adding the BH1750 from their downloads

BH1750/examples/BH1750advanced/BH1750advanced.ino

@@ -0,0 +1,95 @@
+/*
+
+  Advanced BH1750 library usage example
+
+  This example has some comments about advanced usage features.
+
+  Connection:
+
+    VCC -> 3V3 or 5V
+    GND -> GND
+    SCL -> SCL (A5 on Arduino Uno, Leonardo, etc or 21 on Mega and Due, on esp8266 free selectable)
+    SDA -> SDA (A4 on Arduino Uno, Leonardo, etc or 20 on Mega and Due, on esp8266 free selectable)
+    ADD -> (not connected) or GND
+
+  ADD pin is used to set sensor I2C address. If it has voltage greater or equal to
+  0.7VCC voltage (e.g. you've connected it to VCC) the sensor address will be
+  0x5C. In other case (if ADD voltage less than 0.7 * VCC) the sensor address will
+  be 0x23 (by default).
+
+*/
+
+#include <Wire.h>
+#include <BH1750.h>
+
+/*
+  BH1750 can be physically configured to use two I2C addresses:
+    - 0x23 (most common) (if ADD pin had < 0.7VCC voltage)
+    - 0x5C (if ADD pin had > 0.7VCC voltage)
+
+  Library uses 0x23 address as default, but you can define any other address.
+  If you had troubles with default value - try to change it to 0x5C.
+
+*/
+BH1750 lightMeter(0x23);
+
+void setup(){
+
+  Serial.begin(9600);
+
+  // Initialize the I2C bus (BH1750 library doesn't do this automatically)
+  Wire.begin();
+  // On esp8266 you can select SCL and SDA pins using Wire.begin(D4, D3);
+
+  /*
+
+    BH1750 has six different measurement modes. They are divided in two groups;
+    continuous and one-time measurements. In continuous mode, sensor continuously
+    measures lightness value. In one-time mode the sensor makes only one
+    measurement and then goes into Power Down mode.
+
+    Each mode, has three different precisions:
+
+      - Low Resolution Mode - (4 lx precision, 16ms measurement time)
+      - High Resolution Mode - (1 lx precision, 120ms measurement time)
+      - High Resolution Mode 2 - (0.5 lx precision, 120ms measurement time)
+
+    By default, the library uses Continuous High Resolution Mode, but you can
+    set any other mode, by passing it to BH1750.begin() or BH1750.configure()
+    functions.
+
+    [!] Remember, if you use One-Time mode, your sensor will go to Power Down
+    mode each time, when it completes a measurement and you've read it.
+
+    Full mode list:
+
+      BH1750_CONTINUOUS_LOW_RES_MODE
+      BH1750_CONTINUOUS_HIGH_RES_MODE (default)
+      BH1750_CONTINUOUS_HIGH_RES_MODE_2
+
+      BH1750_ONE_TIME_LOW_RES_MODE
+      BH1750_ONE_TIME_HIGH_RES_MODE
+      BH1750_ONE_TIME_HIGH_RES_MODE_2
+
+  */
+
+  // begin returns a boolean that can be used to detect setup problems.
+  if (lightMeter.begin(BH1750::CONTINUOUS_HIGH_RES_MODE)) {
+    Serial.println(F("BH1750 Advanced begin"));
+  }
+  else {
+    Serial.println(F("Error initialising BH1750"));
+  }
+
+}
+
+
+void loop() {
+  if (lightMeter.measurementReady()) {
+    float lux = lightMeter.readLightLevel();
+    Serial.print("Light: ");
+    Serial.print(lux);
+    Serial.println(" lx");
+  }
+
+}