From Gareth Halfacree on Hackster:

Alvaro Prieto Walks Through a Year of Chaac Weather Station Designs, Upgrades, and Enhancements

Alvaro Prieto has published a write-up of his latest weather station board, the Chaac v4.0, which adds Bluetooth connectivity to his existing XBee-based design.

The Chaac project has been ongoing for some time: Prieto documented his original efforts to build a weather station a year ago, walking through a range of improvements that went from an nRF52-based Bluetooth Low Energy prototype through to a breakout board for the Nucleo development board, and the integrated Chaac board versions 1.0 through 1.2 — the latter adding in solar panel voltage monitoring.

In the year since, Prieto has been working on upgrading the Chaac design — and has gathered all the improvements into a single write-up, beginning with the Chaac v2.0 which combined the existing XBee-based communication system with an nRF52811 for Bluetooth connectivity.