Fixed broken OOR handling & Division by zero

Fixed broken out of range handling. ESP2862 would reset itself every minute under extreme low light conditions due to division by zero.
New method also correct the previously fixed range of 4900. Range is actually dependent on the chosen integration time.

_P015_TLS2561.ino

@@ -42,6 +42,11 @@ boolean Plugin_015_init = false;
 #define TSL2561_CHSCALE_TINT_120MS 0x0D6B // 322/96 * 2^CH_SCALE (120ms)
 #define TSL2561_CHSCALE_TINT_402MS (1 << TSL2561_CH_SCALE) // default No scaling
 
+// Clipping thresholds
+#define TSL2561_CLIPPING_13MS     (4900)
+#define TSL2561_CLIPPING_101MS    (37000)
+#define TSL2561_CLIPPING_402MS    (65000)
+
 #define TSL2561_K1T 0x0040   // 0.125 * 2^RATIO_SCALE
 #define TSL2561_B1T 0x01f2   // 0.0304 * 2^LUX_SCALE
 #define TSL2561_M1T 0x01be   // 0.0272 * 2^LUX_SCALE
@@ -260,19 +265,23 @@ int8_t Plugin_015_tsl2561_calcLux(uint8_t integration)
   unsigned long lux;
   unsigned int b, m;
   uint16_t ch0,ch1;
+  uint16_t clipThreshold;
   uint8_t msb, lsb;
   uint8_t err = 0;
 
   // do start calculation with speed integration time, 
   Plugin_015_tsl2561_writeRegister(TSL2561_TIMING, integration);  
   if (integration == TSL2561_TIMING_402MS ) {
     chScale = TSL2561_CHSCALE_TINT_402MS ;
+    clipThreshold = TSL2561_CLIPPING_402MS ;
     delay(405);
   } else if (integration == TSL2561_TIMING_101MS ) {
     chScale = TSL2561_CHSCALE_TINT_101MS ;
+    clipThreshold = TSL2561_CLIPPING_101MS ;
     delay(103);
   } else {
     chScale = TSL2561_CHSCALE_TINT_13MS ;
+    clipThreshold = TSL2561_CLIPPING_13MS ;
     delay(15);
   }
 
@@ -289,9 +298,11 @@ int8_t Plugin_015_tsl2561_calcLux(uint8_t integration)
   if( err )
     return -2; 
 
-  // ch0 out of range, but ch1 not. the lux is not valid in this situation.
-  if( ch0/ch1 < 2 && ch0 > 4900) 
-    return -1;  
+  /* Sensor saturated the lux is not valid in this situation */
+  if ((ch0 > clipThreshold) || (ch1 > clipThreshold))
+  {
+    return -1;
+  }
 
   // gain is 1 so put it to 16X
   chScale <<= 4;