Matter ICD (Intermittently Connected Device) Implementation

Overview

The ICD Management Cluster (0x0046) is always enabled in Tasmota's Matter implementation per Matter 1.4.1 specification. Since Tasmota devices are mains-powered WiFi devices that are always connected, the cluster reports the device as a basic SIT (Short Idle Time) device without optional features.

What is ICD?

ICD (Intermittently Connected Device) is a Matter feature that allows devices to communicate their availability patterns to controllers. Per Matter 1.4.1 spec section 9.17:

• SIT (Short Idle Time): Devices with idle periods < 15 seconds - used for always-on devices
• LIT (Long Idle Time): Devices with idle periods >= 15 seconds - used for battery-powered sleepy devices

Tasmota devices use SIT mode since they are always connected via WiFi.

Implementation Details

ICD Management Cluster (0x0046)

The ICD Management Cluster is always present on the Root endpoint (endpoint 0).

Per Matter 1.4.1 spec section 9.17.4, the cluster has optional features:

• CIP (Check-In Protocol Support): For LIT devices to notify clients
• UAT (User Active Mode Trigger): For user-triggered wake
• LITS (Long Idle Time Support): For LIT operation mode
• DSLS (Dynamic SIT/LIT Support): For switching between modes

Tasmota implements none of these optional features (FeatureMap = 0x00) since it's an always-on device.

Supported Attributes (per spec section 9.17.6)

Attribute	ID	Type	Value	Conformance	Description
IdleModeDuration	0x0000	uint32	1	Mandatory	1 second (minimum per spec)
ActiveModeDuration	0x0001	uint32	300	Mandatory	300ms (spec default)
ActiveModeThreshold	0x0002	uint16	300	Mandatory	300ms (spec default)

Attributes NOT Implemented (require optional features)

Attribute	ID	Conformance	Reason
RegisteredClients	0x0003	CIP	Requires Check-In Protocol
ICDCounter	0x0004	CIP	Requires Check-In Protocol
ClientsSupportedPerFabric	0x0005	CIP	Requires Check-In Protocol
UserActiveModeTriggerHint	0x0006	UAT	Requires User Active Mode Trigger
UserActiveModeTriggerInstruction	0x0007	UAT	Requires User Active Mode Trigger
OperatingMode	0x0008	LITS	Requires Long Idle Time Support
MaximumCheckInBackoff	0x0009	CIP	Requires Check-In Protocol

Cluster Configuration

• Cluster Revision: 3 (Matter 1.4.1)
• Feature Map: 0x00 (no optional features)

mDNS Advertisement

Per Matter 1.4.1 spec section 4.3.4, the following TXT records are included:

Key	Value	Description
SII	500	SESSION_IDLE_INTERVAL in ms (spec default)
SAI	300	SESSION_ACTIVE_INTERVAL in ms (spec default)

Note: The ICD key is NOT advertised because per spec: "The key SHALL NOT be provided by a Node that does not support the ICD Long Idle Time operating mode."

Files Modified

1. Matter_Plugin_1_Root.be

   • ICD Management Cluster (0x0046) with attributes [0,1,2]
   • Fixed attribute values per spec defaults

2. Matter_Plugin_0.be

   • Cluster revision 3 in CLUSTER_REVISIONS
   • Feature map 0x00 in FEATURE_MAPS

3. Matter_z_Commissioning.be

   • SII/SAI values in mDNS PASE announcement (spec defaults)

Why This Implementation?

1. Spec Compliance: Only mandatory attributes are implemented; optional features (CIP, UAT, LITS) are not needed for always-on devices

2. Simplicity: No configuration needed since Tasmota devices are always-on WiFi devices

3. Controller Compatibility: Controllers can read the ICD cluster to understand the device is always reachable

Spec References

• Matter 1.4.1 Core Specification
• Section 9.17: ICD Management Cluster
• Section 4.3.4: Common TXT Key/Value Pairs
• Section 4.13.1: Session Parameters

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Implementation Date: January 2026 Based on Matter 1.4.1 Core Specification