implement incident bh1750 sensor and lux ev calculation

lightmeter.ino

@@ -28,19 +28,24 @@ BH1750 lightMeter;
 #define PIN_ON PB9
 #define TIME_AUTOPOWEROFF 120000
 #define LDRDELAY 50 //minimum delay between ldr readings. Transistor for lower value pulldown resistor switches in between
+#define INCIDENTDELAY 100 //minimum delay between incident sensor (BH1750) readings
 #define DEBOUNCETIME 50 //time to not check for inputs after key press
-#define BUTTONTIMEHOLD 1000 //time for button hold
+#define BUTTONTIMEHOLD 750 //time for button hold
 
 #define voltage_warn 3.4 //voltage per cell   //TODO implement warning
 
 //float shuttertimes1[]={1,1.0/2, 1.0/4, 1.0/8, 1.0/15, 1.0/30, 1.0/60, 1.0/125, 1.0/250, 1.0/500, 1.0/1000, 1.0/2000, 1.0/4000, 1.0/8000};
 float shuttertimes1[]={64,32,16,8,4,2,1,1.0/2, 1.0/4, 1.0/8, 1.0/15, 1.0/30, 1.0/60, 1.0/125, 1.0/250, 1.0/500, 1.0/1000, 1.0/2000, 1.0/4000, 1.0/8000};
+#define SHUTTERTIMES1_MAXINDEX 19
 String settingsnameShutterSelectionMode[]={"Analog"}; //names for tables
 #define MAXIMUM_SHUTTERSELECTIONMODES 1
 
 float aperaturesFull[]={1,1.4, 2, 2.8, 4, 5.6, 8, 11, 16, 22, 32};
+#define APERATURESFULL_MAXINDEX 10
 float aperaturesHalf[]={1, 1.2, 1.4, 1.7, 2, 2.4, 2.8, 3.4, 4, 4.8, 5.6, 6.7, 8, 9.5, 11, 13, 16, 19, 22};
+#define APERATURESHALF_MAXINDEX 18
 float aperaturesThird[]={1, 1.1, 1.2, 1.4, 1.6, 1.8, 2, 2.2, 2.5, 2.8, 3.2, 3.5, 4, 4.5, 5.0, 5.6, 6.3, 7.1, 8, 9, 10, 11, 13, 14, 16, 18, 20, 22, 25, 29, 32, 36, 40, 45};
+#define APERATURESTHIRD_MAXINDEX 33
 String settingsnameAperatureSelectionMode[]={"Full","Half","Third"}; //names for tables
 #define MAXIMUM_APERATURESELECTIONMODES 3
 
@@ -51,6 +56,7 @@ float isoThird[]={12,16,20,25,32,40,50,64,80,100,125,160,200,250,320,400,500,640
 
 long loopmillis=0; //only use one millis reading each loop
 long last_ldrReading=0;
+long last_incidentReading=0;
 long millis_lastchange=0;
 long millis_lastinput=0;
 
@@ -88,6 +94,7 @@ Settings userSettings= {1,1, 1,2};
 #define OLED_RESET 4
 Adafruit_SSD1306 display(OLED_RESET);
 
+uint16_t incident=0; //incident reading from bh1750
 uint16_t analog_low=0; //better for low light
 uint16_t analog_high=0; //better for bright light (higher pulldown resistor for ldr)
 float ev=0; //calculated EV from LDR readings (reflected) or from Luxmeter (incident)
@@ -112,6 +119,10 @@ String settingStrings[]={"ISO:","F-Stops:","Timetable:","Turn Off"};
 #define SETTINGS_SELECTEDITEM_MAX 3 //inclusive. 2 means 3 items available
 boolean settings_itemActive=false; //item in settings selected to change value
 
+#define METERINGMODE_REFLECTIVE 0
+#define METERINGMODE_INCIDENT 1
+uint8_t meteringmode=METERINGMODE_REFLECTIVE;
+
 
 char tempstring[16]; //for dtostrf  //dtostrf(modefactor,1,3,tempstring);
 
@@ -123,12 +134,13 @@ void setup()   {
   Serial.begin(9600);
   Serial.println("Started");
 
-
+  Serial.println("Init Display");
   display.begin(SSD1306_SWITCHCAPVCC, 0x3C);
   display.clearDisplay();
   display.display();
 
-  lightMeter.begin(BH1750_CONTINUOUS_HIGH_RES_MODE_2);
+  Serial.println("Init BH1750");
+  lightMeter.begin(BH1750_CONTINUOUS_HIGH_RES_MODE_2); //max reading=54612
   //set measurement time (for higher resolution) http://www.raspberry-pi-geek.de/Magazin/2015/04/Digital-Light-Sensor-BH1750-am-Raspberry-Pi
   //lightMeter.write8(71); //01000111 //high bit: 01000xxx   bits 7,6,5
   //lightMeter.write8(126); //01111110 //log bit: 011xxxxx   bits 4,3,2,1,0
@@ -159,9 +171,6 @@ void loop() {
 
 
   
-  uint16_t lux = lightMeter.readLightLevel();
-
-  
   handleInputs();
   
   calculateEV();
@@ -262,6 +271,7 @@ void handleInputs()
   //Voltage
   vbat=map(analogRead(PIN_VBAT), 0,3910,0,8400)/1000.0; //180k and 300k voltage divider. 8,4V -> 3,15V=3910
 
