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

Let's put on a light show!

Lights fill up, empty out, then flash all together — your own mini light show!

Stage lights and big signs play timed shows just like this!

The story

The problem

One pattern is fun, but a real show puts several fun parts together in order.

Think of it like

It's like a little dance routine — step one, step two, then a big finish!

Meet the parts

It thinks and runs the whole light show.

Arduino

The brain

Loading part…

Ten little lights in a line that put on the show.

LED bar graph

The row of lights

Loading part…

How it works

Part 1 — fill up

The lights turn on one by one, from left to right, until the whole row is glowing.

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

Hold the full row

All the lights stay on together for a moment before the next part.

delay(500);

Part 2 — empty out

Now the lights turn off one by one, from right to left, until the row is dark.

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

Part 3 — flash together

All the lights flash on and off three times — that is the big finish!

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

Rest, then do it again

A nice long rest, then loop() jumps back and plays the whole show 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 — ready to build!
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

Press the green Run button — watch the full show: fill up, hold, empty, flash, rest.
Try to guess which part comes next!

Peek at code

The all-on and all-off helpers

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 to switch all ten lights at once, so we don't write ten lines by hand.

Get all the lights ready

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

setup() gets every light pin ready, one after another, so they can all glow.

The whole show

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() plays the show in order: fill up, hold, empty out, flash three times, then rest.

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. Which part runs again and again?

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

Why: Yes! loop() runs again and again, forever.

Q2. What makes this a light show?

A. Several timed parts that play in order ✓
B. Just one wait
C. No lights at all

Why: Yes! Putting fun parts in order with waits makes the whole show.

Code lab — try on your own

Speed up the wave — change delay(80) to delay(40) in both wave parts.
Hint: These are the delay lines inside the loops that light the lights one by one.
Add one more flash — change the flash count 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 Robot Gurukul Studio.

Program overview

Big idea

Every Arduino program has a top part, a setup() part that runs once, and a loop() part that runs again and again.

In this project

A row of ten lights fills up, empties out, and flashes — a real light show!

Tip

Read from the top to the bottom. Tap any word or line if you need 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()

Big idea

setup() runs one time when the board turns on.

In this project

It gets all ten light pins (starting at pin 2) ready.

Why here

Things we do only once go inside setup().

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

loop()

Big idea

loop() runs again and again, forever.

In this project

This is where the whole light show plays from start to finish.

Why here

Things that repeat go inside loop().

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 a delay number inside loop(), then press Run to make the show faster or slower.

pinMode

Big idea

pinMode tells a pin if it will listen or push power out.

In this project

It makes each light pin ready to push power to a light.

Why here

It goes in setup() because we only set it once.

    pinMode(FIRST_PIN + i, OUTPUT);

digitalWrite

Big idea

digitalWrite turns a pin ON or OFF.

In this project

ON lights up a light, OFF turns it dark. Here it turns one light off.

Why here

It goes in loop() so the lights can keep changing.

    digitalWrite(FIRST_PIN + i, LOW);

delay

Big idea

delay means wait. Nothing else happens while it waits.

In this project

It sets how fast each part of the show plays.

Why here

Right after a light turns on or off.

    delay(80);

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