Arduino homework2 - paino

paino.ino

#define BTN_MAX 12
#define BTN_MIN 4
#define BTN_NUM (BTN_MAX-BTN_MIN+1)
#define SPEAKER1 2
#define SPEAKER2 3

#define NOTE_F4  349
#define NOTE_G4  392
#define NOTE_A4  440
#define NOTE_B4  494
#define NOTE_C5  523
#define NOTE_D5  587
#define NOTE_E5  659
#define NOTE_F5  698
#define NOTE_G5  784

int pin[BTN_NUM] = {12, 11, 10, 9, 8, 7, 6, 5, 4};
int note[BTN_NUM] = {NOTE_F4, NOTE_G4, NOTE_A4, NOTE_B4, NOTE_C5, NOTE_D5, NOTE_E5, NOTE_F5, NOTE_G5};
int speaker[] = {SPEAKER1, SPEAKER2};
bool btnState[BTN_NUM];
bool playing[BTN_NUM];
int channel[2];

void setup()
{
    for(int i = 0; i < BTN_NUM; i++)
        pinMode(i, OUTPUT);
    for(int i = 0; i < 2; i++)
        pinMode(speaker[i], OUTPUT);
    Serial.begin(9600);
    for(int i = 0; i < 2; i++)
        channel[i] = -1;
}
void loop()
{
    // read btns
    for(int i = 0; i < BTN_NUM; i++)
    {
        btnState[i] = digitalRead(pin[i]);
    }

    for(int i = 0; i < BTN_NUM; i++)
    {
        if(btnState[i]) // on
        {
            for(int j = 0; j < 2; j++)
            {
                if(!playing[i] && channel[j] == -1)
                {
                    channel[j] = i;
                    playing[i] = true;
                    break;
                }
            }
        }
        else // off
        {
            for(int j = 0; j < 2; j++)
            {
                if(playing[i] && channel[j] == i)
                {
                    channel[j] = -1;
                    playing[i] = false;
                    break;
                }
            }
        }
    }

    for(int i = 0; i < 2; i++)
    {
        if(channel[i] != -1)
        {
            Serial.print("Play channel=");
            Serial.println(i);
            tone(speaker[i], note[channel[i]]);
            // delay(1);
            // noTone(speaker[i]);
        }
        else
            noTone(speaker[i]);
    }
    // dbg
    Serial.print(channel[0]);
    Serial.print(' ');
    Serial.println(channel[1]);
    // for(int i = 0; i < BTN_NUM; i++)
    // {
    //     Serial.print(btnState[i]);
    //     Serial.print(' ');
    // }
    Serial.print('\n');
    // delay(1);
}