/*
  matrix-scan a set of LEDs

  pins:

  "rows" 12 & 13 go to a 220Ω resistor, then to 2 LEDs each (positive
  / long stem side); also to a 10kΩ resistor then to 2
  phototransistors (collector / long stem side)

  also, from between the 10kΩ and the phototransistors, wire goes to
  A1 & A2

  "columns"
  14 & 15 go to 2 LEDs each (negative / short stem side)

  so that given one of 12|13 and one of 14|15, one LED is identified
 */

#include <driver/dac.h>

int currentLed = 0;
int lastSeen = -1;

#define DEBUG 0

const size_t row_count = 5;
const size_t col_count = 5;

const int rows[row_count] = { 5, 23, 19, 18, 26 };
const int cols[col_count] = { 17, 33, 16, 21, 22 };
const int adc[row_count] = { 2, 4, 12, 27, 14 };
const int ampEnable = 32;

const int octave_shift = 4;

void setup() {
  Serial.begin(115200);

  pinMode(ampEnable, OUTPUT);
  digitalWrite(ampEnable, LOW);

  dac_i2s_disable();
  dac_output_enable(DAC_CHANNEL_1);

  for (int i=0;i<row_count;++i) {
    pinMode(rows[i], OUTPUT|PULLUP);
    pinMode(adc[i], INPUT);
  }
  for (int i=0;i<col_count;++i) {
    pinMode(cols[i], OUTPUT|PULLDOWN);
  }

  currentLed = 0;
  lastSeen = -1;
}

void play(uint32_t freq) {
  dac_cw_config_t wave_config = {
  en_ch: DAC_CHANNEL_1,
  scale: DAC_CW_SCALE_2,
  phase: DAC_CW_PHASE_0,
  freq: octave_shift*freq,
  offset: 0,
  };

  dac_cw_generator_config(&wave_config);
  dac_cw_generator_enable();

  digitalWrite(ampEnable, HIGH);
}

void mute() {
  digitalWrite(ampEnable, LOW);
  dac_cw_generator_disable();
}

void tristate(int pin) {
  pinMode(pin,OUTPUT|PULLDOWN);
  digitalWrite(pin,LOW);
  pinMode(pin,INPUT);
}

void power(int pin) {
  pinMode(pin,OUTPUT|PULLUP);
  digitalWrite(pin,HIGH);
}

void ground(int pin) {
  pinMode(pin,OUTPUT|PULLDOWN);
  digitalWrite(pin,LOW);
}

void enableLed(int led) {
  int row = (led/col_count) % row_count ;
  int col = led%col_count;

#if DEBUG & 0x02
  Serial.print("enabling ");
  Serial.print(row);
  Serial.print(" ");
  Serial.println(col);
#endif

  for (int i=0;i<row_count;++i) {
    if (i==row) { power(rows[i]); }
    else { ground(rows[i]); }
  }
  for (int i=0;i<col_count;++i) {
    if (i==col) { ground(cols[i]); }
    else { tristate(cols[i]); }
  }
}

int sense(int led) {
  int row = (led/col_count)%row_count;

  int value = analogRead(adc[row]);

#if DEBUG & 0x04
  Serial.println(value);
#endif

  return value < 500;
}

uint32_t notes[] = {
                    261, // C4
                    277,
                    294, // D4
                    311,
                    330, // E4
                    349, // F4
                    370,
                    392, // G4
                    415,
                    440, // A4
                    466,
                    494, // B4

                    523, // C5
                    554,
                    587, // D5
                    622,
                    659, // E5
                    698, // F5
                    740,
                    783, // G5
                    831,
                    880, // A5
                    932,
                    988, // B5

                    1046, // C6
};

void loop() {
#if DEBUG & 0x01
  Serial.print("current led ");
  Serial.println(currentLed);
#endif

  enableLed(currentLed);
  delay(5);
  if (sense(currentLed)) {
    if (lastSeen != currentLed) {
      lastSeen = currentLed;
      Serial.print(currentLed);
      Serial.println(" proximity!");
      play(notes[currentLed]);
    }
  }
  else if (lastSeen == currentLed) {
    lastSeen = -1;
    mute();
  }

  currentLed = (currentLed+1)%(row_count*col_count);
}