Breadcrumbs is a wireless emergency communication system designed for hikers and outdoor explorers who venture into areas with no cellular service or Wi-Fi coverage.
By dropping small ESP32 “crumb” nodes along a trail, users can create a relay network that forwards messages hop-by-hop back to a gateway device connected to the internet.
Getting lost or injured in remote areas can quickly become dangerous when there is no signal to call for help.
Breadcrumbs provides a lightweight, portable way to extend connectivity into the wilderness using low-cost microcontrollers, enabling hikers to send SOS messages and find their way back safely.
- 📡 Creates an off-grid relay network using ESP32 nodes dropped along a hiking path
- 🛰️ Relays messages hop-by-hop until reaching a gateway node with internet access
- 🆘 Supports emergency communication like SOS alerts
- 🔦 Includes guidance features such as:
- detecting when a node is picked up
- beeping/blinking the next node to drop
- lighting a return path back to safety
- The hiker carries multiple ESP32 “crumb” devices in a pouch.
- As they walk deeper into the woods, they drop crumbs periodically.
- The pouch (Bread) uses ESP-NOW to measure signal strength (RSSI) of the last-dropped crumb (crumbs send periodic beacons). When the signal drops below a threshold for a short time, it tells the next crumb to beep/blink so the hiker knows which one to drop.
- Each crumb automatically connects to its nearest neighbor and forms a relay chain.
- Messages are forwarded node-to-node using ESP-NOW, a low-power peer-to-peer Wi-Fi protocol.
- When the message reaches the gateway node near connectivity, it is forwarded to the internet (e.g., Discord webhook, SMS, or server).
ESP32 nodes forward packets across multiple hops without requiring routers or infrastructure.
Each crumb can detect when it has been removed from the pouch using a Hall effect sensor + magnet system.
The pouch measures the last-dropped crumb’s signal strength (RSSI) from ESP-NOW packets (crumbs send periodic beacons). When the signal stays below a configurable threshold (e.g. -78 dBm) for a short period, the pouch triggers the next crumb to beep/blink—so you drop based on how weak the signal gets, not on a fixed timer.
When it’s time to drop the next crumb, that crumb beeps or blinks so the user knows which one to take from the pouch.
Users can send SOS alerts that propagate through the breadcrumb trail back to safety.
Crumbs can blink sequentially to guide hikers back along the original path.
- ESP32 DevKit v1
- ESP-NOW (wireless packet relay + RSSI from received packets for drop-by-signal-strength timing; crumbs send periodic beacons)
- Hall effect sensors + magnets (pickup detection)
- Gateway node with Wi-Fi hotspot/internet forwarding
- Optional Discord/Telegram webhook integration
Each node is battery-powered for outdoor portability.
Recommended configurations:
- 4×AA battery pack into VIN
- LiPo/Li-ion battery with voltage regulation
- USB power bank for prototyping/demo
- Hiking in remote areas with no signal
- Emergency SOS relay system
- Backtracking and navigation assistance
- Outdoor mesh sensor network extensions
- Upgrade from ESP-NOW to ESP-MESH or LoRa for longer range
- Full phone-to-internet routing through mesh
- GPS logging for breadcrumb mapping
- Encrypted messaging and authentication
- Automatic drop-spacing using BLE RSSI (implemented in Bread/pouch firmware)
Built for MakeUofT as a hackathon project exploring off-grid communication, embedded networking, and wilderness safety.
(Add photos, wiring diagrams, and a short demo video link here)