Fig. 2.

RespiCo. A. RespiCo breadboard – showing interconnections between the HUZZAH32–ESP32 Feather Board and the discrete electrical components. The figure was made using Fritzing (v 0.9.4), an open-source hardware initiative, and annotated. Red and black represent power leads; yellow represents signal leads; the JST PH connector for a lithium ion polymer battery power connection (a), and a mini USB connector provides power and a serial connection (b), if desired. B. RespiCo prototype: Left –the top board containing the discrete electronic components and connectors (c), HUZZAH32–ESP32 Feather Board (d), and connected battery (e); Right - the assembled RespiCo prototype. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)