Smart home hub on an ESP32-C3

/*
 * Smart home hub: a web dashboard for lights, a fan, sensors and schedules.
 *
 * Switch a lamp and a fan through relays and dim a porch light from a web
 * page. A DHT22 and a PIR run the automatic modes, a DS3231 clock runs the
 * porch light's schedule, and a 16x2 LCD shows the status.
 *
 * The dashboard is this sketch's own WebServer. Press Run, open the Web tab
 * and use the buttons. The NETWORK under it is SIMULATED: no radio and no
 * listening socket, and only the Web tab in this page can reach
 * http://192.168.4.2/. The handlers and the pins are real code on the core.
 *
 * Every switch works from the Serial Monitor too: type "lamp on",
 * "fan auto" or "porch 40" and press Enter.
 *
 * Wiring (ESP32-C3-DevKitM-1):
 *   relay module IN1 -> GPIO 19 (the lamp), IN2 -> GPIO 18 (the fan). The
 *   module is active LOW, as most are: a LOW input pulls the coil in.
 *   porch light -> GPIO 10 through 100 ohms, dimmed with PWM
 *   DHT22 data -> GPIO 4 (from 3V3), PIR out -> GPIO 5 (from 5 V)
 *   DS3231 and LCD on I2C: SDA GPIO 1, SCL GPIO 0, both from 3V3
 */
#include <WiFi.h>
#include <WebServer.h>
#include <DHT.h>
#include <Wire.h>
#include <RTClib.h>
#include <LiquidCrystal_I2C.h>

const char *SSID = "Mokxi-Lab";
const char *PASSWORD = "breadboard";

const uint8_t LAMP_RELAY = 19;
const uint8_t FAN_RELAY = 18;
const uint8_t PORCH = 10;
const uint8_t DHT_PIN = 4;
const uint8_t PIR_PIN = 5;

enum Mode : uint8_t { OFF, ON, AUTO };
const char *const MODE_NAMES[3] = {"off", "on", "auto"};

WebServer server(80);
Mode lampMode = OFF;
Mode fanMode = OFF;
bool lampOn = false;
bool fanOn = false;
int porchLevel = 0;  // percent

DHT dht(DHT_PIN, DHT22);
float temperature = NAN;
float humidity = NAN;
float fanAbove = 26.0;                    // AUTO turns the fan on at this, in C
const unsigned long LAMP_HOLD_MS = 60000; // AUTO keeps the lamp on after motion
bool motion = false;
bool seenMotion = false;
unsigned long motionAt = 0;
unsigned long readAt = 0;
RTC_DS3231 rtc;
LiquidCrystal_I2C lcd(0x27, 16, 2);
int porchOnAt = 18 * 60;   // minutes after midnight
int porchOffAt = 23 * 60;
int porchScheduled = 60;   // the brightness the schedule sets, percent
int lastMinute = -1;
unsigned long lcdAt = 0;

// ---- outputs ----------------------------------------------------------------

void setRelay(uint8_t pin, bool on) {
  digitalWrite(pin, on ? LOW : HIGH);  // active LOW
}

void applyOutputs() {
  bool lamp = lampMode == ON;
  bool fan = fanMode == ON;
  if (lampMode == AUTO) {
    lamp = seenMotion && millis() - motionAt < LAMP_HOLD_MS;
  }
  if (fanMode == AUTO && !isnan(temperature)) {
    // Half a degree of hysteresis, so the fan does not chatter at the line.
    fan = fanOn ? temperature > fanAbove - 0.5 : temperature >= fanAbove;
  }
  if (lamp != lampOn) {
    lampOn = lamp;
    setRelay(LAMP_RELAY, lampOn);
    Serial.print("lamp ");
    Serial.print(lampOn ? "on" : "off");
    Serial.print(" (");
    Serial.print(MODE_NAMES[lampMode]);
    Serial.println(")");
  }
  if (fan != fanOn) {
    fanOn = fan;
    setRelay(FAN_RELAY, fanOn);
    Serial.print("fan ");
    Serial.print(fanOn ? "on" : "off");
    Serial.print(" (");
    Serial.print(MODE_NAMES[fanMode]);
    Serial.println(")");
  }
}

void setPorch(int level, const char *why) {
  porchLevel = constrain(level, 0, 100);
  analogWrite(PORCH, porchLevel * 255 / 100);
  Serial.print("porch ");
  Serial.print(porchLevel);
  Serial.print("% (");
  Serial.print(why);
  Serial.println(")");
}

Mode parseMode(const String &s) {
  if (s == "on") return ON;
  if (s == "auto") return AUTO;
  return OFF;
}

