// https://forum.arduino.cc/t/using-nano-to-activated-up-to-8-songs-on-a-dyhv20t-after-using-a-micro-switch/1406508/38

// File: nano_dyhv20t_button_player.ino

#include <SoftwareSerial.h>
#define RX_PIN 10          // Arduino RX (connect to DY-HV20T TX)
#define TX_PIN 11          // Arduino TX (connect to DY-HV20T RX)
#define BUTTON_PIN 2       // Button input pin
SoftwareSerial audioSerial(RX_PIN, TX_PIN);
const int totalTracks = 8;
int currentTrack = 1;
bool lastButtonState = HIGH;
unsigned long lastDebounceTime = 0;
const unsigned long debounceDelay = 50;

void setup() {
  Serial.begin(9600);
  audioSerial.begin(9600);
  pinMode(BUTTON_PIN, INPUT_PULLUP);
  // delay(2000);
  setVolume(20); // Medium volume
  Serial.println("System ready. Waiting for button press...");
}

void loop() {
  bool buttonState = !digitalRead(BUTTON_PIN); // Invert reading for NC button
  if (buttonState != lastButtonState) {
    lastDebounceTime = millis();
    lastButtonState = buttonState;
  }
  if ((millis() - lastDebounceTime) > debounceDelay && buttonState == HIGH) {
    playTrack(currentTrack);
    currentTrack++;
    if (currentTrack > totalTracks) {
      currentTrack = 1;
    }
    while (!digitalRead(BUTTON_PIN)); // Wait for release
    // delay(100);
  }
}

void playTrack(int trackNumber) {
  Serial.print("Playing track number: ");
  Serial.println(trackNumber);
  audioSerial.write((uint8_t)0xAA);             // start byte
  audioSerial.write((uint8_t)0x07);             // play command
  audioSerial.write((uint8_t)0x02);
  audioSerial.write((uint8_t)0x00);
  audioSerial.write((uint8_t)trackNumber);
  audioSerial.write((uint8_t)((0xAA + 0x07 + 0x02 + 0x00 + trackNumber) & 0xFF));
  // delay(1000);  // wait after sending command
}

void setVolume(uint8_t volume) {
  Serial.print("Setting volume to: ");
  Serial.println(volume);
  audioSerial.print("VOL ");
  audioSerial.print(volume);
  audioSerial.print("\r\n");
}