Wiring

The following components are required to wire buttons to an input shift register:

  • A 74HC165 chip.
  • Buttons or switches.
  • 10kΩ resistors.
  • 0.1µF capacitors.

Important

MobiFlight only supports connecting buttons to input shift registers. Encoders must be connected directly to a board.

The 10kΩ resistors are required on every input pin, even if you aren’t attaching a button to that pin, to avoid false input events.

Schematic for wiring a single 74HC165 chip.

MobiFlight supports up to four 74HC165 chips connected in series. When wiring the chips it is important to wire them with the right most chip in the series one connected to the board’s data input line. The clock and latch pins are shared across all chips.

Schematic for wiring four 74HC165 chips in series.

(Buttons and pull-up resistors omitted for clarity)