The Mindfulnest project is developing a program to promote mindfulness practices in preschool classrooms. Simple controller devices are used by the kids. These have lights to give feedback to the user and a sensor that targets a desired behavior such as steady breathing. The controllers attach using bluetooth to a tablet which implements the interaction algorithm and logs data for research.

The controllers were initially developed by others as handbuilt prototypes made from stock development and breakout boards. I was brought in to redesign the controllers to be produced in higher volume by making custom PCBs integrating all of the parts. I assembled 10 units myself, and then for a new 50 unit build I got the board assembly outsourced.

This involved rewriting the firmware to port it from Arduino to run on the Zephyr realtime operating system. Zephyr is a portable and fairly featureful operating system targeted by several major microcontroller and sensor vendors. While we didn't need much beyond the Bluetooth protocol stack it was still necessary to figure out how to configure Zephyr for our custom boards. This took considerable time and effort to implement and troubleshoot.

The overall esthetic design of the controllers was already established, but I did a great deal of work on the existing Solidworks models, getting them to build again, refactoring the models to have a cleaner dependency flow, redesigning joints to be stronger, reconsidering fastener choice, and adding features to promote correct alignment during assembly so that the switches would operate smoothly and the buttons wouldn't fall off. These parts are printed in SLS nylon for structural parts and resin for the translucent features and the button.