Zicada is a DIY Zigbee sensor based on Nordic’s nRF52840 SoC. It combines a temperature and humidity sensor with a hall effect switch, making it suitable for both climate and door/window monitoring. Zicada is optimized for ultra-low power consumption, running at just 6µW in standby. This allows it to operate on a rechargeable AAA battery for 2 years or longer. It is fully compatible with Home Assistant (ZHA) and Zigbee2MQTT.

Project links:
https://hackaday.io/project/204509
https://github.com/CoretechR/Zicada
https://www.youtube.com/watch?v=TRaUVJfP1CE