Skylapse 0.5.4 — dew heater setup without a terminal

Dew heater support, for the optional hardware: a BME280 temperature and humidity sensor, and a heater on a GPIO pin that keeps the glass a couple of degrees above the dewpoint.

The sensor sits on the I²C bus, which Raspberry Pi OS ships switched off — turning it on is a boot-config change, which on a camera with no terminal was a dead end. There is a button for it now.

The card tells the four states apart rather than just failing: the feature is off, the bus is off, the bus is on but nothing is answering, or it is running and showing you the glass temperature, the dewpoint and the margin between them.