Add support for the DHT11/DHT22 sensors

WeatherStation.ino

@@ -31,7 +31,18 @@
 
 #include "config.h"
 
+#ifdef DHT_TYPE
+# include <DHT.h>
+#endif // DHT_TYPE
+
 ESP8266WebServer server(80);
+unsigned long last_update = 0;
+
+#ifdef DHT_TYPE
+DHT dht(DHT_PIN, DHT_TYPE);
+float temperature = 0.0;
+float humidity = 0.0;
+#endif // DHT_TYPE
 
 static const char TEXT_PLAIN[] PROGMEM = "text/plain";
 
@@ -44,9 +55,26 @@ reply_not_found()
 void
 send_metrics()
 {
-    char message[1];
+    static const size_t dht_size = 228;
+    char message[dht_size + 1];
 
-    snprintf(message, 1, "");
+    size_t message_size =
+#ifdef DHT_TYPE
+        dht_size +
+#endif // DHT_TYPE
+        1;
+
+    snprintf(message, message_size,
+#ifdef DHT_TYPE
+             "# HELP temperature_celsius Temperature in degrees Celsius\n"
+             "# TYPE temperature_celsius gauge\n"
+             "temperature_celsius %.2f\n"
+             "# HELP relative_humidity Relative humidity, in percents\n"
+             "# TYPE relative_humidity gauge\n"
+             "relative_humidity %.2f\n",
+             temperature, humidity
+#endif // DHT_TYPE
+        );
 
     server.send(200, "text/plain; version=0.0.4; charset=utf-8", message);
 }
@@ -86,12 +114,40 @@ setup()
 
     MDNS.addService("http", "tcp", 80);
 
+    // Initialize sensors
+#ifdef DHT_TYPE
+    dht.begin();
+#endif // DHT_TYPE
+
     Serial.println("All set, starting the loop.");
 }
 
+void
+read_sensors()
+{
+    // Turn on the LED to indicate that we’re working
+    digitalWrite(LED_BUILTIN, LOW);
+
+#ifdef DHT_TYPE
+    temperature = dht.readTemperature();
+    humidity = dht.readHumidity();
+#endif
+
+    // Turn off the LED to indicate work is finished
+    digitalWrite(LED_BUILTIN, HIGH);
+}
+
 void
 loop()
 {
+    unsigned long now = millis();
+
     MDNS.update();
     server.handleClient();
+
+    if (now - last_update >= 5000) {
+        read_sensors();
+
+        last_update = now;
+    }
 }

config.h.sample

@@ -32,3 +32,18 @@
 // different for each station you install (e.g. if you want to measure the
 // temperature and humidity of each room separately)
 #define MDNS_NAME "internal-hostname"
+
+// If you have a DHT temperature+humidity sensor of this type will be used,
+// remove the #undef line and uncomment one of DHT11 or DHT22.  You also have
+// to define the PIN your DHT sensor’s data (usually marked as DAT) is
+// connected to.
+//
+// DHT11 sensors are usually blue, and don’t work under freezing point
+// (0°C/32°F)
+//
+// DHT22 sensors are usually white and slightly bigger than DHT11 ones.  They
+// work well under freezing point (usually above -40°C/-40°F)
+#undef DHT_TYPE
+//#define DHT_TYPE DHT11
+//#define DHT_TYPE DHT22
+//#define DHT_PIN D5