tinyhouse: Use LDR to react to external lightHEADmaster

This does three things:

* When it is too dark, the lights will go into a shut down mode, where
  the maximum amount of brightness is graudally reduced to zero. This will
  allow me to let the project run all the time, while shutting down when I
  go to bed.
* When it is dim (again), the process is reversed (but faster)
* When there is too much light, the lights will be directly set to zero.
  This means that the house won't be lit if I switch on the lights in my
  room.

1 files changed, 37 insertions, 5 deletions

diff --git a/lighting/tinyhouse.ino b/lighting/tinyhouse.ino
index f2bf4f8..b77e2fb 100644
--- a/lighting/tinyhouse.ino
+++ b/lighting/tinyhouse.ino
@@ -5,23 +5,55 @@ void setup() {
 
 int i = 127;
 int j = 127;
+int globalLimit = 255;
+int ldr = 0;
+int itercnt = 0;
+boolean powerDown = false;
+boolean powerUp   = false;
 
 void loop() {
+  itercnt++;
+  ldr = analogRead(A0);
+
+  if (ldr >= 1000 && globalLimit == 255) {
+    powerDown = true;
+    powerUp   = false;
+  } else if (ldr < 1000 && globalLimit == 0) {
+    powerDown = false;
+    powerUp   = true;
+  }
+
+  if (powerDown && globalLimit > 0) {
+    // slow shutdown
+    itercnt % 8 == 0 && globalLimit--;
+  } else if( powerUp && globalLimit < 255 ) {
+    // fast start
+    globalLimit++;
+  }
+
   delay(50);
 
   i = limit(i + (random(2) == 0 ? 8 : -8), 16);
   j = limit(j + (random(2) == 0 ? 2 : -2),  2);
 
-  analogWrite(3, j);
-  analogWrite(5, i);
+  if (ldr > 600) {
+    analogWrite(3, j);
+    analogWrite(5, i);
+  } else { // Simply go dark
+    analogWrite(3, 0);
+    analogWrite(5, 0);
+  }
 
 }
 
 int limit(int i, int within) {
-  if( i > (255 - within) )
-    return 255 - within;
+  if (globalLimit < within)
+    return 0;
+
+  if (i > (globalLimit - within))
+    return globalLimit - within;
 
-  if( i < within )
+  if (i < within)
     return within;
 
   return i;