In a circuit with a switch and a pull-down resistor, why does the high impedance of the input not discourage current from flowing into pin? - Arduino Stack Exchange
Arduino Uno Example Sketch: Digital Input Pullup - Arduino - Engineering and Component Solution Forum - TechForum │ Digi-Key
How to enable internal pull-up resistor of arduino uno | Arduino uno tutorial - YouTube
arduino uno - Do I need a pull-up/down resistor for button LED circuit? - Arduino Stack Exchange
Pull-up Resistor vs Pull-down - Differences, Arduino Guide - Latest Open Tech From Seeed
How to Wire a Button to Arduino? Using Internal Pull-Up. - Circuit Journal