String hhmm(int minutes) {
  char text[6];
  snprintf(text, sizeof text, "%02d:%02d", minutes / 60, minutes % 60);
  return String(text);
}

int parseHhmm(const String &s, int fallback) {
  int colon = s.indexOf(':');
  if (colon < 1) return fallback;
  int h = s.substring(0, colon).toInt();
  int m = s.substring(colon + 1).toInt();
  if (h < 0 || h > 23 || m < 0 || m > 59) return fallback;
  return h * 60 + m;
}

// ---- the dashboard ----------------------------------------------------------

void modeButtons(String &p, const char *path, Mode current) {
  p += "<form method=\"post\" action=\"";
  p += path;
  p += "\">";
  const uint8_t modes = 3;
  for (uint8_t m = 0; m < modes; m++) {
    p += "<button name=\"mode\" value=\"";
    p += MODE_NAMES[m];
    p += m == current ? "\" class=\"on\">" : "\">";
    p += MODE_NAMES[m];
    p += "</button>";
  }
  p += "</form>";
}

void sendPage() {
  String p;
  p.reserve(3000);
  p += "<!doctype html><html><body><style>"
       "body{font-family:system-ui,sans-serif;margin:16px;background:#f4f5f7;color:#1d2026}"
       ".card{background:#fff;border-radius:14px;padding:12px 16px;margin:0 0 12px}"
       "h1{font-size:22px;margin:0 0 12px}h2{font-size:14px;margin:0 0 6px;color:#5a6270}"
       ".big{font-size:26px;font-weight:600}button{font:inherit;padding:5px 12px;margin:2px;"
       "border-radius:8px;border:1px solid #c9ced8;background:#fff}"
       "button.on{background:#2f6fec;color:#fff;border-color:#2f6fec}small{color:#5a6270}"
       "</style><h1>Home</h1>";
  DateTime now = rtc.now();
  p += "<div class=\"card\"><h2>Time</h2><div class=\"big\">";
  p += hhmm(now.hour() * 60 + now.minute());
  p += "</div></div>";
  p += "<div class=\"card\"><h2>Climate</h2><div class=\"big\">";
  if (isnan(temperature)) {
    p += "reading...";
  } else {
    p += String(temperature, 1);
    p += " &deg;C &middot; ";
    p += String(humidity, 0);
    p += "%";
  }
  p += "</div><small>";
  if (seenMotion) {
    p += "Motion ";
    p += String((millis() - motionAt) / 1000);
    p += " s ago";
  } else {
    p += "No motion yet";
  }
  p += "</small></div>";
  p += "<div class=\"card\"><h2>Lamp: ";
  p += lampOn ? "on" : "off";
  p += "</h2>";
  modeButtons(p, "/lamp", lampMode);
  p += "<small>Auto: on for a minute after motion.</small>";
  p += "</div><div class=\"card\"><h2>Fan: ";
  p += fanOn ? "on" : "off";
  p += "</h2>";
  modeButtons(p, "/fan", fanMode);
  p += "<form method=\"post\" action=\"/fan\"><small>Auto at </small><input type=\"number\" name=\"above\" step=\"0.5\" value=\"";
  p += String(fanAbove, 1);
  p += "\"><small> &deg;C </small><button>Set</button></form>";
  p += "</div><div class=\"card\"><h2>Porch light: ";
  p += String(porchLevel);
  p += "%</h2><form method=\"post\" action=\"/porch\"><input type=\"range\" name=\"level\" min=\"0\" max=\"100\" value=\"";
  p += String(porchLevel);
  p += "\"><button>Set</button></form>";
  p += "<form method=\"post\" action=\"/schedule\"><small>On at </small><input type=\"time\" name=\"on\" value=\"";
  p += hhmm(porchOnAt);
  p += "\"><small> off at </small><input type=\"time\" name=\"off\" value=\"";
  p += hhmm(porchOffAt);
  p += "\"><button>Save</button></form>";
  p += "</div><small>Served by the sketch on a simulated network.</small></body></html>";
  server.send(200, "text/html", p);
}

void handleRoot() { sendPage(); }

void handleLamp() {
  if (server.hasArg("mode")) lampMode = parseMode(server.arg("mode"));
  applyOutputs();
  sendPage();
}

void handleFan() {
  if (server.hasArg("mode")) fanMode = parseMode(server.arg("mode"));
  if (server.hasArg("above")) {
    fanAbove = server.arg("above").toFloat();
    Serial.print("fan auto at ");
    Serial.print(fanAbove, 1);
    Serial.println(" C");
  }
  applyOutputs();
  sendPage();
}

void handlePorch() {
  if (server.hasArg("level")) setPorch(server.arg("level").toInt(), "dashboard");
  sendPage();
}

void handleSchedule() {
  porchOnAt = parseHhmm(server.arg("on"), porchOnAt);
  porchOffAt = parseHhmm(server.arg("off"), porchOffAt);
  Serial.print("schedule: porch on at ");
  Serial.print(hhmm(porchOnAt));
  Serial.print(", off at ");
  Serial.println(hhmm(porchOffAt));
  sendPage();
}

