Pull-Up Resistor
Fleeting- External reference: https://en.wikipedia.org/wiki/Pull-up_resistor
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pull-up resistor (PU) or pull-down resistor (PD) is a resistor used to ensure a known state for a signal.
pull-down resistor connected between the circuit and ground ensures a well-defined ground voltage (i.e. logical low) across the remainder of the circuit when the switch is open