What are the ports on the back of Twine?
Twine has three holes on the back. What are they for?
3.5mm port - this is for external sensors. While you can technically use 4-conductor audio cables in this, we've designed custom shielded cables that keep the sensor signal from degrading over distances.
micro USB port - this is for external power, not data. You can power Twine off of your computer or any cellphone charger. While your Twine is on external power, it won't use the batteries (and it won't charge them). If you unplug Twine from external power and it has good batteries in it, Twine won't miss a beat.
LED - you need to see the status light somehow! What is the light trying to tell me?