Sound Synthesis with Arduino // eTextile Spring Break

This is part of a series about last week’s eTextile Spring Break, held in Wassaic, NY. I sponged up a ton of knowledge about integrating electronics and textiles, including thermochromic pigments, soft interfaces, radio technology, and more! Here are my notes from the first workshop I attended.

We had a three-hour workshop on each of the first few mornings (with 2–3 options each time). I chose one on audio tech, taught by Adrian Freed and Martin De Bie. We worked with SparkFun’s Lilypad and Adafruit’s Gemma M0.

We got acquainted with a few Arduino libraries that Adrian has modified:

• FastTouch provides excellent touch feedback with examples for the Lilypad and Adafruit’s Circuit Playground Express. (See 1:00 in the video above!)

• Mozzi allows your Arduino “to produce much more complex and interesting growls, sweeps and chorusing atmospherics”. There are plenty of ways to shape the sound that you want, similar to an analog or virtual synthesizer. I’m really looking forward to playing with this one!

• Talkie is a speech library for Arduino. We had a little trouble getting this one to compile for the Lilypad, since apparently there is an issue with an update that includes the SayQ command; as a result, you must modify the sketch to use SayQ instead of the say command. I also ran into an issue with the qBlink command, so I removed that and all references to it in the example. (See the video below!)

My favorite thing about the Talkie library is that it includes a sketch which plays a lo-fi version of “Tom’s Diner” by Suzanne Vega! (That one had to be loaded on the Gemma M0, since it takes a bunch of memory.) You can hear it at 5:30 in the video above. :)

On to the physical part… Martin and Adrian had worked up a fabric patch breakout for a 555 timer chip. (The 555 is popular for music, radio, and MANY other applications; here’s my demo with it.) It’s a work in progress, so I won’t share the exact details, but the method of construction is really cool:

• An iron-on backing is applied to copper taffeta fabric.

• A Silhouette Cameo cutter (or other vinyl cutter) is used to cut the fabric into solderable pads.

• By applying masking tape to the top of the cut surface, you can pick up the individual pads in their proper orientation, and apply this to neoprene fabric (about 2mm thick).

• Using a full-size or craft iron, place another piece of thin fabric on top, and carefully heat the assembly, so that the iron-on backing melts the two layers of fabric together.

This gives you a soft circuit board! It’s a bit more versatile than building flex PCBs with copper and kapton tape, but also thicker and perhaps less precise.

You have to be careful when soldering parts on, because it’s easy to burn a hole in the copper fabric (or the neoprene, I suppose).

I also found out about the Hornbill ESP32 Minima, a Lilypad-format board with WiFi capability! Very sad that this is no longer in production.

Plus, there was this CraftMates binder with little plastic component tubs held in place by a plastic sheath. It closes with two snaps, and seems incredibly handy for all your small bits of tech candy. Have to say I’m jealous!