The AirMate IR build package: parts, wiring, CAD, firmware and app

We have not built anything yet. This post is the package we will build from, so you can see exactly what goes into AirMate IR and tell us what to change.

What goes inside

• ESP32-C6 (Wi-Fi 6, Bluetooth and Thread) as the brain. We picked it over the ESP32-C3 because the dev kit has 8 MB of flash, enough room to measure Matter with over-the-air updates, and more spare pins.
• Hi-Link LD2410C 24 GHz radar to see moving and still people, up to about 5 m across ±60°.
• Sensirion SHT45 for room temperature (±0.1 °C typical) and humidity.
• Four 940 nm IR LEDs to send your AC’s own remote codes, and an IR receiver to learn codes from your remote.
• USB-C, 5 V. Nothing switches mains power.

One breadboard set costs about $75 in parts. We are buying three, about $271 including shared tools. The build kit page lists every part with a link to where we are buying it.

The enclosure

A 70 × 70 × 25 mm pebble in two printed parts, plus a desk stand and a 3 mm IR-transmitting window. It is written as code, so a change is one parameter away. A first review against real part sizes already moved four features: the front wall is thinner in front of the radar, the USB-C opening is higher, and the light pipe and reset hole moved clear of other parts. You can rotate and explode the real CAD on the build kit page.

The firmware and the rules

The first firmware is an ESPHome configuration that works with Home Assistant out of the box. It follows the rules we described in the plan:

• Never off when unsure. A weak still signal counts as a person.
• Empty means empty for a while: 15 minutes by default, 60 at night.
• Sleep is presence, and heat safety turns cooling back on if the room gets too hot while anyone might be there.
• Never auto-off with one button press, for guests, babies or pets.

It is written against the official documentation but has not been compiled yet. That is the first job when the dev kits arrive.

The presence model

The radar reports energy in 9 distance gates. We will record it in 10+ real rooms (empty, sleeping, reading, working, fans on, curtains moving, pets) and train a small classifier that runs on the ESP32. We tune it so it almost never calls a room empty when someone is there.

The app

Home Assistant first, Matter in production firmware, plus our own app for setup, live presence and comfort rules. You can try an interactive prototype now: walk into the simulated room, sit still, fall asleep, leave, and watch the decisions.

What we are testing first

• A very still sleeper the radar cannot see.
• The radar seeing the AC’s moving louvres.
• Long IR codes on the ESP32-C6 receiver.
• Wi-Fi range inside a small case.
• The right plastic thickness in front of the radar.

Next

Order the kits, print the enclosure and flash the firmware. Then control five real AC brands from a breadboard. If you have an unusual AC, tell us the brand and model in the AirMate IR feedback section.