Lesson 9 of 16

Build a piano

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const int BUZZER = 10; const int KEYS[] = {2, 3, 4, 5, 6, 7, 8, 9}; const int NOTES[] = {262, 294, 330, 349, 392, 440, 494, 523}; // C4-C5 const char* NAMES[] = {"Do", "Re", "Mi", "Fa", "Sol", "La", "Si", "Do"}; int playing = -1; // which key is sounding; −1 means none void setup() { Serial.begin(9600); for (int i = 0; i < 8; i++) { pinMode(KEYS[i], INPUT_PULLUP); // the 328P's own pull-up: no resistor needed } } void loop() { int pressed = -1; for (int i = 0; i < 8; i++) { if (digitalRead(KEYS[i]) == LOW) pressed = i; // with a pull-up, pressed reads LOW } if (pressed != playing) { playing = pressed; if (playing >= 0) { tone(BUZZER, NOTES[playing]); Serial.println(NAMES[playing]); } else { noTone(BUZZER); } } }

Stopped · Your code isn't running yet. Until you press Run, the board runs the program already on it.

Nothing printed yet. Press Run.

Eight buttons on D2-D9, one buzzer on D10. The internal pull-ups save eight resistors, and the sketch plays whichever key is down.

Play it from the figure
Pull-ups turn the logic upside down
Why only one note sounds at once

Pin	Connects to	What it does
`D2-D9`	One side of each key	Pulled up inside the chip; a press pulls the pin to GND.
`D10`	The buzzer's + leg	Plays the note with tone().
`GND`	The other side of every key, and the buzzer	The ground rail along the top of the breadboard.

Wire it in

Sensors and actuators this board drives, with the real connections.

All 16 parts on the Arduino Uno R3 page

Build a piano

Try it yourself

Serial monitor

Checks

Break it

Inputs

Parameters

Wire it in

Build a piano

Try it yourself

Serial monitor

Checks

Break it

Inputs

Parameters

Wire it in