Meshtastic-Android/docs/en/developer/transport.md

title, parent, nav_order, last_updated, aliases

title	parent	nav_order	last_updated	aliases
Transport	Developer Guide	5	2026-05-13	ble serial tcp radio-transport

Transport

Meshtastic communicates between the app and radio hardware through multiple transport mechanisms.

Transport Abstraction

The transport layer is abstracted through interfaces in core/network and core/ble, allowing the app to work identically regardless of the underlying connection type.

App ← RadioController → Transport (BLE | Serial | TCP)

Bluetooth Low Energy (BLE)

Module: core:ble
Platforms: Android, Desktop (JVM via Kable), iOS (planned)

The primary transport for mobile devices and also available on desktop:

• Service discovery for Meshtastic GATT services
• Characteristic-based read/write for protobuf packets
• Connection state management and automatic reconnection
• MTU negotiation for optimal packet sizes

Key Classes

• core/ble/ — BLE scanning, connection, and GATT operations
• Platform-specific implementations in androidMain and jvmMain (Kable)

USB Serial

Module: core:network
Platforms: Android (OTG), Desktop

Serial communication over USB:

• Uses usb-serial-for-android library on Android
• Direct serial port access on Desktop (JVM)
• Probe table for supported USB vendor/product IDs
• Automatic detection when USB device is connected

Key Classes

• Serial prober and transport factory in core/network
• Desktop-specific serial in desktopApp/src/main/kotlin/.../radio/

TCP/IP

Module: core:network
Platforms: Android, Desktop, iOS

Network-based transport for WiFi-enabled radios:

• TCP socket connection to radio's IP address
• Default port: 4403
• Used for development with simulated radios
• Available when BLE/USB is impractical

Transport Factory

The RadioTransportFactory interface abstracts transport creation:

interface RadioTransportFactory {
    val supportedDeviceTypes: List<DeviceType>
    fun createTransport(address: String, service: RadioInterfaceService): RadioTransport
    fun isMockTransport(): Boolean
    fun isAddressValid(address: String?): Boolean
    fun toInterfaceAddress(interfaceId: InterfaceId, rest: String): String
}

Platform-specific implementations:

• Android: Supports BLE + USB + TCP
• Desktop: Supports BLE (Kable) + USB + TCP
• iOS: Planned BLE + TCP

Connection Lifecycle

1. Discovery — Scan for available radios (BLE scan / USB detect / manual TCP)
2. Connection — Establish link to selected radio
3. Handshake — Exchange node info and configuration
4. Active — Normal message exchange
5. Disconnection — Clean teardown or error recovery

Adding a New Transport

1. Implement RadioTransport interface
2. Register in platform-specific RadioTransportFactory
3. Add connection UI in feature:connections
4. Update DI bindings for the platform

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