+  //LDR
   if ( loopmillis-last_ldrReading>LDRDELAY )
   {
     if (!digitalRead(PIN_BRIGHTMODE)){
@@ -274,6 +284,16 @@ void handleInputs()
   }
 
   
+
+  //Lightsensor BH1750
+  if ( loopmillis-last_incidentReading>INCIDENTDELAY )
+  {
+    incident = lightMeter.readLightLevel(); //value in lux from sensor
+    last_incidentReading=loopmillis;
+  }
+  
+
+  
   //Test  asdf
   /*
   if ( !digitalRead(PIN_TRIGGER)  ) {
@@ -338,6 +358,13 @@ void handleInputs_Lightmeter()
   if ( button_hold_center  ) { //Go to Settings
     displaymode=settings;
   }
+  if ( button_center )  { //Change Refelctive - Incident
+    if (meteringmode == METERINGMODE_REFLECTIVE){
+      meteringmode = METERINGMODE_INCIDENT;
+    }else if (meteringmode == METERINGMODE_INCIDENT) {
+      meteringmode = METERINGMODE_REFLECTIVE;
+    }
+  }
   
   if (setShutter==0 && setAperature==0){ //Auto
     //Value Change
@@ -479,6 +506,7 @@ float reciprocFloat(float p){
 
 void calculateEV()
 {
+  if (meteringmode == METERINGMODE_REFLECTIVE){
     //ev=map(analog_low,500, 3500 ,500, 1400)/100.0; //for testing
     double highev=11.7400532 + 0.000216655133*analog_high + 0.00000111372253*pow(analog_high,2) + -0.000000000163800818 *pow(analog_high,3);
     double lowev=-0.763427709 + 0.0138031137*analog_low + -0.00000576990095*pow(analog_low,2) + 0.000000000871611285*pow(analog_low,3);
@@ -491,6 +519,9 @@ void calculateEV()
       float mix=min(1.0, max(0.0,(lowev-12.5)/(14-12.5))); //0 to 1, 0-> use only lowev, 1-> use only highev
       ev=lowev*(1-mix)+highev*mix;
     }
+  }else if (meteringmode == METERINGMODE_INCIDENT){
+    ev = luxToEv(incident);
+  }
 
   if (setAperature>0){ //Aperature Priority
     showAperature=setAperature; //use user set Aperature
@@ -506,6 +537,16 @@ void calculateEV()
   
 }
 
+double evToLux(double ev) {
+    return pow(2, ev) * 2.5;
+}
+double luxToEv(uint16_t lux){
+  if (lux <= 2){
+    return 0;
+  }
+  return log (lux/2.5) / log (2);
+}
+
 float calculateShutter(float pEv, uint16_t pIso, uint16_t pAperature) //returns calculated Shutter speed given Ev, ISO and Aperature
 {
   //EV = log2 ( 100* Aperature^2 / (ISO * Time ))
@@ -590,9 +631,26 @@ uint8_t findAperatureIndex(float pAperature,uint8_t pMethod) //find index of clo
   float _minDistance=90000;
   float _lastminDistance=100000;
   uint8_t _index=userSettings.minimumAperatureIndex;
+  uint8_t _maxindexpossible=0;
+  
+  switch(pMethod){
+    case 1:
+        _maxindexpossible=APERATURESFULL_MAXINDEX;
+      break;
+    case 2:
+        _maxindexpossible=APERATURESHALF_MAXINDEX;
+      break;
+    case 3:
+        _maxindexpossible=APERATURESTHIRD_MAXINDEX;
+      break;
+  }
 
   while (_lastminDistance>_minDistance) //until distance increases
   {
+    if (_index>_maxindexpossible){ //this index will be out of bounds
+      return _maxindexpossible;
+    }
+    
     _lastminDistance=_minDistance;
     
     switch(pMethod){
@@ -608,7 +666,8 @@ uint8_t findAperatureIndex(float pAperature,uint8_t pMethod) //find index of clo
     }
     _index++; //next
   }
-  return _index-2;
+  
+  return _index-2; //use index with closest value
 }
 
 
@@ -641,10 +700,21 @@ uint8_t findShutterIndex(float pShutter,uint8_t pMethod) //find index of closest
   float _minDistance=abs(pShutter-shuttertimes1[0]);
   float _lastminDistance=_minDistance;
   uint8_t _index=0;
+  uint8_t _maxindexpossible=0;
+  
+  switch(pMethod){
+    case 1:
+        _maxindexpossible=SHUTTERTIMES1_MAXINDEX;
+      break;
+  }
 
   
   while (_lastminDistance>=_minDistance) //until distance increases
   {
+    if (_index>_maxindexpossible){ //this index will be out of bounds
+      return _maxindexpossible;
+    }
+    
     _lastminDistance=_minDistance;
     
     switch(pMethod){
@@ -654,7 +724,8 @@ uint8_t findShutterIndex(float pShutter,uint8_t pMethod) //find index of closest
     }
     _index++; //next
   }
-  return _index-2;
+  
+  return _index-2; //use index with closest value
 }
 
 void changeISO(int8_t pchange){ //pchange>0 means more light exposure (brighter image), higher iso
@@ -801,6 +872,13 @@ void updateDisplay_Lightmeter() //Lightmeter display
   display.print("V ");
   display.print("Ev=");
   display.print(ev);
+  display.print(" |");
+  display.print(incident);
+
+  display.setTextSize(1);
+  display.setCursor(10,10);
+  display.print(meteringmode);
+  
 }
 
 void updateDisplay_Settings()