Receivers

A receiver is the USB dongle that wireless Logitech devices pair to. OpenLogi detects the receiver on its USB/HID channel, then enumerates the devices paired to it.

Unlike device features (which use HID++ 2.0), receivers are driven through HID++ 1.0 registers and are always addressed at device index 0xFF (RECEIVER_DEVICE_INDEX). They are identified purely by their USB vendor/product ID; openlogi-hidpp's receiver::detect() matches the channel's VID/PID against the known sets and returns a Receiver.

Detection

receiver::detect(chan) returns Some(Receiver) for a known dongle, or None otherwise.

The Lightspeed dongles bundled with G-series devices answer the same HID++ 1.0 registers as Unifying, so they are detected, enumerated, routed, and paired through the Unifying code path; only the user-facing name differs (Lightspeed Receiver). C53F is the nano receiver of wireless mice such as the G305, verified against a G305 (paired device wpid 0x4074); C547 ships with newer devices such as the G915 keyboard and the G502 X LIGHTSPEED, verified against a G915 (wpid 0x407c). C539 is the Lightspeed gaming receiver, listed with the Unifying PIDs because it is routed as one. C537 is the Nano receiver bundled with the G602; it answers the same enumeration and pairing-information registers, so it routes as a Unifying receiver.

Common API

The Receiver enum wraps the concrete receiver kinds and exposes the shared surface:

Errors surface as ReceiverError: UnknownReceiver, or a wrapped HID++ 1.0 Protocol error.

Logi Bolt

The current Logitech receiver. Bolt is BLE-based, pairs up to 6 devices, and authenticates new devices with a passkey before pairing. bolt::Receiver exposes:

Pairing flow

1. discover_devices(Some(secs)) — the receiver emits Event::DeviceDiscoveryDeviceDetails (carrying the device address, kind, wpid, authentication) and Event::DeviceDiscoveryDeviceName for each nearby device.
2. pair_device(slot, address, authentication, entropy) — entropy sets passkey complexity (for mice, the number of left/right clicks the user must enter).
3. The receiver completes pairing and emits Event::DeviceConnection.

Events (bolt::Event)

DeviceKind covers Keyboard, Mouse, Numpad, Presenter, Remote, Trackball, Touchpad, Tablet, Gamepad, Joystick, Headset (plus Unknown).

Unifying

The previous-generation receiver. Unifying pairs up to 6 devices over the proprietary Unifying / DJ protocol; once addressed by their slot index, paired devices speak HID++ 2.0. unifying::Receiver exposes:

Enumerating paired devices (Rust)

use std::sync::Arc;

use hidpp::{
    channel::HidppChannel,
    receiver::{self, Receiver},
};

// chan: Arc<HidppChannel> bound to the receiver's HID interface.
let Some(rx) = receiver::detect(Arc::clone(&chan)) else {
    return; // not a known Logitech receiver
};
println!("{} — {}", rx.name(), rx.get_unique_id().await?);

match rx {
    Receiver::Bolt(bolt) => {
        for dev in bolt.collect_paired_devices().await? {
            // dev: bolt::DeviceConnection — one paired device
            let _ = dev;
        }
    }
    Receiver::Unifying(uni) => {
        let events = uni.listen();
        uni.trigger_device_arrival().await?; // re-fires DeviceConnection events
        while let Ok(event) = events.recv().await {
            // handle unifying::Event::DeviceConnection { .. }
            let _ = event;
            break;
        }
    }
    _ => {}
}

No receiver

Bluetooth-direct and wired devices enumerate as their own inventory; no receiver involved. See Connect a device.