Technical Specification

Architecture Overview

Design Principle

The application is built using Flutter and leverages the Riverpod state management framework. It interacts with ELRS hardware via a RESTful API exposed by the device's onboard WiFi module, ensuring low-latency communication and real-time state synchronization.

Data Layer

API Endpoints

The system communicates with the hardware using the following HTTP endpoints:

Method	Endpoint	Description
GET	/config	Retrieves the current device configuration in JSON format.
POST	/options.json	Updates modifiable runtime options (SSID, Password, etc.).
POST	/config	Updates core hardware parameters and PWM mappings.
POST	/reboot	Triggers a hardware reset to apply changes.

JSON Schema

The RuntimeConfig model leverages the ELRS 4.x structure, which separates parameters into three primary nodes:

• settings: Read-only hardware identifiers and version strings.
• options: Modifiable user preferences and network credentials.
• config: Low-level hardware configurations (Protocols, PWM Arrays).

Example JSON structure:

{
  "product_name": "Test RX",
  "settings": {
    "version": "1.0.0",
    "module-type": "RX"
  },
  "options": {
    "bindPhrase": "example",
    "wifi-ssid": "SSID",
    "domain": 1
  },
  "config": {
    "serial-protocol": 0,
    "pwm": [
      {"channel": 0, "mode": 5}
    ]
  }
}

State Management

The system employs a reactive architecture:

• ConfigViewModel: Manages the live connection state, heartbeat logic, and IP discovery.
• DeviceEditorViewModel: Houses the draft state of a device’s configuration, enabling multi-step edits with final “save/cancel” logic.
• FlashingController: Orchestrates firmware downloads, local binary patching, and the XH-over-HTTP upload process.

Mapping Layer

The following tables define the mapping between integer identifiers used in the API and their human-readable equivalents.

Regulatory Domains

ID	Label	Description
0	AU915	Australia/New Zealand 915MHz
1	FCC915	North American 915MHz
2	EU868	European 868MHz
3	IN866	Indian 866MHz
4	AU433	Australia 433MHz
5	EU433	European 433MHz
6	US433	North American 433MHz
7	US433-Wide	North American Wide 433MHz

Advanced Mappings

VBind (Binding Storage)

Determines how the binding phrase is stored on the device.

• 0: Persistent: Saved to flash memory (standard).
• 1: Volatile: Cleared on power cycle.
• 2: Returnable: Used for loaner gear.
• 3: Administered: Used in multi-pilot fleet environments.

Persistence Layer

The system implements a dual-layer persistence strategy:

• SharedPreferences: Utilized via PersistenceService for non-sensitive data such as WiFi SSIDs and general app preferences.
• FlutterSecureStorage: Used for sensitive data, including Binding Phrases and WiFi Passwords, ensuring encryption at the OS level.