OpenLogi0x0001 · featureSet
Enumerate all features a device implements — read the count and look up each feature's ID, type flags, and version by index.
Enumerates the features a device implements. getCount() returns how many
features there are; getFeatureId(index) returns the ID (and type flags —
hidden, obsolete, etc.) at each index.
Together with 0x0000 root this lets a client
discover a device's full capability set without prior knowledge of the model.
Spec: Logitech HID++ 2.0 — x0001 featureSet. Used by: capability discovery.
Function reference
The FeatureSetFeature wrapper (0x0001) exposes:
Methods
| Function | HID++ fn | Signature | Returns |
|---|---|---|---|
count | 0 | () | u8 |
get_feature | 1 | (index: u8) | FeatureInformation |
All methods are async and return Result<…, Hidpp20Error>.
Types
FeatureInformation
Information about a specific feature as returned by get_feature.
| Field | Type | Description |
|---|---|---|
id | u16 | The protocol ID of the feature. |
typ | FeatureType | The type flags of the feature. |
version | u8 | The latest supported version of the feature. Added in feature version 1; 0 for older versions. Multi-version features are always backwards compatible as long as the feature ID does not change. |
FeatureType
A bitfield describing some properties of a feature. Each field corresponds to one flag bit in the type byte returned by the device.
| Field | Bit | Description |
|---|---|---|
obsolete | 7 | Feature replaced by a newer one but still advertised so that older software can support it. |
hidden | 6 | Should not be known, managed, or used by end-user configuration software; the host should ignore it. |
engineering | 5 | A hidden feature disabled for user software, used for internal testing and manufacturing. |
manufacturing_deactivatable | 4 | Manufacturing feature that can be permanently deactivated; usually also hidden and engineering. Added in feature version 2; false on older versions. |
compliance_deactivatable | 3 | Compliance feature that can be permanently deactivated; usually also hidden and engineering. Added in feature version 2; false on older versions. |
Wire format
Both functions use a 3-byte short-report request payload. Responses are read from the 16-byte extended payload (extend_payload(), bytes 0–15; unused trailing bytes are zero-padded).
count (fn 0)
Request: [0x00, 0x00, 0x00] (no parameters)
Response (byte → field):
| Byte | Field | Notes |
|---|---|---|
| 0 | count: u8 | Number of features supported by the device, excluding the root feature (index 0). |
get_feature (fn 1)
Request: [index, 0x00, 0x00] — index is the 1-based feature table index (must not be 0).
Response (byte → field):
| Byte | Field | Notes |
|---|---|---|
| 0 | id high byte | Combined with byte 1 as (payload[0] as u16) << 8 | payload[1] as u16. |
| 1 | id low byte | See above. |
| 2 | typ byte | Decoded as a FeatureType bitfield: bit 7 = obsolete, bit 6 = hidden, bit 5 = engineering, bit 4 = manufacturing_deactivatable, bit 3 = compliance_deactivatable. |
| 3 | version: u8 | Latest supported version of the feature; 0 for feature version 0 devices. |
Usage (Rust)
use std::sync::Arc;
use hidpp::{device::Device, feature::feature_set::FeatureSetFeature};
// chan: Arc<HidppChannel>, device_index: u8 — obtained from a receiver walk.
let mut device = Device::new(Arc::clone(&chan), device_index).await?;
// High-level: enumerate all features and register implementations.
if let Some(features) = device.enumerate_features().await? {
for info in &features {
println!("feature 0x{:04x} version={} hidden={}", info.id, info.version, info.typ.hidden);
}
}
// Low-level: use FeatureSetFeature directly after enumeration has registered it.
if let Some(feat) = device.get_feature::<FeatureSetFeature>() {
let count = feat.count().await?;
for i in 1..=count {
let info = feat.get_feature(i).await?;
println!(" [{i}] id=0x{:04x} obsolete={}", info.id, info.typ.obsolete);
}
}