wrong ldr lux-calc (see Excel sheet, mixed x y )

lib/treppe/treppe.cpp

@@ -182,11 +182,12 @@ float Treppe::read_ldr()
          = 37280.00/analogRead(A0)
   ldr_ohm = R(LDR)
 
-  E(LDR) = 79.735 * R(LDR)^-0.498   (see Excel Regression)
+  E(LDR) = 6526.5 * R(LDR)^-2   (see Excel Regression)
+  E(LDR) = 6526.5 / (R(LDR)^2)
   ldr_value = E(LDR)
   */
   float ldr_ohm = 37280.00 / analogRead(A0);
-  float ldr_value = 79.735 * pow(ldr_ohm, -0.498);
+  float ldr_value = 6526.6/(ldr_ohm*ldr_ohm);
   return ldr_value;
 }
 

lib/treppe/treppe.h

@@ -5,7 +5,7 @@
 
 // #define LDRDEBUG  // comment in to override LDR measurement 
 
-#define LDR_HYS 5.0  // Hysteresis for switching off FSM [lux]
+#define LDR_HYS 1  // Hysteresis for switching off FSM [lux]
 
 #define SENSOR_OBEN 16
 #define SENSOR_UNTEN 12
@@ -21,7 +21,7 @@ private:
     uint16_t idle_pwm_internal = 0;
     uint16_t active_pwm = 700;
 
-    uint16_t ldr_schwelle = 7;      // activation value for FSM [lx]
+    uint16_t ldr_schwelle = 2;      // activation value for FSM [lx]
 
     uint16_t start_pwm = 0;
     uint16_t ziel_pwm  = 0;