The Technomancer Robe from ThinkGeek has been my Halloween costume every year for the past nine, and every year I wonder how it could be updated - what if I could create my own spells, my own custom lights, my own sounds? Behold, Technomancer 2.0! Use hand gestures to cast spells, driving light effects across your arms and face with sound in a system built to be worn with anything. The brain box rests inside a camera bag or backpack with the lights mounted on bracers, a headband, and a bottle.
The parts are sourced from Adafruit and Amazon. INSIDE: Propmaster RP2040 as the brain; LTC4311 to extend the Stemma QT signal; UDA1334A to add a secondary stereo out port, connected via stereo cable passthrough; a USB-C breakout board for one power bank to power the DotStar LED strips and 8x8 matrix; a USB-C passthrough cable to power the Propmaker which powers the UDA1334A and two potentiometers (brightness and volume); one 4-port splicing connector for incoming 5v power distribution; a second 4-port splicer to split the PM's 3.3V to the pots; an 8-port splicer to connect all the ground wires back to the USB-C breakout; two GX12 and two GX16 connectors to route all the wires through the box by destination. OUTSIDE: The main destination is the right bracer, which has mounted to it a DotStar strip for under-glow (inside sleeve); passive 4Ω 3W speaker for localized sound effects; Stemma QT chain containing APDS9999 for color and proximity sensing, and an LSM6DSOX for accelerometer readings. The sensitive Stemma signal wires and speaker wires are protected from EMI by sleeving them in a tinned copper loom, which is then bundled with the LED lines inside a black cable sleeve. The left bracer has the same DotStar strip. The neck has another DotStar strip. Finally the potion bottle contains an 8x8 rigid DotStar matrix. The stereo jack can be used to connect directly to a self-powered speaker, or to a Bluetooth speaker using a BT transmitter.
There were several difficulties to get this to work, especially since this was all new to me. The biggest challenge was understanding space: my initial plans were to have the project box be small enough to fit on an arm-band phone holder or a slim hydration backpack, and ended up barely fitting in a 5”x5”x3” Junction Box. Along the same lines, learning to solder by connecting 22 wires onto both sides of the GX aviation connectors was, at times, maddening - especially when I forgot to add a heat shrink, or when I tried (twice) to fit 6 wires onto a 6-pin connector and ruined them before switching to an 8-pin for the extra room. I also had to wrestle with my own ambitions and time limits, and my plan for this project isn’t complete. While adding each piece I was able to get the code to work. For example, the PM’s accelerometer could drive a fluid sloshing of the potion bottle, which would drain as “cast” was typed into the serial monitor and slowly refill over time. Or I have code which will play a WAV file through the speakers when a cast is made. However putting it all together across the PM’s two cores will take more time, so what the code drives now are steady lights and a swirling potion bottle, with the brightness controlled by the first pot. What I will be adding are two more strips of high density (144 LED/m) to the back of the right bracer to show resource management (Health and Mana bars). On the right hand will be mounted additional LEDs for spell effects; the APDS will allow me to sense short distances, so hands together will make a small fireball glow which gets bigger as the hands separate, and I can place my hand on something to make that color wash over me. I will use the machine learning of the LSM6 to place the gesture spell logic there and have it send just the command to the Propmaker. I would also like to add an MPR121 capacitive touch sensor, wired to the metal rivets on the back of the bracers - giving it secret buttons for spell control. All told I started this project last month and I feel very accomplished - I can’t wait to keep going!