NRF24 Weather Station

The station works with up to 4 battery-powered transmitters, each with a DS18B20 temperature sensor.

The receiver displays:

current date, time of sunrise, time of sunset, Moon phase
temperature, humidity, pressure from the receiver's BME280 sensor
temperatures from the transmitters
battery voltage of each of the transmitters
time since last reading from each of the transmitters

There is an adjustable freezing alarm (it turns on when at least one of the transmitter reading falls below the set temperature).

All the readings can be logged to a SD card.

Hardware used

Transmitter

Arduino Pro Mini (3.3V/8MHz)
NRF24L01+
DS18B20 sensor
3xAA battery holder

Receiver

Arduino UNO with power supply
NRF24L01+
BME280 sensor
DS3231 AT24C32 Real Time Clock
PCF8574 I2C expansion board
LCD2004 with turning knob and SD card reader (Ramps1.4 compatible display)