Desk Air Quality Buddy

#include <Wire.h>
#include <SPI.h>
#include <DHT.h>
#include <Adafruit_GFX.h>
#include <Adafruit_GC9A01A.h>
#include <MPU6050.h>
#include <driver/i2s.h>
#include <math.h>

constexpr int I2C_SDA = 0;
constexpr int I2C_SCL = 1;
constexpr int DHT_PIN = 3;
constexpr int TFT_DC = 2;
constexpr int TFT_SCK = 4;
constexpr int AUDIO_BCLK = 5;
constexpr int TFT_MOSI = 6;
constexpr int TFT_CS = 7;
constexpr int AUDIO_DOUT = 10;
constexpr int AUDIO_WS = 20;
constexpr int MIC_DATA = 21;
constexpr int AUDIO_SAMPLE_RATE = 16000;

DHT dht(DHT_PIN, DHT11);
MPU6050 mpu;
Adafruit_GC9A01A display(TFT_CS, TFT_DC, -1);

bool imuReady = false;
float shownTemperature = NAN;
float shownHumidity = NAN;
uint32_t shownSound = UINT32_MAX;
bool shownMoving = false;
bool humidityAlarmActive = false;
unsigned long lastSampleMs = 0;

void setupAudio() {
  i2s_config_t config = {};
  config.mode = (i2s_mode_t)(I2S_MODE_MASTER | I2S_MODE_TX | I2S_MODE_RX);
  config.sample_rate = AUDIO_SAMPLE_RATE;
  config.bits_per_sample = I2S_BITS_PER_SAMPLE_32BIT;
  config.channel_format = I2S_CHANNEL_FMT_ONLY_LEFT;
  config.communication_format = I2S_COMM_FORMAT_STAND_I2S;
  config.intr_alloc_flags = 0;
  config.dma_buf_count = 4;
  config.dma_buf_len = 128;
  config.use_apll = false;
  config.tx_desc_auto_clear = true;
  config.fixed_mclk = 0;
  i2s_driver_install(I2S_NUM_0, &config, 0, nullptr);

  i2s_pin_config_t pins = {};
  pins.bck_io_num = AUDIO_BCLK;
  pins.ws_io_num = AUDIO_WS;
  pins.data_out_num = AUDIO_DOUT;
  pins.data_in_num = MIC_DATA;
  i2s_set_pin(I2S_NUM_0, &pins);
}

void playBeep(uint16_t frequency, uint16_t durationMs) {
  const int sampleCount = (AUDIO_SAMPLE_RATE * durationMs) / 1000;
  for (int i = 0; i < sampleCount; ++i) {
    float phase = 2.0f * PI * frequency * i / AUDIO_SAMPLE_RATE;
    int32_t sample = (int32_t)(sinf(phase) * 70000000.0f);
    size_t written = 0;
    i2s_write(I2S_NUM_0, &sample, sizeof(sample), &written, portMAX_DELAY);
  }
}

uint32_t readSoundLevel() {
  int32_t sample = 0;
  size_t bytesRead = 0;
  int64_t total = 0;
  int validSamples = 0;
  for (int i = 0; i < 48; ++i) {
    i2s_read(I2S_NUM_0, &sample, sizeof(sample), &bytesRead, 20 / portTICK_PERIOD_MS);
    if (bytesRead == sizeof(sample)) {
      total += abs(sample >> 14);
      ++validSamples;
    }
  }
  return validSamples ? total / validSamples : 0;
}

bool isMoving() {
  if (!imuReady) return false;
  int16_t ax, ay, az, gx, gy, gz;
  mpu.getMotion6(&ax, &ay, &az, &gx, &gy, &gz);
  return abs(gx) > 900 || abs(gy) > 900 || abs(gz) > 900;
}

void drawDashboard(float temperature, float humidity, uint32_t sound, bool moving) {
  display.fillScreen(GC9A01A_BLACK);
  display.setTextWrap(false);
  display.setTextColor(GC9A01A_CYAN);
  display.setTextSize(2);
  display.setCursor(48, 28);
  display.print("DESK");
  display.setCursor(43, 48);
  display.print("BUDDY");

  display.drawRoundRect(18, 78, 204, 42, 10, GC9A01A_BLUE);
  display.setTextColor(GC9A01A_WHITE);
  display.setTextSize(2);
  display.setCursor(31, 90);
  if (isnan(temperature) || isnan(humidity)) {
    display.print("DHT11 ERROR");
  } else {
    display.printf("%2.0fC  %2.0f%%", temperature, humidity);
  }

  display.drawRoundRect(18, 130, 204, 30, 8, GC9A01A_DARKGREY);
  display.setTextSize(1);
  display.setCursor(32, 140);
  display.printf("SOUND %lu", (unsigned long)sound);

  display.setTextColor(moving ? GC9A01A_YELLOW : GC9A01A_GREEN);
  display.setTextSize(2);
  display.setCursor(55, 184);
  display.print(moving ? "MOVING" : "STILL");
}

void setup() {
  Serial.begin(115200);
  Wire.begin(I2C_SDA, I2C_SCL);
  dht.begin();

  mpu.initialize();
  imuReady = mpu.testConnection();

  SPI.begin(TFT_SCK, -1, TFT_MOSI, TFT_CS);
  display.begin();
  display.setRotation(0);
  drawDashboard(NAN, NAN, 0, false);

  setupAudio();
  playBeep(1200, 90);
  Serial.println("DeskBuddy ready");
}

void loop() {
  if (millis() - lastSampleMs < 2000) return;
  lastSampleMs = millis();

  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();
  uint32_t sound = readSoundLevel();
  bool moving = isMoving();

  bool changed = isnan(temperature) != isnan(shownTemperature) ||
                 isnan(humidity) != isnan(shownHumidity) ||
                 (!isnan(temperature) && abs(temperature - shownTemperature) >= 0.5f) ||
                 (!isnan(humidity) && abs(humidity - shownHumidity) >= 1.0f) ||
                 abs((int32_t)sound - (int32_t)shownSound) >= 25 ||
                 moving != shownMoving;
  if (changed) {
    drawDashboard(temperature, humidity, sound, moving);
    shownTemperature = temperature;
    shownHumidity = humidity;
    shownSound = sound;
    shownMoving = moving;
  }

  bool humidityHigh = !isnan(humidity) && humidity >= 70.0f;
  if (humidityHigh && !humidityAlarmActive) {
    playBeep(850, 180);
  }
  humidityAlarmActive = humidityHigh;

  Serial.printf("Temp %.1f C, humidity %.1f%%, sound %lu, %s, MPU %s\n",
                temperature, humidity, (unsigned long)sound,
                moving ? "moving" : "still", imuReady ? "ready" : "not found");
}