Hi, found this info I had sent my tech when we started using the HW3 Mini models. Hope it help, I believe I got it from the manual. May be other input/output options with the newer firmware. Can be confusing since when cutting the transformer cable white is the negative power and black and red can be tied together for the positive.
The GPIO connection has three inputs. Two are for the + and – power inputs and the third is a + ignition/key on input for installation in automotive applications.
We really only need to connect the + and – power connection but when the transformer wire is cut it includes the third ignition wire so is easiest to just go ahead and also connect to + power supply.
Below is a diagram of the GPIO connections when used in an automotive application. The wire colors correspond with an option cable we don’t use.
