How to use your Twine breakout board
Short version:
The easiest way to use the Twine breakout board is to hook up a set of contacts (switch, button, wire) between the IN and GND terminals (Fig 1). When the contacts are touching, the breakout is “closed”. When they aren’t, it’s “open”.
Longer version (for nerds):
The breakout has three terminals: “3.3V”, “IN”, and “GND”.
3.3V — power supply from the Twine. This voltage on this line will vary between 2.3 and 3.3V depending how the Twine is powered. When running on external power, this will stay constant at 3.3V. When running on batteries, this voltage will vary between 2.4-3.0V. The voltage will always be boosted to 3.0V just before the input is sampled. An internal power circuit limits current on this line to 50mA. Remember that any power drawn from this line will directly affect battery life.
IN — input to the Twine. This line is pulled to the Twine’s internal power rail by a 4.7K resistor. It is highly recommended to only pull this line low, and never drive it high. A great way to do this is to use an NPN transistor (Fig 3) or relay (Fig 4). Under no circumstances should you connect more than 3.3V to this port.
GND — connected directly to the Twine ground bus.
