Hi there,
I have managed to get my Spark running 0.27 with the PI running develop branch. But for the life on me, can’t seem to get the spark to see my one-wire sensors ? I have red to 5v, Yellow to one-wire and Black to Gnd. Are there any debug tools I can use at all to point me in the right direction ? I have put a meter on the wires Both yellow and red show 5v with black as GND.
Are you sure your wiring is correct?
In the past I had sensors that used red for data. I kid you not. I was angry at my supplier.
Have just tried swapping the red / yellow over but still nothing ? Apart from the UI device configuration is there anywhere else to look ?
I have just checked and I ordered DS18B20 are these the right ones ? Scratching my head now 
They should show up on the touch screen automatically. Please see this image:
I test all devices before they ship that they are detected OneWire sensors.
I have ordered some from your store as wanted the threaded sensors as well for the final HERMS setup. I have just tested with two other ones I had lying around and they work, so very bizarre. But will now be able to run a water test tonight finally !
You can find ground with a multimeter but you need to set it to check resistance. Take 2 wires and attach leads to them if you don’t get a reading swap the red/black leads from the meter once you get a resistance reading looks t your multimeter the lead that goes to common is ground. The other 2 are either 5v or data but once you establish ground the rest is 50/50