Mission 10 · Stage 1

Mini Light Show

timed show sequences

Run a timed light show sequence on a bar graph.

Pin connections

Part 1		Part 2
Arduino pin 2	→	LED bar graph A1
Arduino pin 3	→	LED bar graph A2
Arduino pin 4	→	LED bar graph A3
Arduino pin 5	→	LED bar graph A4
Arduino pin 6	→	LED bar graph A5
Arduino pin 7	→	LED bar graph A6
Arduino pin 8	→	LED bar graph A7
Arduino pin 9	→	LED bar graph A8
Arduino pin 10	→	LED bar graph A9
Arduino pin 11	→	LED bar graph A10
LED bar graph C10	→	Arduino GND

See it

Your own light show sequence!

Wave in, wave out, then blink all — a timed multi-step show.

Stage lights and signs run scripted sequences like this.

The story

The problem

One pattern is not enough — chain several timed acts together.

Think of it like

Like a dance routine: step one, step two, finale.

Meet the parts

Runs your sketch

Arduino

Brain

Loading part…

Ten segments you can light up

LED bar graph

Display

Loading part…

How it works

Act 1 — wave in

One segment at a time turns on from left to right — the bar fills up.

digitalWrite(FIRST_PIN + i, HIGH);
delay(80);

Hold full bar

Every segment stays on briefly before the next act.

delay(500);

Act 2 — wave out

Segments turn off one by one from right to left.

digitalWrite(FIRST_PIN + i, LOW);
delay(80);

Act 3 — blink together

The whole bar flashes three times — a finale before the pause.

allOn(); delay(150); allOff(); delay(150);

Reset and repeat

A long pause, then loop() runs the whole show from Act 1 again.

delay(800);

Then loop back to step 1

Build the circuit

Follow these steps in order. Match the wires to the colors shown.

1
Place Arduino
Place the Arduino (uno) on the breadboard.
Arduino placed!
Loading part…
2
Place LED bar graph
Place the LED bar graph (bar1) on the breadboard.
Loading part…
3
Connect Arduino pin 2 to LED bar graph (bar1) A1
Connect Arduino pin 2 to LED bar graph (bar1) A1.
4
Connect Arduino pin 3 to LED bar graph (bar1) A2
Connect Arduino pin 3 to LED bar graph (bar1) A2.
5
Connect Arduino pin 4 to LED bar graph (bar1) A3
Connect Arduino pin 4 to LED bar graph (bar1) A3.
6
Connect Arduino pin 5 to LED bar graph (bar1) A4
Connect Arduino pin 5 to LED bar graph (bar1) A4.
7
Connect Arduino pin 6 to LED bar graph (bar1) A5
Connect Arduino pin 6 to LED bar graph (bar1) A5.
8
Connect Arduino pin 7 to LED bar graph (bar1) A6
Connect Arduino pin 7 to LED bar graph (bar1) A6.
9
Connect Arduino pin 8 to LED bar graph (bar1) A7
Connect Arduino pin 8 to LED bar graph (bar1) A7.
10
Connect Arduino pin 9 to LED bar graph (bar1) A8
Connect Arduino pin 9 to LED bar graph (bar1) A8.
11
Connect Arduino pin 10 to LED bar graph (bar1) A9
Connect Arduino pin 10 to LED bar graph (bar1) A9.
12
Connect Arduino pin 11 to LED bar graph (bar1) A10
Connect Arduino pin 11 to LED bar graph (bar1) A10.
13
Connect LED bar graph (bar1) C10 to Arduino GND
Connect LED bar graph (bar1) C10 to Arduino GND.

Try it

Run the full show: fill up, hold, empty, blink, pause.
Try to predict which act comes next!

Peek at code

Helper functions

void allOff() {
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(FIRST_PIN + i, LOW);
  }
}
void allOn() {
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(FIRST_PIN + i, HIGH);
  }
}

allOff() and allOn() use loops so we do not write ten digitalWrite lines by hand.

Setup the bar

void setup() {
  for (int i = 0; i < NUM_LEDS; i++) {
    pinMode(FIRST_PIN + i, OUTPUT);
  }
}

Every bar pin is set to OUTPUT once in setup().

