Questions about wires

[sbridger]

Does BRAKE (purple wire) connect inside XH18?

(Could it be used for SWIM pin for programming/bootloader after initial modification?)

What pin of cpu drives white wire (Motor Enable) and what polarity is ON?

[hurzhurz]

Hi,

the purble/brake wire is a loose end inside the case and not connected anywhere...

The white wire can't be controlled separately. It is switched together with the power supply of the XH18.
And this is done by a transistor with something like a "soft power latch" circuit.
So power is first enabled as long as you press the power button and then held on by the cpu pin PD7:
https://github.com/hurzhurz/xh18lcd/blob/master/hardware.md#power-supply--control