Tiny Robot AI Assistant

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


// Forward declarations
void drawEye(int centerX, bool happy);
void drawFace(const char *message, bool happy);
int readSoundLevel();
void playRobotReply();

constexpr int OLED_SDA_PIN = 4;
constexpr int OLED_SCL_PIN = 5;
constexpr int MIC_PIN = 26;
constexpr int SPEAKER_PIN = 6;
constexpr uint8_t SCREEN_WIDTH = 128;
constexpr uint8_t SCREEN_HEIGHT = 64;
constexpr uint8_t OLED_ADDRESS = 0x3C;
constexpr unsigned long SAMPLE_WINDOW_MS = 45;
constexpr unsigned long REPLY_COOLDOWN_MS = 1800;
constexpr int SOUND_THRESHOLD = 115;

Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, -1);
unsigned long lastReplyAt = 0;

void drawEye(int centerX, bool happy) {
  display.fillRoundRect(centerX - 11, 18, 22, 21, 8, SSD1306_WHITE);
  display.fillCircle(centerX, happy ? 27 : 29, 5, SSD1306_BLACK);
  display.fillCircle(centerX + 2, happy ? 25 : 27, 2, SSD1306_WHITE);
}

void drawFace(const char *message, bool happy) {
  display.clearDisplay();
  display.drawRoundRect(1, 1, 126, 62, 9, SSD1306_WHITE);
  display.fillRoundRect(51, 4, 26, 4, 2, SSD1306_WHITE);
  drawEye(35, happy);
  drawEye(93, happy);
  if (happy) {
    display.drawLine(53, 46, 75, 46, SSD1306_WHITE);
    display.drawPixel(52, 45, SSD1306_WHITE);
    display.drawPixel(76, 45, SSD1306_WHITE);
  } else {
    display.drawLine(54, 48, 74, 48, SSD1306_WHITE);
  }
  display.setTextColor(SSD1306_WHITE);
  display.setTextSize(1);
  const int16_t textX = (128 - strlen(message) * 6) / 2;
  display.setCursor(textX, 53);
  display.print(message);
  display.display();
}

int readSoundLevel() {
  int lowValue = 1023;
  int highValue = 0;
  const unsigned long started = millis();
  while (millis() - started < SAMPLE_WINDOW_MS) {
    const int value = analogRead(MIC_PIN);
    if (value < lowValue) lowValue = value;
    if (value > highValue) highValue = value;
  }
  return highValue - lowValue;
}

void playRobotReply() {
  tone(SPEAKER_PIN, 660, 120);
  delay(145);
  tone(SPEAKER_PIN, 880, 160);
  delay(185);
  tone(SPEAKER_PIN, 1047, 220);
  delay(245);
  noTone(SPEAKER_PIN);
}

void setup() {
  pinMode(MIC_PIN, INPUT);
  pinMode(SPEAKER_PIN, OUTPUT);
  analogReadResolution(10);
Wire.begin();

  if (!display.begin(SSD1306_SWITCHCAPVCC, OLED_ADDRESS)) {
    for (;;) delay(1000);
  }
  drawFace("SAY HELLO", false);
}

void loop() {
  const int soundLevel = readSoundLevel();
  const unsigned long now = millis();
  if (soundLevel >= SOUND_THRESHOLD && now - lastReplyAt >= REPLY_COOLDOWN_MS) {
    lastReplyAt = now;
    drawFace("I HEAR YOU", true);
    playRobotReply();
    drawFace("SAY HELLO", false);
  }
}