Full show sequence

void loop() {
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(FIRST_PIN + i, HIGH);
    delay(80);
  }
  delay(500);
  for (int i = NUM_LEDS - 1; i >= 0; i--) {
    digitalWrite(FIRST_PIN + i, LOW);
    delay(80);
  }
  delay(300);
  for (int n = 0; n < 3; n++) {
    allOn();
    delay(150);
    allOff();
    delay(150);
  }
  delay(800);
}

loop() chains wave-in, pause, wave-out, blink finale, and rest — a timed light show.

Show full sketch (mini-light-show.ino)

const int FIRST_PIN = 2;
const int NUM_LEDS = 10;
void allOff() {
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(FIRST_PIN + i, LOW);
  }
}
void allOn() {
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(FIRST_PIN + i, HIGH);
  }
}
void setup() {
  for (int i = 0; i < NUM_LEDS; i++) {
    pinMode(FIRST_PIN + i, OUTPUT);
  }
}
void loop() {
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(FIRST_PIN + i, HIGH);
    delay(80);
  }
  delay(500);
  for (int i = NUM_LEDS - 1; i >= 0; i--) {
    digitalWrite(FIRST_PIN + i, LOW);
    delay(80);
  }
  delay(300);
  for (int n = 0; n < 3; n++) {
    allOn();
    delay(150);
    allOff();
    delay(150);
  }
  delay(800);
}

Quick quiz

Q1. Where does repeating work belong?

A. loop() ✓
B. setup()
C. pinMode only

Why: Correct—loop() runs again and again.

Q2. What makes this a "show sequence"?

A. Several timed steps in order in loop() ✓
B. One delay() only
C. No digitalWrite() calls

Why: Correct — ordered steps with delays build the full show.

Code lab — try on your own

Speed up the wave — change delay(80) to delay(40) in both wave loops.
Hint: Lines inside the for-loops that light segments one by one.
Add one extra flash — change the blink loop from n < 3 to n < 4.
Hint: Find for (int n = 0; n < 3; n++).

Code walkthrough

A line-by-line tour of the sketch — the same steps as in Robo Gurukul Studio.

Program overview

Technical

Sketches have globals, then setup() once, then loop() forever.

In this project

Run a timed light show sequence on a bar graph.

Why here

Read from top to bottom. Hover words or lines for help!

const int FIRST_PIN = 2;
const int NUM_LEDS = 10;
void allOff() {
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(FIRST_PIN + i, LOW);
  }
}
void allOn() {
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(FIRST_PIN + i, HIGH);
  }
}

setup()

Technical

Runs one time when the board turns on.

In this project

Sets up pins and libraries for Mini Light Show.

Why here

One-time setup belongs here—not in loop().

void setup() {
  for (int i = 0; i < NUM_LEDS; i++) {
    pinMode(FIRST_PIN + i, OUTPUT);
  }
}

loop()

Technical

Runs again and again after setup() is done.

In this project

This is the main action you see in Mini Light Show.

Why here

Repeating work (blink, read sensors) goes here.

void loop() {
  for (int i = 0; i < NUM_LEDS; i++) {
    digitalWrite(FIRST_PIN + i, HIGH);
    delay(80);
  }
  delay(500);
  for (int i = NUM_LEDS - 1; i >= 0; i--) {
    digitalWrite(FIRST_PIN + i, LOW);
    delay(80);
  }
  delay(300);
  for (int n = 0; n < 3; n++) {
    allOn();
    delay(150);
    allOff();
    delay(150);
  }
  delay(800);
}

Try this: Change numbers in loop(), then compile and run the simulator.

pinMode

Technical

Tells a pin if it listens or drives something.

In this project

Gets the Mini Light Show circuit ready in the simulator.

Why here

Goes in setup() because we only set pins once at the start.

    pinMode(FIRST_PIN + i, OUTPUT);

digitalWrite

Technical

Turns a pin ON or OFF.

In this project

Controls lights, motors, or buzzers in Mini Light Show.

Why here

Goes in loop() so it can keep changing while the program runs.

    digitalWrite(FIRST_PIN + i, LOW);

delay

Technical

Waits for some time. Nothing else runs during the wait.

In this project

Controls speed so you can see Mini Light Show in the simulator.

Why here

Right after an action that should stay the same for a moment.

    delay(80);

← 9. Electronic Candle 11. Push Button LED →