(July/August 2015)

Erica wants to learn processing, so she asked me to create a programmable widget that she can talk to and control. She wanted a light display with the ability to interact with it via touch/proximity sensing.

To get her started, I hooked a NeoPixel strip from adafruit to a Arduino Micro, and developed a serial interface to it in processing that she could use. In the meantime, I started looking into options for what to build. First was a process of looking at all the plausible display and sensing options:

We settled on raw WS2812B with the IR transmitters and receivers on each side. The first prototype with sensors had a 10mm cell pitch, and was made on some SMD protoboard with parts on hand. The Color LEDs were the original WS2811 (6 pin) variety, and the IR LEDs and phototransistors were leftover from a project at work.

I realized the IR LED and phototransistors would interfere with each other in this configuration, so I alternated them when I expanded the prototype.

This density was a bit much, but seemed possible. I was able to hook this up to an Arduino and show that the basic concept worked. We then worked out a cost matrix for different options and densities, to estimate total project cost (of the major components) based on this basic design, selecting Option 5 in the end.

The next post will go through the PCB design and BOM.