The pitch is absurd and the author knows it. He has six bins on multiple collection schedules, a home automation system that already tracks what's due, and a wife who would probably prefer he just set a phone reminder. Instead he built BinRange: a fixed UWB radio anchor, six battery-powered tags with custom firmware, a printed enclosure, and a Home Assistant integration that fuses ranging data with collection schedules. The answer to 'have you put the bins out?' now involves time-of-flight radio measurements accurate to two centimetres. The technical journey is the real content here. An earlier attempt with Bluetooth RSSI tags failed because signal strength is a terrible proxy for distance — walls, cars, antenna orientation, and battery voltage all corrupt the reading. UWB sidesteps this entirely by measuring propagation time rather than signal strength. The first calibrated test between two Makerfabs ESP32-WROVER/DW3000 boards returned a reading within two centimetres of a tape measure at ten metres. A later recorded test at 10.1 metres averaged 10.09 metres with a 3cm standard deviation. The author is careful to distinguish first-calibration results from real-world installed performance, which is a good sign. The hardware choices are specific and well-reasoned. The bin-side tags are KKM K4Ws running nRF52833 processors with DW3110 UWB radios and LIS3DH accelerometers, powered by chunky CR2477 coin cells. The accelerometer interrupt wakes the nRF from deep sleep only on physical movement, so a stationary bin checks in every thirty minutes while a moving bin reports every five seconds. The author's familiarity with nRF52 power management from his rlab days is doing real work here — this isn't someone reading a getting-started guide. Cost transparency is refreshing: two Makerfabs dev boards at $123.64 shipped, ten sample tags at $25 each plus jig and shipping for another $330. The author explicitly declines to calculate a payback period, which tells you everything about the project's actual justification. He also notes that the supplier's printed serial numbers on tag cases bore no relation to the embedded MAC addresses, rendering them useless for his purposes — the kind of detail that saves another builder hours of confusion. The outdoor walk test established practical limits: reliable readings to about thirty metres, intermittent beyond that, with the furthest recorded reading at 37.28 metres. A car in the path could block the signal completely. For the bin application, none of this matters — a ten-metre boundary between Home and Out is all the project needs, and it's well within the reliable range. The firmware and integration architecture is deliberately simple. The anchor publishes over MQTT, Home Assistant auto-discovers each tag as a separate device, and there's no extra server or cloud dependency. The radios keep ranging even when Home Assistant or MQTT is unavailable. The author considered an ESPHome component and decided it added nothing. He also acknowledges leaning heavily on Codex and later Astra throughout the build, treating AI as an iteration accelerator rather than claiming it did the engineering. This is a project write-up in the tradition of the best hobbyist engineering blogs: technically specific, self-aware about its own excess, generous with failure modes and practical numbers, and genuinely useful to anyone considering UWB for proximity detection. The bins are the excuse. The real subject is how UWB ranging behaves in a residential outdoor environment, documented with enough rigour to save the next person significant time.
