0x4600 · crown

The Crown feature controls the rotary crown on the MX Master series. get_info returns the hardware's CrownControlCapabilities (button, long-press, mechanized ratchet, configurable rotation timeout, short-long timeout, and double-tap speed) plus CrownSensorCapabilities (proximity, touch, tap, and double-tap gestures), together with the slot and ratchet counts per revolution. get_mode and set_mode read and write the active CrownMode: whether events are delivered over the native HID channel or diverted into HID++ (ReportingMode), the ratchet vs. free-spin choice (RatchetMode), and three configurable timings: rotation timeout, short-long press threshold, and double-tap speed, all in 10 ms steps. Every SetCrownMode field uses a zero / NoChange sentinel so individual settings can be updated without disturbing the others.

While diverted, the crown emits a single CrownEvent::Update carrying a CrownUpdate snapshot:

• rotation_state / relative_slot_rotation / relative_ratchet_rotation / speed — RotationState phase, signed delta slot and ratchet counts, and current speed in slots/s.
• proximity / touch — ActivityState lifecycle phases (Start → Active → Stop).
• gesture — CrownGesture: Tap, DoubleTap, or None.
• button — ButtonState: Inactive, Press, ShortPressActive, LongPress, LongPressActive, or Release.

Spec: Logitech HID++ 2.0 — 0x4600 crown. Used by: Typed wrapper in openlogi-hidpp.

Function reference

The CrownFeature wrapper (0x4600) exposes:

Methods

get_info, get_mode, and set_mode are async and return Result<…, Hidpp20Error>. listen is synchronous and returns an async_channel::Receiver<CrownEvent> directly.

Types

CrownInfo

Crown capabilities and hardware constants returned by get_info.

CrownControlCapabilities

Crown control capabilities, from get_info.

CrownSensorCapabilities

Crown sensor capabilities, from get_info.

CrownMode

The crown's current mode, returned by get_mode and echoed by set_mode.

SetCrownMode

Mode settings written by set_mode. Every field uses 0 / ReportingMode::NoChange / RatchetMode::NoChange as a "leave unchanged" sentinel. The rotation timeout is clipped to 0x40.

ReportingMode

How crown events are reported.

RatchetMode

The crown's ratchet mode.

RotationState

Rotation phase reported in a CrownUpdate.

ActivityState

Proximity or touch activity phase reported in a CrownUpdate.

CrownGesture

Touch gesture reported in a CrownUpdate.

ButtonState

Crown button state reported in a CrownUpdate.

Events

CrownFeature implements EmittingFeature<CrownEvent>; call listen() to receive a channel of CrownEvent values. Events are only delivered while the crown is diverted (ReportingMode::Diverted).

CrownEvent

CrownUpdate

Payload of CrownEvent::Update.

Wire format

Getter requests carry a 3-byte zero payload (call). set_mode uses a 16-byte long payload (call_long). All responses are read from the 16-byte extended payload returned by extend_payload(). Events arrive as unsolicited 16-byte messages on function index 0.

get_info (fn 0)

Request: [0x00, 0x00, 0x00]

Response (byte → field):

get_mode (fn 1)

Request: [0x00, 0x00, 0x00]

Response (byte → field):

set_mode (fn 2)

Request (16-byte long payload — bytes 5–15 are 0x00):

Response: same layout as get_mode — the device echoes the resulting active mode.

CrownEvent::Update (event fn 0)

Unsolicited event emitted while the crown is diverted:

Usage (Rust)

use hidpp::{
    device::Device,
    feature::crown::{CrownFeature, ReportingMode, RatchetMode, SetCrownMode},
};

// device: &mut Device, already created via Device::new(channel, index)
device.enumerate_features().await?;
if let Some(feat) = device.get_feature::<CrownFeature>() {
    let info = feat.get_info().await?;
    println!("slots/rev={}, ratchets/rev={}", info.slots, info.ratchets);

    // Divert crown events to HID++ and switch to ratchet mode
    let mode = feat.set_mode(SetCrownMode {
        diverting: ReportingMode::Diverted,
        ratchet_mode: RatchetMode::Ratchet,
        rotation_timeout: 0,    // leave unchanged
        short_long_timeout: 0,  // leave unchanged
        double_tap_speed: 0,    // leave unchanged
    }).await?;
    println!("active mode: {:?}", mode.diverting);

    // Receive crown events
    let rx = feat.listen();
    while let Ok(event) = rx.recv().await {
        println!("{:?}", event);
    }
}