button a number of times. The first one I added was Rainbow Cycle (I'm using the Adafruit Neopixel library rather than FastLED here).

Rainbow pattern
Photo by chebe

( Videos )


Parts;
Hat
Adafruit Mini Skinny NeoPixel Digital RGB LED Strip, 60 LED/m
Adafruit Flora
Bakelite Perfboard
Potentiometers
10K ohm resistor
Momentary push button
Headers
Various jump leads
LiPo battery

I've had an idea for an elaborate electronic skirt for, literally, years now. And no matter how long I waited progress just wasn't being made. At one point I realised that EMFcamp was fast approaching and I needed something for it. So I scaled back my ambitions, found a white tulle/net skirt on sale, and got to work.

I had a few Neopixel strands laying about the house, and found to my surprise that each 20 pixel (2" pitch) strand was almost exactly the width of my skirt. Two strands would completely encircle it. Rather convenient. And I wanted to be able to set the colour of the Neopixels from things around me, so I needed a colour sensor. I also wanted a potentiometer so I could adjust the brightness depending on ambient light, and would need a button to change between modes. Oh, and a microcontroller to make it all work. Which gave me this circuit.

( Details )

But white is very much not my aesthetic. Which is a large part of why I made this an underskirt. You can use this one underskirt with a variety of overskirts to achieve different effects. Here I've used a black crushed velvet skirt with uneven hem so that some of the glowing tulle/net still peeks out. In dark enough environments, there is a side benefit of seeming to exist in a puddle of light on the ground. (Which can be handy when trying to navigate a campsite.) Overall this skirt is fun, but not the most practical. Though I do foresee it coming in handy from time to time.

Skirt
Photo by chebe

Parts;
Fabric scraps
Petticoat
Skirt

Potentiometer
Adafruit Flora
Adafruit Neopixel strands
3-pin JST SM Plug + Receptacle Cable Set
Adafruit Colour Sensor
LilyPad Button Board