ESP-12F + bme280 sensor. It measures humidity, temperature and pressure. It communicates using mqtt. When in standby it consumes < 1mA which allows it to work for more then 6 months on one set of batteries.
- ESP-12F - or compatible device
- BME280
- LT1129-3.3
- 2x 2xAA in series battery holders
- capacitors and resistors