Offline Choice Communicator

#include <Arduino.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include <Adafruit_PN532.h>
#include <DFRobotDFPlayerMini.h>
#include <Preferences.h>


// Hoisted type definitions
struct Choice {
  const char *uid;
  const char *category;
  const char *label;
  uint8_t audioTrack;
  const char *key;
};


// Forward declarations
bool stableButtonPressed(uint8_t pin);
String uidToString(const uint8_t *uid, uint8_t uidLength);
void drawMessage(const String &top, const String &bottom, const String &hint);
void showWelcome();
void playCurrentChoice();
void showCurrentChoice();
void confirmCurrentChoice();
void scanForTile();

constexpr uint8_t I2C_SDA_PIN = 21;
constexpr uint8_t I2C_SCL_PIN = 22;
constexpr uint8_t DFPLAYER_RX_PIN = 16; // ESP32 receives from DFPlayer TX
constexpr uint8_t DFPLAYER_TX_PIN = 17; // ESP32 sends through 1 kOhm resistor to DFPlayer RX
constexpr uint8_t CONFIRM_BUTTON_PIN = 32;
constexpr uint8_t REPEAT_BUTTON_PIN = 33;
constexpr int OLED_WIDTH = 128;
constexpr int OLED_HEIGHT = 64;
constexpr uint32_t BUTTON_DEBOUNCE_MS = 40;
constexpr uint32_t TAG_CLEAR_MS = 900;

Adafruit_SSD1306 display(OLED_WIDTH, OLED_HEIGHT, &Wire, -1);
Adafruit_PN532 nfc(I2C_SDA_PIN, I2C_SCL_PIN);
HardwareSerial dfSerial(2);
DFRobotDFPlayerMini player;
Preferences preferences;



// Replace the UID text below with the UID printed in the serial log for each tile.
// Keep audio tracks on the DFPlayer microSD as /mp3/0001.mp3 through /mp3/0005.mp3.
const Choice choices[] = {
  {"04A1B2C3D4E5", "Food", "Snack", 1, "food"},
  {"04B1C2D3E4F5", "Activity", "Music", 2, "activity"},
  {"04C1D2E3F4A5", "Clothing", "Jacket", 3, "clothing"},
  {"04D1E2F3A4B5", "Feeling", "Calm", 4, "feeling"},
  {"04E1F2A3B4C5", "Place", "Outside", 5, "place"}
};
constexpr size_t CHOICE_COUNT = sizeof(choices) / sizeof(choices[0]);

const Choice *currentChoice = nullptr;
String lastSeenUid;
uint32_t lastTagSeenAt = 0;
bool audioReady = false;
bool nfcReady = false;

bool stableButtonPressed(uint8_t pin) {
  if (digitalRead(pin) != LOW) return false;
  delay(BUTTON_DEBOUNCE_MS);
  if (digitalRead(pin) != LOW) return false;
  while (digitalRead(pin) == LOW) delay(5);
  return true;
}

String uidToString(const uint8_t *uid, uint8_t uidLength) {
  String result;
  for (uint8_t i = 0; i < uidLength; ++i) {
    if (uid[i] < 0x10) result += '0';
    result += String(uid[i], HEX);
  }
  result.toUpperCase();
  return result;
}

const Choice *findChoice(const String &uid) {
  for (size_t i = 0; i < CHOICE_COUNT; ++i) {
    if (uid.equalsIgnoreCase(choices[i].uid)) return &choices[i];
  }
  return nullptr;
}

void drawMessage(const String &top, const String &bottom, const String &hint) {
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println(top);
  display.setTextSize(2);
  display.setCursor(0, 16);
  display.println(bottom);
  display.setTextSize(1);
  display.setCursor(0, 48);
  display.println(hint);
  display.display();
}

void showWelcome() {
  drawMessage("Choice board", "Ready", "Place a picture tile here");
}

void playCurrentChoice() {
  if (currentChoice != nullptr && audioReady) {
    player.playMp3Folder(currentChoice->audioTrack);
  }
}

void showCurrentChoice() {
  if (currentChoice == nullptr) return;
  drawMessage(currentChoice->category, currentChoice->label, "Confirm or press Repeat");
  playCurrentChoice();
}

void confirmCurrentChoice() {
  if (currentChoice == nullptr) {
    drawMessage("No tile selected", "", "Place a picture tile here");
    return;
  }
  uint32_t count = preferences.getUInt(currentChoice->key, 0) + 1;
  preferences.putUInt(currentChoice->key, count);
  String message = String("Saved: ") + String(count) + " times";
  drawMessage(currentChoice->category, currentChoice->label, message);
  playCurrentChoice();
}

void scanForTile() {
  if (!nfcReady) return;
  uint8_t uid[7];
  uint8_t uidLength = 0;
  if (!nfc.readPassiveTargetID(PN532_MIFARE_ISO14443A, uid, &uidLength, 40)) {
    if (lastSeenUid.length() > 0 && millis() - lastTagSeenAt > TAG_CLEAR_MS) {
      lastSeenUid = "";
    }
    return;
  }

  String uidText = uidToString(uid, uidLength);
  lastTagSeenAt = millis();
  if (uidText == lastSeenUid) return;
  lastSeenUid = uidText;

  currentChoice = findChoice(uidText);
  Serial.print("NFC tile UID: ");
  Serial.println(uidText);
  if (currentChoice == nullptr) {
    drawMessage("New picture tile", "Not set up", "Copy its UID from serial log");
    return;
  }
  showCurrentChoice();
}

void setup() {
  Serial.begin(115200);
  pinMode(CONFIRM_BUTTON_PIN, INPUT_PULLUP);
  pinMode(REPEAT_BUTTON_PIN, INPUT_PULLUP);
  preferences.begin("choiceboard", false);

  Wire.begin(I2C_SDA_PIN, I2C_SCL_PIN);
  if (!display.begin(SSD1306_SWITCHCAPVCC, 0x3C)) {
    Serial.println("OLED not found at 0x3C");
  } else {
    display.dim(true);
    showWelcome();
  }

  nfc.begin();
  uint32_t version = nfc.getFirmwareVersion();
  if (version != 0) {
    nfc.SAMConfig();
    nfcReady = true;
  } else {
    drawMessage("Reader needs check", "NFC offline", "Check 3V3, SDA, and SCL");
  }

  dfSerial.begin(9600, SERIAL_8N1, DFPLAYER_RX_PIN, DFPLAYER_TX_PIN);
  audioReady = player.begin(dfSerial, true, true);
  if (audioReady) {
    player.volume(16); // deliberately moderate volume: range is 0 to 30
  } else {
    Serial.println("DFPlayer not found; visual choice board still works.");
  }
}

void loop() {
  scanForTile();
  if (stableButtonPressed(CONFIRM_BUTTON_PIN)) confirmCurrentChoice();
  if (stableButtonPressed(REPEAT_BUTTON_PIN) && currentChoice != nullptr) showCurrentChoice();
}