4. Room Comfort Station

Publish temperature, humidity, calculated heat index, and a readable comfort label. This separates raw measurements from derived information.

Level: Intermediate · Time: 40 minutes

Requirements and wiring

ESP32 and DHT22 module
DHT sensor library and Adafruit Unified Sensor

Connect VCC→3V3, GND→GND, and DATA→GPIO 4.

Complete sketch


#include <PxServ.h>
#include <DHT.h>
 
const char* WIFI_SSID = "your_wifi_ssid";
const char* WIFI_PASSWORD = "your_wifi_password";
const char* PXSERV_API_KEY = "your_pxserv_api_key";
const int DHT_PIN = 4;
 
PxServ client(PXSERV_API_KEY);
DHT dht(DHT_PIN, DHT22);
 
String comfortLabel(float temperature, float humidity) {
  if (temperature < 18) return "cool";
  if (temperature > 27 || humidity > 70) return "warm-humid";
  if (humidity < 30) return "dry";
  return "comfortable";
}
 
void setup() {
  Serial.begin(115200);
  dht.begin();
  PxServ::connectWifi(WIFI_SSID, WIFI_PASSWORD);
}
 
void loop() {
  float temperature = dht.readTemperature();
  float humidity = dht.readHumidity();
  if (isnan(temperature) || isnan(humidity)) {
    client.setData("comfort/sensor-status", "error");
    delay(5000);
    return;
  }
 
  float heatIndex = dht.computeHeatIndex(temperature, humidity, false);
  client.setData("comfort/temperature", String(temperature, 1));
  client.setData("comfort/humidity", String(humidity, 1));
  client.setData("comfort/heat-index", String(heatIndex, 1));
  client.setData("comfort/status", comfortLabel(temperature, humidity));
  client.setData("comfort/sensor-status", "normal");
  delay(15000);
}

Test and limits

Compare different rooms and verify invalid sensor data produces error. The labels are teaching thresholds, not a health or HVAC standard; document any thresholds you change.