Here’s the Arduino code for the keyboard project we did with Alex Katz at the Build Hack Make summer camp.
#include "notes.h"
const int BUTTON_PIN = 2;
const int SPEAKER_PIN = 11;
void setup() {
Serial.begin(9600);
// Initialize the speaker pin
pinMode(SPEAKER_PIN, OUTPUT);
// Initialize the button pin. Using the INPUT_PULLUP mode means that the baseline value is HIGH,
// and when the button is pressed the value is LOW. This mode allows us to skip adding pull up or
// pull down resistors externally.
pinMode(BUTTON_PIN, INPUT_PULLUP);
}
void loop() {
//Serial.println(digitalRead(BUTTON_PIN));
//delay(1000);
// Check whether the button is pressed. If the value is LOW it means the button is being pressed.
if (digitalRead(BUTTON_PIN) == LOW)
{
// Play a note on the speaker.
tone(SPEAKER_PIN, NOTE_C4);
}
else
{
// Stop playing the note on the speaker.
noTone(SPEAKER_PIN);
}
}#include "notes.h"
const int NUM_BUTTONS = 6;
const int BUTTON_NOTES[NUM_BUTTONS] = {NOTE_C4, NOTE_D4, NOTE_E4, NOTE_F4, NOTE_G4, NOTE_A4};
const int BUTTON_PINS[NUM_BUTTONS] = {2, 3, 4, 5, 6, 7};
const int SPEAKER_PIN = 11;
void setup() {
// Initialize the pin we're going to use for the speaker.
pinMode(SPEAKER_PIN, OUTPUT);
// Initialize each of the pins we're going to use for the buttons. Using the INPUT_PULLUP mode
// means that the baseline value is HIGH, and when the button is pressed the value is LOW. This
// mode allows us to skip adding pull up or pull down resistors externally.
for (int i = 0; i < NUM_BUTTONS; ++i) {
pinMode(BUTTON_PINS[i], INPUT_PULLUP);
}
}
void loop() {
// This variable tracks which button is being actively pressed down. It has a static lifetime,
// meaning its value persists across invocations of loop().
static int activeButtonIdx = -1;
// This variable tracks whether a button is currently being pressed, we use it to know whether
// we should reset activeButtonIdx.
bool buttonPressed = false;
// Iterate through the array of buttons. If we find a button that is being pressed, handle it
// accordingly. The way this is written gives precedence to the button with the lower index in
// the array. Meaning if buttons 0 and 1 are being pressed down simultaneously, we will play
// button 0's tone.
for (int i = 0; i < NUM_BUTTONS; ++i) {
// Check if this button is currently being pressed.
if (digitalRead(BUTTON_PINS[i]) == LOW) {
// Check if this is a new button press.
if (activeButtonIdx != i) {
// Stop currently playing tone (if there is one).
if (activeButtonIdx >= 0) {
noTone(SPEAKER_PIN);
}
// Play the new tone and set activeButtonIdx.
tone(SPEAKER_PIN, BUTTON_NOTES[i]);
activeButtonIdx = i;
}
// If we've detected a button being pressed, we want to bail out of the loop regardless of
// whether it is a new button press. This is what gives "priority" to buttons with lower
// indices.
buttonPressed = true;
break;
}
}
// If we haven't detected any of our buttons being actively pressed down, we should stop playing
// a tone and reset activeButtonIdx.
if (!buttonPressed && activeButtonIdx >= 0) {
noTone(SPEAKER_PIN);
activeButtonIdx = -1;
}
}Notes.h paste this into into a textedit file and add it to the Arduino sketch by going to sketch-> add file:
#define NOTE_B0 31
#define NOTE_C1 33
#define NOTE_CS1 35
#define NOTE_D1 37
#define NOTE_DS1 39
#define NOTE_E1 41
#define NOTE_F1 44
#define NOTE_FS1 46
#define NOTE_G1 49
#define NOTE_GS1 52
#define NOTE_A1 55
#define NOTE_AS1 58
#define NOTE_B1 62
#define NOTE_C2 65
#define NOTE_CS2 69
#define NOTE_D2 73
#define NOTE_DS2 78
#define NOTE_E2 82
#define NOTE_F2 87
#define NOTE_FS2 93
#define NOTE_G2 98
#define NOTE_GS2 104
#define NOTE_A2 110
#define NOTE_AS2 117
#define NOTE_B2 123
#define NOTE_C3 131
#define NOTE_CS3 139
#define NOTE_D3 147
#define NOTE_DS3 156
#define NOTE_E3 165
#define NOTE_F3 175
#define NOTE_FS3 185
#define NOTE_G3 196
#define NOTE_GS3 208
#define NOTE_A3 220
#define NOTE_AS3 233
#define NOTE_B3 247
#define NOTE_C4 262
#define NOTE_CS4 277
#define NOTE_D4 294
#define NOTE_DS4 311
#define NOTE_E4 330
#define NOTE_F4 349
#define NOTE_FS4 370
#define NOTE_G4 392
#define NOTE_GS4 415
#define NOTE_A4 440
#define NOTE_AS4 466
#define NOTE_B4 494
#define NOTE_C5 523
#define NOTE_CS5 554
#define NOTE_D5 587
#define NOTE_DS5 622
#define NOTE_E5 659
#define NOTE_F5 698
#define NOTE_FS5 740
#define NOTE_G5 784
#define NOTE_GS5 831
#define NOTE_A5 880
#define NOTE_AS5 932
#define NOTE_B5 988
#define NOTE_C6 1047
#define NOTE_CS6 1109
#define NOTE_D6 1175
#define NOTE_DS6 1245
#define NOTE_E6 1319
#define NOTE_F6 1397
#define NOTE_FS6 1480
#define NOTE_G6 1568
#define NOTE_GS6 1661
#define NOTE_A6 1760
#define NOTE_AS6 1865
#define NOTE_B6 1976
#define NOTE_C7 2093
#define NOTE_CS7 2217
#define NOTE_D7 2349
#define NOTE_DS7 2489
#define NOTE_E7 2637
#define NOTE_F7 2794
#define NOTE_FS7 2960
#define NOTE_G7 3136
#define NOTE_GS7 3322
#define NOTE_A7 3520
#define NOTE_AS7 3729
#define NOTE_B7 3951
#define NOTE_C8 4186
#define NOTE_CS8 4435
#define NOTE_D8 4699
#define NOTE_DS8 4978