sketch-patterns

name	sketch-patterns
description	Canonical Arduino sketch templates for Uno Q — scaffold, breathing/fading LED (analogWrite for-loops), blink, button with INPUT_PULLUP, potentiometer analogRead, Servo sweep. Read this before writing any .ino sketch.

Arduino Sketch Patterns (Uno Q)

A small library of canonical, compilable templates. Read the matching reference file before writing a sketch — do not invent variants when a template exists.

The scaffold (every sketch)

void setup() {
    // pinMode calls go here
}

void loop() {
    // repeating logic goes here
}

No statements at global scope except #include, const, and #define. An empty setup() is incomplete — every pin used with digitalWrite, analogWrite, or analogRead needs a matching pinMode() in setup().

When to load each reference

Student asks for…	Read
Fade, breathe, smooth on/off	references/breathing.md
Blink, flash, on/off at 1 Hz	references/blink.md
Button, switch, pressed	references/button.md
Potentiometer, dial, knob, Serial value	references/potentiometer.md
Servo, sweep, angle	references/servo.md

Anti-pattern reminders (covered in detail in references)

• Breathing/fading LED uses analogWrite in ascending then descending for-loops. A boolean toggle between 0 and 255 is a blink, not a fade — never confuse the two.
• Blink uses digitalWrite with two delay(1000) calls. One delay leaves the LED in an indeterminate state on the next loop iteration.
• Button reads with INPUT_PULLUP and tests for LOW (pressed pulls the line down). Floating inputs read noise.
• Always Serial.begin(9600) in setup() before any Serial.print / Serial.println. Otherwise the Serial Monitor sees nothing.