Very interesting. Coincidentally, a user recently contacted me about extending the capability of OpenSprinkler, such as support for 1-wire devices, and in the middle of thinking about this, I decided to make an extension module which make use of the existing zone expander connector to hook up various I2C devices. Because OpenSprinkler 3.0 zone expander uses I2C, the connector has all the necessary pins. So I am thinking of making a variant of the zone expander called 1-Wire / Analog extension module, which plugs into the zone expander connector, and it will serve as a 1-wire device master, and also will have ADS1015 / 1115 to provide analog reading capability. The nice thing about this is that just like the zone expander, it will have a incoming 2×5 connector and outgoing 2×5 connector, so existing zone expanders can still be plugged into this module. So some part of this plan happen to coincide with your idea!