// ---- the Serial Monitor -------------------------------------------------------

void readCommand() {
  if (!Serial.available()) return;
  String line = Serial.readStringUntil('\n');
  line.trim();
  int space = line.indexOf(' ');
  String what = space < 0 ? line : line.substring(0, space);
  String value = space < 0 ? String("") : line.substring(space + 1);
  if (what == "lamp") {
    lampMode = parseMode(value);
    applyOutputs();
  } else if (what == "fan") {
    fanMode = parseMode(value);
    applyOutputs();
  } else if (what == "porch") {
    setPorch(value.toInt(), "serial");
  } else if (line.length() > 0) {
    Serial.println("try: lamp on, fan off, porch 40");
  }
}

// ---- sensors ------------------------------------------------------------------

void readSensors() {
  bool now = digitalRead(PIR_PIN) == HIGH;
  if (now && !motion) {
    Serial.println("motion");
    seenMotion = true;
  }
  if (now) motionAt = millis();
  motion = now;

  // The DHT22 gives a new reading at most every two seconds.
  if (millis() - readAt < 2000 && readAt != 0) return;
  readAt = millis();
  float t = dht.readTemperature();
  float h = dht.readHumidity();
  if (isnan(t) || isnan(h)) return;
  bool first = isnan(temperature);
  if (first || fabs(t - temperature) >= 0.5 || fabs(h - humidity) >= 2) {
    Serial.print("climate ");
    Serial.print(t, 1);
    Serial.print(" C, ");
    Serial.print(h, 0);
    Serial.println("% humidity");
  }
  temperature = t;
  humidity = h;
}

// ---- the clock, the schedule and the screen ---------------------------------------

void runSchedule() {
  DateTime now = rtc.now();
  int minute = now.hour() * 60 + now.minute();
  if (minute == lastMinute) return;
  lastMinute = minute;
  if (minute == porchOnAt) {
    Serial.print(hhmm(minute));
    Serial.print(" schedule: ");
    setPorch(porchScheduled, "schedule");
  }
  if (minute == porchOffAt) {
    Serial.print(hhmm(minute));
    Serial.print(" schedule: ");
    setPorch(0, "schedule");
  }
}

void drawLcd() {
  if (millis() - lcdAt < 1000) return;
  lcdAt = millis();
  DateTime now = rtc.now();
  char top[17];
  char bottom[17];
  int t = isnan(temperature) ? 0 : (int)(temperature * 10 + 0.5);
  int h = isnan(humidity) ? 0 : (int)(humidity + 0.5);
  snprintf(top, sizeof top, "%02d:%02d %2d.%dC %3d%%", now.hour(), now.minute(), t / 10, t % 10, h);
  snprintf(bottom, sizeof bottom, "L:%-3s F:%-3s P%3d", lampOn ? "on" : "off", fanOn ? "on" : "off", porchLevel);
  lcd.setCursor(0, 0);
  lcd.print(top);
  lcd.setCursor(0, 1);
  lcd.print(bottom);
}

// ---- setup and loop ---------------------------------------------------------------

void setup() {
  Serial.begin(115200);
  pinMode(LAMP_RELAY, OUTPUT);
  pinMode(FAN_RELAY, OUTPUT);
  setRelay(LAMP_RELAY, false);
  setRelay(FAN_RELAY, false);
  pinMode(PORCH, OUTPUT);
  pinMode(PIR_PIN, INPUT);
  dht.begin();
  Wire.begin(1, 0);  // SDA on GPIO 1, SCL on GPIO 0
  if (!rtc.begin()) Serial.println("no clock on the I2C bus");
  lcd.init();
  lcd.print("Home hub");

  Serial.println("Simulated WiFi: only the Web panel can reach this server.");
  WiFi.begin(SSID, PASSWORD);
  while (WiFi.status() != WL_CONNECTED) {
    delay(250);
  }
  Serial.print("Home hub ready: open http://");
  Serial.print(WiFi.localIP());
  Serial.println("/ in the Web tab");

  server.on("/", handleRoot);
  server.on("/lamp", handleLamp);
  server.on("/fan", handleFan);
  server.on("/porch", handlePorch);
  server.on("/schedule", handleSchedule);
  server.begin();
}

void loop() {
  server.handleClient();
  readCommand();
  readSensors();
  applyOutputs();
  runSchedule();
  drawLcd();
  delay(2);
}