The project is at a very early stage of development. You can see the status of this and other nodes from my work panel (In Spanish)
You can give your opinion in the forum while I design it, I receive the materials, and I assemble the test units.
If someone asks, the PCB has a hump because there was free space and I added a AVRISP+UART adapter.
It is a sensor powered by 2 AA batteries or 1 CR2032 battery, it integrates a temperature, humidity and light sensor. It also has two pins for a magnetic push-button in crystal housing and 3 expansion connectors.