new ldr algo

lib/treppe/treppe.cpp

   E(LDR) = 6526.5 / (R(LDR)^2)
   ldr_value = E(LDR)
   */
-  float ldr_ohm = 37280.00 / analogRead(A0);
+  //float ldr_ohm = 37280.00 / analogRead(A0);
+  float voltage = analogRead(A0)*0.0036;
+  float ldr_ohm = 40.57*(3.3-voltage)/voltage;
   float ldr_value = 6526.6 / (ldr_ohm * ldr_ohm);
+  #ifdef LDRDEBUG
+  Serial.printf("Ohm: %f lux: %f\n", ldr_ohm,ldr_value);
+  #endif
   return ldr_value;
 }
 

lib/treppe/treppe.h

 #include <EEPROM.h>
 
 // #define LDRDEBUG  // comment in to override LDR measurement
-#define LDR_HYS 1 // Hysteresis for switching off FSM [lux]
+#define LDR_HYS 5 // Hysteresis for switching off FSM [lux]
 
 #define SENSOR_OBEN 16
 #define SENSOR_UNTEN 12