This case study has not been published yet. The live site shows only the introduction, you're reading the full draft here. Content may still change before release. If you'd like to suggest changes, contact me.

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MTronic building automation

Motion and Light Sensor

The MTronic motion and light sensor is a ceiling-mounted, battery-powered device for the MTronic smart home automation platform. It detects room occupancy through a 360-degree passive infrared field and measures ambient light continuously, and it is the input the rest of the system depends on to automate lighting and climate. If the sensor is unreliable or frequently out of battery, the automations that sell the whole ecosystem stop feeling automatic.

MTronic motion and light sensor ceiling-mounted unit

I was the sole firmware engineer on this sensor across two hardware generations. I joined when the first ESP32-C3 prototypes (V1) had been fabricated, and through systematic power profiling I found that the platform could not be pushed past a roughly 9-month battery life. That was below the product's hard 1-year requirement and made V1 effectively unsellable. I made the technical and supply case for moving to a Nordic Semiconductor nRF52832, rebuilt the firmware from scratch, and worked closely with the hardware team on the V2 design. The shipped sensor is rated for 3+ years, and units installed in late 2022 are now 3.5 years in with strong battery capacity remaining: field evidence that firmly points toward a real-world life of around 4 years.

Coming soon

The full case study is being written

The complete write-up for Motion and Light Sensor, the engineering decisions behind it, the trade-offs, and the results, is being prepared and will be published here soon. The summary above is the short version for now.

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