01·analogRead() and the potentiometer — reading voltage

Introduction

The first lesson on analog signals. The digital world knows only HIGH and LOW, but reality is analog — brightness, temperature, and knob position change smoothly. Arduino Uno/Nano has a built-in analog-to-digital converter (ADC) with 10-bit resolution that turns a 0–5V voltage into an integer from 0 to 1023. You will learn the analogRead() function, the A0–A5 analog pins, wire a potentiometer as a voltage divider, and watch the changing values in the Serial Monitor. This is the foundation for the rest of the chapter: map(), PWM, and the first light sensor.