An SMD momentary switch is placed under the trackball to give you a select switch. The BTN line will be pulled low when the switch is pressed.
Also included on the Trackballer are 4 LEDs: red, blue, green and white. These can be powered to light the clear trackball up any color you can imagine.
All features are broken out to a 0.1" pitch header. Regulated, 2.5-5.25VDC power must be provided to power the Hall sensors. The trackball is attached with strong CA glue. Board comes as shown, with all components populated.
The hall-effect sensors and trackball combo are surprisingly sensitive. A slight roll of the trackball creates multiple high/low transitions on the four axis pins, easily picked up by any microcontroller. A 360° rotation of the trackball, along a single axis, will result in about 9 high/low transitions.