Error for negative temperature

[ebaauw]

HomeKit apps display Error for temperature sensors when temperature drops below zero.

By default, HomeKit limits the Current Temperature characteristic to values between 0.0˚C and 100.0˚C. While this might be appropriate for room temperature, it is not for outside temperature.

Rather than spending money on a weather station, I run a little shell script that updates a CLIPTemperature and a CLIPHumidity sensor every 30 minutes from wunderground.com. When the temperature drops below zero, homebridge-hue sets the Current Temperature sensor to a negative value, which HomeKit doesn't accept as it's out of range, hence the Error.

Fix is easy: overwrite the default properties for the Current Temperature characteristic to allow a larger range. As this is a read-only characteristic, better set the range as large as conceivable: from absolute zero (-273.15, or rounded -273.2˚C) to 1000.0˚C. Even the iOS 10 Home app seems to like this. I suppose that's how accessories like the Eve Weather deal with this as well.

[ebaauw]

Fixed in v0.1.2.