Voice-Interactive Desk Buddy

#include <Arduino.h>
#include <SPI.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>

void drawScreen();
String hexByte(uint8_t value);
void showVoicePacket();

constexpr int VC02_RX_PIN = 16;
constexpr int VC02_TX_PIN = 17;
constexpr int TOUCH_PIN = 27;
constexpr int OLED_SCK_PIN = 18;
constexpr int OLED_MOSI_PIN = 23;
constexpr int OLED_RESET_PIN = 25;
constexpr int OLED_DC_PIN = 26;
constexpr int OLED_CS_PIN = 32;
constexpr unsigned long TOUCH_DEBOUNCE_MS = 40;
constexpr unsigned long MESSAGE_HOLD_MS = 3500;

Adafruit_SSD1306 display(128, 64, &SPI, OLED_DC_PIN, OLED_RESET_PIN, OLED_CS_PIN);
HardwareSerial voiceSerial(2);

bool lastTouchReading = false;
bool touchState = false;
unsigned long touchChangedAt = 0;
unsigned long messageShownAt = 0;
String statusLine = "Ready";
String packetLine = "Touch to wake";

void drawScreen() {
  display.clearDisplay();
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);
  display.setCursor(0, 0);
  display.println(F("AI DESK BUDDY"));
  display.drawFastHLine(0, 11, 128, SSD1306_WHITE);
  display.setCursor(0, 18);
  display.print(F("Status: "));
  display.println(statusLine);
  display.setCursor(0, 34);
  display.println(F("Voice command:"));
  display.setCursor(0, 47);
  display.println(packetLine);
  display.display();
}

String hexByte(uint8_t value) {
  const char hex[] = "0123456789ABCDEF";
  String text;
  text += hex[(value >> 4) & 0x0F];
  text += hex[value & 0x0F];
  return text;
}

void showVoicePacket() {
  String bytes;
  unsigned long lastByteAt = millis();
  while (millis() - lastByteAt < 35) {
    while (voiceSerial.available()) {
      uint8_t value = static_cast<uint8_t>(voiceSerial.read());
      if (bytes.length() > 0) bytes += ' ';
      bytes += hexByte(value);
      lastByteAt = millis();
    }
    delay(1);
  }

  if (bytes.length() > 0) {
    statusLine = "Command received";
    packetLine = bytes.substring(0, 20);
    messageShownAt = millis();
    drawScreen();
    Serial.print(F("VC-02 packet: "));
    Serial.println(bytes);
  }
}

void setup() {
  Serial.begin(115200);
  pinMode(TOUCH_PIN, INPUT);
  SPI.begin(OLED_SCK_PIN, -1, OLED_MOSI_PIN, OLED_CS_PIN);
  if (!display.begin(SSD1306_SWITCHCAPVCC)) {
    Serial.println(F("SSD1306 not found"));
    for (;;) delay(10);
  }
  voiceSerial.begin(115200, SERIAL_8N1, VC02_RX_PIN, VC02_TX_PIN);
  drawScreen();
}

void loop() {
  bool reading = digitalRead(TOUCH_PIN) == HIGH;
  if (reading != lastTouchReading) {
    touchChangedAt = millis();
    lastTouchReading = reading;
  }

  if ((millis() - touchChangedAt) >= TOUCH_DEBOUNCE_MS && reading != touchState) {
    touchState = reading;
    if (touchState) {
      statusLine = "Hello! Listening...";
      packetLine = "Speak to VC-02";
      messageShownAt = millis();
      drawScreen();
    }
  }

  if (voiceSerial.available()) showVoicePacket();

  if (statusLine != "Ready" && millis() - messageShownAt >= MESSAGE_HOLD_MS) {
    statusLine = "Ready";
    packetLine = "Touch to wake";
    drawScreen();
  }
}