# `MAVLink2.Command`
[🔗](https://github.com/isaiahdw/mavlink2/blob/v0.1.0/lib/mavlink2/command.ex#L1)

MAVLink's command protocol: a `COMMAND_LONG` or `COMMAND_INT` to a
target, answered by `COMMAND_ACK`.

    MAVLink2.Command.long(link, {1, 1}, :mav_cmd_component_arm_disarm, [1.0])
    #=> {:ok, :mav_result_accepted, %MyDialect.CommandAck{...}}

The link's dialect must have the messages (`common.xml` does). `target`
is `{sysid, compid}`; compid 0 accepts the reply from any component of the
system. `command` is a `MAV_CMD` entry atom or its value.

With no ack in `:timeout`, the command is sent again, up to `:retries`
more times; a `COMMAND_LONG` sent again has its `confirmation` counted up.
An ack of `MAV_RESULT_IN_PROGRESS` stops the resending: each one goes to
`:on_progress`, and the wait for the final ack restarts at
`:progress_timeout`. `cancel/3` asks the target to stop a long-running
command.

Options:

| | |
| --- | --- |
| `:timeout` | ms to wait for an ack before sending again (default 1000) |
| `:retries` | times to send again (default 3) |
| `:progress_timeout` | ms to wait after an in-progress ack (default 5000) |
| `:on_progress` | called with each in-progress ack |

Returns `{:ok, result, ack}`, with `result` the `MAV_RESULT` entry atom
(`:mav_result_accepted`, `:mav_result_denied`, ...) and `ack` the decoded
`COMMAND_ACK`, or `{:error, :timeout}`.

# `cancel`

```elixir
@spec cancel(GenServer.server(), MAVLink2.target(), atom() | integer()) ::
  :ok | {:error, term()}
```

Sends `COMMAND_CANCEL` for a long-running `command` the target is
executing. It is not acked: the `long/5` or `int/5` call waiting on the
command returns with the target's final ack, `:mav_result_cancelled` if
it cancelled. A target that cannot cancel carries on, and one with
nothing running ignores it. The dialect must have `COMMAND_CANCEL`
(current `common.xml` does).

# `int`

```elixir
@spec int(
  GenServer.server(),
  MAVLink2.target(),
  atom() | integer(),
  keyword(),
  keyword()
) ::
  {:ok, atom() | integer(), struct()} | {:error, term()}
```

Sends `COMMAND_INT`. `fields` are its fields other than the target and
command: `:frame` (a `MAV_FRAME` atom or value), `:param1`..`:param4`,
`:x`, `:y` (integers, degrees × 10^7 for a global frame), `:z`,
`:current`, `:autocontinue`; each defaults to 0.

# `long`

```elixir
@spec long(
  GenServer.server(),
  MAVLink2.target(),
  atom() | integer(),
  [number()],
  keyword()
) ::
  {:ok, atom() | integer(), struct()} | {:error, term()}
```

Sends `COMMAND_LONG` with up to seven `params` (the rest 0.0).

---

*Consult [api-reference.md](api-reference.md) for complete listing*