Zigbee 4.0 and the Suzi extension were announced by the CSA around November 2025. The CSA's features deep-dive document, dated 27 October 2026, is the date of the document, not the date the standard was announced.
Summary in 3 lines
The CSA announced Zigbee 4.0 and Suzi around November 2025, according to media reports such as CNX Software (19 Nov 2025). Suzi is a long-range sub-GHz mesh extension supporting 800 MHz (Europe) and 900 MHz (North America). The technical details below come from news reports and CSA pages that could be opened, not from the full specification.
Timeline: when it was announced and when the document is dated
The announcement of Zigbee 4.0 and Suzi came around November 2025, according to reports from CNX Software (19 Nov 2025), CEPro and Microcontroller Tips. Later, the CSA published a features deep-dive document (Zigbee 4.0 Features Deep Dive) dated 27 October 2026. We saw it listed on the CSA newsroom but could not open the source PDF, so we did not use the content of the document itself and relied only on verifiable news reports. The 27 October 2026 date is therefore the date of the document, not the date of the event, and we are not saying Zigbee 4.0 was announced this week.
Suzi: a sub-GHz extension for long range
According to the reports, Suzi is a long-range sub-GHz mesh extension of Zigbee that supports the 800 MHz (Europe) and 900 MHz (North America) bands. In addition, Zigbee 4.0 is reported to combine the Zigbee architecture with Smart Energy in a single network. We do not have confirmed information on whether Suzi's frequency bands can be used legally in Thailand, so anyone interested should check before planning.
Zigbee Direct, reliability and battery saving
According to the reports, Zigbee Direct moves from optional to required, allowing devices to be set up and controlled over BLE without a hub. On reliability, network-level retries become standard, along with APS acks. CSL (sleepy-to-sleepy) helps save battery on devices that sleep most of the time.
Security and compatibility
The security features named in the reports are Dynamic Link Key, Device Interview, Restricted Mode, Secured Channel and Advanced Frame Counter Synchronization. According to the reports, Zigbee 4.0 is backward compatible with existing Zigbee devices, which the reports put at more than 1 billion units. That figure comes from the reports and is not one we verified ourselves.
How this relates to TMRX
The TMRX website lists the XIAO ESP32C6 board, which according to the product information supports 802.15.4 (Zigbee), Wi-Fi 6 and BLE 5.0 and is listed as Matter/Thread-ready. We are not saying this board supports Zigbee 4.0 or Suzi, because we have no confirmed information on that. If you want to experiment with Zigbee, check the specifications and supported software with the manufacturer before planning.
Sources
CSA — Zigbee 4.0 Features Deep Dive — dated 27 October 2026 (source PDF could not be opened) CNX Software — https://www.cnx-software.com/2025/11/19/zigbee-4-0-introduces-suzi-sub-ghz-connectivity-and-security-enhancements/ — 19 November 2025 CEPro — https://www.cepro.com/news/zigbee-enters-the-long-range-game-with-4-0-and-suzi-launches/623527 — 2025 (publication date unknown) Microcontroller Tips — https://www.microcontrollertips.com/zigbee-4-0-adds-800-900-mhz-and-new-security-features/ — 2025 (publication date unknown)
