This tutorial covers using both external pull down and pull up resistors with pushbuttons.

Then it also shows how to use arduino internal pullup resistors associated with every Arduino digital input pin.

Here is the link to the tutorial:

EXPANDED TECHNICAL DETAILS

Precision Digital Input Interfacing

This fundamental tutorial explores the critical role of resistors in ensuring stable, glitch-free digital inputs for all Arduino-based logic systems.

• The Floating Pin Problem: Explains why a digital pin without a resistor produces "Noise" and unpredictable behavior. It demonstrates how a Pull-up resistor ties the pin to 5V (default HIGH), while a Pull-down ties it to Ground (default LOW), ensuring a clean and reliable state change.
• Internal INPUT_PULLUP Mode: Showcases the Arduino's built-in feature to activate internal 20kΩ resistors. This allows developers to simplify their circuits by omitting physical resistors, requiring only the button and a connection to the Ground pin.

Practical Application

• Debounced Switch Logic: Includes a software framework for filtering out mechanical "Bouncing" that occurs when a physical switch is toggled, essential for accurate count-tracking or menu navigation.