HID++ Reference

HID++ is Logitech’s vendor protocol for configuring mice, keyboards, and receivers over USB HID. OpenLogi speaks it directly — the same protocol Options+ uses — through the hidpp Rust crate.

Two generations

• HID++ 1.0 — a fixed set of numbered registers. Used mainly by older Unifying receivers for pairing and device enumeration.
• HID++ 2.0 — a discoverable set of features, each identified by a 16-bit ID (written 0xZZZZ, e.g. 0x2201). This is what modern devices use.

Feature discovery

A 2.0 device exposes its capabilities through two root features:

• 0x0000 root — resolves a feature ID to its runtime feature index.
• 0x0001 featureSet — enumerates every feature the device implements.

From there, OpenLogi queries individual features — device information, battery, DPI, SmartShift, and so on. See the feature index.