Traffic Light 🚦 - companion app

Mobile app for Traffic Light projet.

Controls a physical traffic light (green, orange, red lamps) from your phone.

The light works through modes: named, looping sequences of steps (a combination of lamps + duration). The app lets you list, launch, create, edit and delete these modes on the device.

Running the app

npm install
npx expo start

Scan the QR code with the Expo Go app (iOS or Android).

Simulation mode vs Wi-Fi

By default, the app runs in simulation mode: commands are printed to the console, no hardware required.

To control a real light over Wi-Fi, create a .env file at the root:

EXPO_PUBLIC_LIGHT_MODE=wifi

Then enter the light's IP address in the app's Settings screen.

Firmware HTTP API

The app talks to the ESP32-C3 through a binary API (little-endian). The source of truth is services/protocol.ts, aligned with the firmware's C code (main/modes/).

Action	Method	URL	Body
List the modes	GET	http://<IP>/get_modes	(empty)
Active mode	GET	http://<IP>/get_mode	(empty)
Firmware version	GET	http://<IP>/version	(empty)
Command on a mode	POST	http://<IP>/command	binary packet

The body of POST /command is [ command_id : uint8 ] [ payload ]:

command_id	Action	Payload
1	set (activate)	[ name_len u16 ] [ name ]
2	add	[ name_len u16 ] [ name ] [ loop u8 ] [ nb_steps u16 ] [[ mask u8 ][ duration u32 ] …]
4	delete	[ name_len u16 ] [ name ]
5	edit	[ name_len u16 ] [ name ] [ loop u8 ] [ nb_steps u16 ] [[ mask u8 ][ duration u32 ] …]

mask is a combination of lamp bits: green = 0x01, orange = 0x02, red = 0x04 (0 = off). duration is in milliseconds. Limits: name ≤ 100 bytes, ≤ 10 steps per mode.

The app polls GET /get_mode every 5 s (heartbeat) to track the active mode — which can change on the light side via the physical button — and to infer the connected / disconnected state.

The legacy direct JSON endpoints (/lampe, /allumer, /eteindre) are inherited and outside the scope of the current mode-based firmware.

Running the tests

npm test

The tests cover:

• the binary protocol (services/protocol.ts): packet encoding/decoding, lamp masks, duration conversions;
• the playback engine (services/playbackEngine.ts): step progression, looping, pause, resume, stop.

Screenshots