Changes

This release migrates all of our firmwares from Silicon Labs' older Gecko SDK to the newer Simplicity SDK. All ZWA-2 firmwares are now included in the firmware builder and can be built alongside firmwares for the Yellow, ZBT-1, and ZBT-2.

General

• Every firmware is now built with Simplicity SDK 2026.6.1. Zigbee was the last holdout on Gecko SDK.
• The ZWA-2 controller and OTW bootloader are now built and released from this repository, using the same manifests and tooling as every other adapter.

Zigbee

Firmware version 9.1.1.0, up from 7.5.1.0.

• Built with EmberZNet 9.1 from Simplicity SDK 2026.6.1, up from Gecko SDK 4.5.0.
• Added Zigbee 4.0 support. This is fully backwards compatible with Zigbee 3.0 and 1.2.
• Sending a message now takes a single request instead of up to three, reducing latency. ZHA in Home Assistant Core 2026.7.0+ will do this automatically.
• Increased network table sizes. On the ZBT-2 the route and source route tables hold 254 entries, the address table 128, and up to 128 messages can be in flight at once, with a larger packet buffer heap. On the ZBT-1 and Yellow, 64 messages can be in flight and the address table holds 32 entries.
• Increased the serial receive buffer from 128 to 512 bytes.
• Fixed an off-by-one bounds check in the experimental manual source routing command.

Thread

Firmware version 3.1.1.0, up from 2.7.2.0.

• Built with OpenThread 3.1 from Simplicity SDK 2026.6.1, up from Simplicity SDK 2025.6.2.
• Added a watchdog that resets the adapter if the firmware gets stuck.
• Fixed the serial link locking up when the host stopped reading while hardware flow control was enabled (ZBT-1 and Yellow). Transmits now give up after a short bounded wait and drop the byte, so the adapter keeps running and the host can recover.
• Doubled the host transmit buffer from 2048 to 4096 bytes, reducing dropped frames when a burst of network traffic arrives at once.
• Fixed a Green Power packet filter that misclassified zero-payload frames by reading past the end of the frame.

Z-Wave

Controller firmware version 1.3.1, bootloader version 3.2.1.

• Built with Simplicity SDK 2026.6.1 and Z-Wave SDK 8.1.1, up from Simplicity SDK 2025.12.1 and Z-Wave SDK 8.0.0.
• Fixed an issue where the radio could turn off after a single received frame. This affected some controllers migrated from a 500 series stick, where the listening flag in the controller's own node info was left unset.
• Fixed a transmission stall that could occur under LBT/CSMA.
• Fixed fragmented beam handling for the Japanese region.
• Restored runtime Image Rejection calibration.
• The bootloader version and capabilities can now be read while the application is running.

What's Changed

• Add an intermediate CI step that removes buggy status propagation by @puddly in #174
• Parallel download stages with checksumming by @puddly in #175
• Migrate build container to the new slt tool by @puddly in #178
• Switch to Box64 for slt emulation on ARM64 by @puddly in #179
• Revert "Switch to Box64 for slt emulation on ARM64" by @puddly in #180
• Use native conan package to speed up toolchain installation by @puddly in #181
• feat: build ZWA-2 controller firmware by @AlCalzone in #187
• Patch Z-Wave SDK to coexist with Simplicity SDK DMADRV by @puddly in #188
• Clean up Dockerfile and and slim down image by @puddly in #201
• Fix Zigbee XNCP manual source route bounds check by @TheJulianJES in #202
• Simplicity SDK 2026.6.0 by @puddly in #205
• Increase OPENTHREAD_CONFIG_NCP_TX_BUFFER_SIZE from 2048 to 4096 by @puddly in #208
• Add OpenThread RCP watchdog by @puddly in #207
• Push release assets to a separate branch for CORS by @puddly in #195
• Update README to include ZBT-2 by @HarvsG in #206
• Consolidated unicast sending API by @puddly in #209
• Update firmware changelogs by @puddly in #210
• Bump all manifests to Simplicity SDK 2026.6.1 by @lboue in #212
• Replace slt environment with manual dependency management by @puddly in #214
• Include all known changelog entries in manifest.json by @puddly in #213
• Replace commander with pygbl and clean up build_project.py by @puddly in #215
• Add bootloader info Serial API command for ZWA-2 by @AlCalzone in #218
• fix: work around missing listening flag in controller node info by @AlCalzone in #219
• Add ZWA-2 bootloader manifest by @AlCalzone in #216

New Contributors

• @TheJulianJES made their first contribution in #202
• @HarvsG made their first contribution in #206
• @lboue made their first contribution in #212

Full Changelog: v2026.01.11-beta2...v2026.08.18-beta1