Buttons and Touch Input

The micro:bit has two forward facing buttons either side of the display, buttonA and buttonB. These are intuitively exposed on the [MicroBit](../ubit.md) object as uBit.buttonA and uBit.buttonB. A third button, uBit.buttonAB is used to detect the combined input of buttonA and buttonB, and is an instance of the class [MicroBitMultiButton](multibutton.md).

Hardware buttons are notoriously renowned for generating multiple open/close transitions for what a user perceives as a single press, which can make depending on the raw input of a button unreliable. To combat this, a technique called ‘debouncing’ is used, which periodically polls the state of the button, when a transition from open to close (and vice versa) is detected. Through periodically polling the button, we get a more accurate representation of the state of a button.

MicroBitButton`s and [`MicroBitMultiButton](multibutton.md)s are debounced in software and provide a number of events that can be used to detect different variations of presses.

The MicroBitButton debouncing mechanism is used to provide resistive touch sensing on [MicroBitPin](io.md)s and could also be used on external ‘button-like’ input if required.