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The problem
E-waste collection runs on fixed routes: trucks visit every bin on schedule whether it is empty or overflowing, wasting fuel on empty stops while full bins spill hazardous material. The missing piece is fill-level visibility. This project puts a low-power sensor node on each bin. An HC-SR04 ultrasonic module mounted over the bin measures the distance to the waste surface; the ESP32 takes the median of 5 pings, converts it to fill % = (bin depth − distance) / bin depth, and reports every 15 minutes — or immediately when the lid closes. Between readings the node sleeps at roughly 18 µA (design target), powered by a small solar panel charging the battery, so it runs maintenance-free. A local LCD shows the live state (FILL: 72%, Dist: 3.8 cm). The BinWatch dashboard shows the whole fleet — 12 bins in the demo — with fill bars, node diagnostics, collection alerts ("BIN-04 · City Mall reached 91% — added to today's route"), and a 14-day fill history per bin.
Ultrasonic ranger mounted above the bin opening.
Follow the working sequence
How it works
- The HC-SR04, mounted on a stand above the bin opening, fires 5 ultrasonic pings; the ESP32 takes the median distance to reject outliers from uneven waste surfaces.
- Fill % is computed as (bin depth − median distance) / bin depth; the local LCD updates to show the fill % and raw distance.
- The node reports on a 15-minute schedule, and additionally wakes to report immediately when the lid-close switch triggers.
- Between readings the ESP32 enters deep sleep (~18 µA design target); the solar panel trickle-charges the battery, with charge voltage shown in diagnostics.
- The dashboard renders the fleet: fill bars per bin, 14-day history on click, node diagnostics, and alerts when bins cross the 85% collection threshold.
- Collection alerts feed a daily route — the demo shows route distance saved (34 km) and e-waste logged at the depot (61 kg) as the operational payoff.
Tech stack:
- ESP32 firmware (deep sleep, median filtering)
- HC-SR04 ultrasonic sensor
- Solar panel + battery charging
- Lid-close switch
- 16×2 LCD (local fill display)
- Fleet dashboard (fill bars, history, diagnostics)
- MQTT/HTTP telemetry
- Git
| Parameter | Value |
|---|---|
| Controller | ESP32 DevKit v1 |
| Fill sensor | HC-SR04 ultrasonic (datasheet 2 cm–400 cm range) |
| Fill formula | (bin depth − median distance) / bin depth, median of 5 pings |
| Reporting | Every 15 min + immediate on lid-close (design behavior) |
| Power | Solar panel + battery; deep sleep ~18 µA (design target) |
| Local display | LCD: fill %, distance in cm |
| Dashboard | Fleet fill bars, 14-day history, diagnostics, alerts |
| Demo fleet | 12 e-waste bins (Railway Stn, College, Library, City Mall, …) |
Project features
- [Ultrasonic fill sensing] HC-SR04 measures distance to the waste surface; fill % computed as (bin depth − distance) / bin depth from the median of 5 pings per reading.
- [Lid-close reporting] Readings every 15 minutes plus an immediate report when the lid closes — the moment the fill level actually changed.
- [Solar + deep sleep] Small solar panel with charging; node sleeps between readings at ~18 µA deep-sleep current (design target) for maintenance-free operation.
- [Local LCD] Live fill % and distance on the node's display (E-WASTE BIN MONITOR, FILL: 72%, Dist: 3.8 cm).
- [Fleet dashboard] 12 bins with live fill bars (green/yellow/red), click any bin for its 14-day fill history.
- [Node diagnostics] Ultrasonic health, lowest battery, solar input voltage, deep-sleep current and worst RSSI — the maintenance view for the whole fleet.
- [Collection alerts] Bins crossing 85% are auto-added to today's collection route; fast-filling bins get watch warnings.
What is included
- Complete ESP32 bin-node prototype (HC-SR04, solar panel, LCD, lid switch, wiring diagram)
- Low-power firmware (deep sleep, median filtering, telemetry)
- Fleet dashboard (fill bars, history, diagnostics, collection alerts)
- Installation guide (sensor mounting, bin-depth calibration, solar sizing)
- Project report PDF (background, ultrasonic theory, power budget, methodology)
- PPT presentation for final review
- Viva Q&A preparation document (HC-SR04, deep sleep, solar, MQTT)
Limitations & prerequisites
- Ultrasonic readings depend on a reasonably flat waste surface; tangled cables and large items create uneven surfaces — the median-of-5 filter mitigates but does not eliminate this.
- The ~18 µA deep-sleep figure is a design target for the power budget; the built node's achieved sleep current depends on the regulator and peripherals used.
- The dashboard figures (fleet fills, route savings, 61 kg logged) are illustrative simulation data from the demo app, not measurements from deployed bins.
- The HC-SR04's 2 cm minimum range means very full bins read at the sensor's blind zone; the bin-depth calibration must account for this offset.
- Solar charging assumes reasonable daylight at the bin location; shaded indoor bins need mains or larger batteries.
Frequently Asked Questions
How is fill level measured?
An HC-SR04 ultrasonic sensor above the bin measures the distance to the waste surface; fill % = (bin depth − distance) / bin depth, using the median of 5 pings to reject outliers from uneven waste.
Why report on lid-close?
The fill level only changes when waste is added — the lid closing is that moment. Immediate reporting on lid-close keeps the dashboard current without wasting power on pointless 15-minute reads of an unchanged bin.
How does it stay powered?
A small solar panel charges the battery while the ESP32 deep-sleeps (~18 µA design target) between readings — no mains wiring at the bin.
What does the dashboard do with the data?
Fleet fill bars with 14-day history per bin, node diagnostics (battery, solar, signal), and collection alerts: bins over 85% are auto-added to today's route so trucks skip empty stops.
How accurate is ultrasonic fill sensing?
As a design target, ±1–2 cm on a flat surface (HC-SR04 resolution); uneven e-waste surfaces add noise, which is why the firmware uses median-of-5 filtering and the bin depth is calibrated at install.
Is this project suitable for a final-year project?
Yes — for IoT & Embedded, Electronics and Computer Science programs. It combines ultrasonic sensing, ultra-low-power design, solar energy and a fleet dashboard around a real smart-city waste problem. Suitable for B.E./B.Tech final-year projects in IoT & Embedded Systems, Electronics and Computer Science.
Components & software requirements
- ESP32 firmware (deep sleep, median filtering)
- HC-SR04 ultrasonic sensor
- Solar panel + battery charging
- Lid-close switch
- 16×2 LCD (local fill display)
- Fleet dashboard (fill bars, history, diagnostics)
- MQTT/HTTP telemetry
- Git
Delivery information
Built-to-order project. Delivery timeline is shared after order confirmation based on current queue.
Support terms
Complete documentation, setup guide, and viva preparation included. Support for setup and explanation provided.
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