Emits MAVLink HEARTBEAT messages on a configurable interval.

Most MAVLink nodes (cameras, GCSes, companion computers, autopilots) must emit a HEARTBEAT roughly once per second so peers know they're alive. Without it, dynamic / peer-learning routers like the reference mavlink-router don't forward traffic to them. xmavlink itself does not emit HEARTBEATs by default; consumers traditionally built and sent their own. This module standardises that pattern.

Configuration

Set :heartbeat in the application environment for :xmavlink. If the key is unset or nil, no HEARTBEATs are emitted (backwards compatible with versions ≤ 0.6.0).

Static message

config :xmavlink,
  heartbeat: [
    interval_ms: 1000,
    message: %Common.Message.Heartbeat{
      type: :mav_type_gcs,
      autopilot: :mav_autopilot_invalid,
      base_mode: MapSet.new(),
      custom_mode: 0,
      system_status: :mav_state_active,
      mavlink_version: 3
    }
  ]

Suitable for nodes whose HEARTBEAT contents don't change at runtime (e.g. a stateless GCS).

Dynamic builder

config :xmavlink,
  heartbeat: [
    interval_ms: 1000,
    builder: {MyApp.Mavlink, :build_heartbeat, []}
  ]

The {module, function, args} tuple is invoked on every tick to produce a fresh struct. Use this when system_status, base_mode, or custom_mode should reflect application state.

Either :message or :builder is required (not both). :interval_ms is required.

First heartbeat

The first HEARTBEAT is dispatched immediately after init, so a peer-learning router admits the node within milliseconds rather than waiting up to a full interval.