Please refer to this GitHub Repository for the code for all Arduinos.

Repository Sections

master-arduino

We are currently supplying power to the Arduinos via USB. If we used DC converters from the batteries to the Arduinos, we might save some electricity.

Real Time Clock Setup for SD3231

Tutorial on arduino.com

Data logging on SD-card

this randomnerdtutorial.com leads you through SD-card usage with an arduino.

Wireless communication with NRF24L01

We have long-run antennas for wireless communication (NRF24L01 Tutorial).
You should solder a 10uf electrolytic capacitor between the power leads.

How to connect several SPI devices to Arduino.