connectix

A quiet weather station on a Raspberry Pi Zero

Temperature, humidity and pressure on the balcony, logged every minute, with no cloud account involved.

Hardware

A Pi Zero 2 W, a BME280 on I²C and a radiation shield made from stacked plant saucers. Without the shield, direct sun adds a good eight degrees to the reading.

sudo raspi-config nonint do_i2c 0
i2cdetect -y 1    # the BME280 shows up at 0x76 or 0x77

Software

A forty-line Python script reads the sensor and appends a line to a CSV file. A systemd timer runs it every minute. Once a night the file is compressed and copied to the NAS.

The sensor heats itself slightly when polled too often. Forced mode with one reading per minute keeps it within a tenth of a degree of a reference thermometer.

Things that went wrong

• The SD card died after eight months of writes. The log now lives in RAM and is flushed every hour.
• Long I²C wires do not work. The sensor sits on a short cable, the Pi sits inside.