Add support for the BH1750 light meter sensor

WeatherStation.ino

@@ -35,6 +35,11 @@
 # include <DHT.h>
 #endif // DHT_TYPE
 
+#ifdef HAVE_BH1750
+# include <Wire.h>
+# include <BH1750.h>
+#endif // HAVE_BH1750
+
 ESP8266WebServer server(80);
 unsigned long last_update = 0;
 
@@ -48,6 +53,11 @@ float humidity = 0.0;
 bool raining = false;
 #endif // RAIN_PIN
 
+#ifdef HAVE_BH1750
+BH1750 light;
+float light_level = 0;
+#endif // HAVE_BH1750
+
 static const char TEXT_PLAIN[] PROGMEM = "text/plain";
 
 void
@@ -61,6 +71,7 @@ send_metrics()
 {
     static const size_t dht_size = 228;
     static const size_t rain_size = 86;
+    static const size_t light_size = 72;
 
     size_t message_size =
 #ifdef DHT_TYPE
@@ -69,6 +80,9 @@ send_metrics()
 #ifdef RAIN_PIN
         rain_size +
 #endif // RAIN_PIN
+#ifdef HAVE_BH1750
+        light_size +
+#endif // HAVE_BH1750
         1;
     char message[message_size];
 
@@ -86,12 +100,20 @@ send_metrics()
              "# TYPE raining gauge\n"
              "raining %d\n"
 #endif // RAIN_PIN
+#ifdef HAVE_BH1750
+           "# HELP light Ambient light, in lumens\n"
+           "# TYPE light gauge\n"
+           "light %.2f\n"
+#endif // HAVE_BH1750
 #ifdef DHT_TYPE
              , temperature, humidity
 #endif // DHT_TYPE
 #ifdef RAIN_PIN
              , raining ? 1 : 0
 #endif // RAIN_PIN
+#ifdef HAVE_BH1750
+             , light_level
+#endif // HAVE_BH1750
         );
 
     server.send(200, "text/plain; version=0.0.4; charset=utf-8", message);
@@ -147,6 +169,15 @@ setup()
     pinMode(RAIN_PIN, INPUT);
 #endif // RAIN_PIN
 
+#ifdef HAVE_BH1750
+    Wire.begin(I2C_SDA_PIN, I2C_SCL_PIN);
+
+    if (!light.begin()) {
+        Serial.println("Could not find the BH1750 sensor!");
+        stop();
+    }
+#endif // HAVE_BH1750
+
     Serial.println("All set, starting the loop.");
 }
 
@@ -165,6 +196,10 @@ read_sensors()
     raining = (digitalRead(RAIN_PIN) == HIGH);
 #endif
 
+#ifdef HAVE_BH1750
+    light_level = light.readLightLevel();
+#endif // HAVE_BH1750
+
     // Turn off the LED to indicate work is finished
     digitalWrite(LED_BUILTIN, HIGH);
 }

config.h.sample

@@ -53,3 +53,14 @@
 // #define RAIN_PIN line
 #undef RAIN_PIN
 //#define RAIN_PIN D0
+
+// Pins used for I²C communication.  You will be instructed below if you need
+// to uncomment these
+//#define I2C_SDA_PIN D1
+//#define I2C_SCL_PIN D2
+
+// If you have a BH1750 light level sensor, remove this #undef line and
+// uncomment the #define HAVE_BH1750 line.  You will also have to set the SDA
+// and SCL pins using the I2C_SDA_PIN and I2C_SCL_PIN defines above.
+#undef HAVE_BH1750
+//#define HAVE_BH1750