ESP32 Wifi Light Switch Custom Build
A single battery-powered button that talks straight to the light over WiFi — press it, and it's on before you've let go. No hub. No app. No subscription.
The problem
The light in question is a short walk from the room I actually spend time in. Running a hub, a broker, or a home-automation server just to flip one switch is a lot of always-on infrastructure for a one-bit problem — one more thing that needs power, updates, and attention to keep working. I wanted a button I could put anywhere in the house, on a battery, that would last years and just work the instant it was pressed.
How it works
The button spends its entire life in deep sleep, drawing almost nothing, until a physical press wakes it. What happens next is the whole design problem:
Deep sleep, radio fully off, drawing microamps for months on end.
A press is the only thing that wakes it — no polling, nothing listening.
Joins the home WiFi directly. No bridge, no intermediary device.
Checks the light's current state, then sets it explicitly — safe to retry if the network hiccups.
Drops the connection and goes straight back to sleep. No idle listening in between.
What it does today
Measured on the fast path, end to end — press felt, light already changed by the time you'd notice.
Modelled on a single 3000 mAh cell at 2 on/off cycles a day — dominated by standby power rather than the brief moments it's awake.
Talks directly to the light over the home network. Nothing else has to be running for it to work.
Reads the light's state before acting, rather than blindly toggling — a retried or duplicated attempt can never leave it in the wrong state.
An onboard LED confirms a press was received and shows exactly how the request went — no phone, no app, no second device to check.
A press that lands while it's already mid-action isn't lost — it's picked up and actioned on the same wake, not dropped on the floor.
Each press reports its own response time back to the light's own dashboard — real numbers from real use, not just a bench estimate.
Checks in every 8 hours, even without a press, so a dying cell shows up ahead of time — instead of the button just quietly stopping one day.
What's next
This started as a personal fix for one light — the parts below are what's currently being prototyped to make the same idea easy for someone else to actually use, not committed features on a fixed date.
A guided setup mode — join your WiFi and pick the light from a list, no code to edit.
Automatic discovery of the target device on your network, instead of typing in an address.
A 3D-modeled, 3D-printed case with embedded neodymium magnets — so it sticks straight onto metal surfaces, no mounting hardware needed.