add BH1750 sensor example

examples/osd/arduino-bh1750/BH1750FVI-master/LogGraph/LogGraph.ino

@@ -0,0 +1,36 @@
+#include <Wire.h>
+#include <BH1750FVI.h>
+
+BH1750FVI eye;
+
+void setup() {
+  Wire.begin();
+  Serial.begin(115200);
+  //setup with continuous sampling, using the low address and double sensitivity
+  eye.begin(BH_ContH, BH_AddrL, 2.0);
+}
+
+void loop() {
+  //test if the sensor has had time to produce a new reading
+  if(eye.sampleIsFresh()){
+    //read the calibration-adjusted value, according to the sensitivity setting
+    word value = eye.getLightLevel('c');
+    logarithmicGraphing(value);
+    Serial.println(value);
+  }
+}
+
+
+
+
+void logarithmicGraphing(word value){
+  int i=0;
+  while(value>>i){
+    i++;
+    Serial.print("  ");
+  }
+  if(i>=2){
+    i=i-2;
+    if(value&(1<<i))Serial.print(' ');
+  }
+}