diff --git a/avr/apps/ma_light/README b/avr/apps/ma_light/README
index aad3d56..0ecc796 100644
--- a/avr/apps/ma_light/README
+++ b/avr/apps/ma_light/README
@@ -12,23 +12,15 @@ turned off again.
 Typical usage is to watch for a motion message from some node with a motion sensor and react to that.
 This app can watch for up to two node-value pairs.
 
+This app can also watch for brightness sensor messages to only turn on light if it is dark enough.
+
 
 
 1. Values
 ======
 
-1.1 MALRGBWVALUE
-----------------
 
-RGB Value for activated light:
- aqhome-tool setdata -N nodes/XXXXXXXX/MALRGBWVALUE -v GRWB
-
-Example:
-  Set color of LED strip to blue (half intensity)
-  aqhome-tool setdata -N nodes/12345678/MALRGBWVALUE -v 0x80
-
-
-1.2 MALONTIME
+1.1 MALONTIME
 -------------
 On-Time after activation:
  aqhome-tool setdata -N nodes/XXXXXXXX/MALONTIME TIME_IN_1/10_SECS
@@ -38,7 +30,7 @@ Example:
  aqhome-tool setdata -N nodes/12345678/MALONTIME -v 200
 
 
-1.3. MALSOURCE1, MALSOURCE2
+1.2. MALSOURCE1, MALSOURCE2
 ---------------------------
 
 Sources for Motion Messages:
@@ -53,4 +45,36 @@ Example:
  aqhome-tool setdata -N nodes/12345678/MALSOURCE1 -v 0x0702
 
 
+1.3. MALSOURCEB
+---------------------------
+
+Source for Birightness Messages:
+ aqhome-tool setdata -N nodes/XXXXXXXX/MALSOURCEB -v VVNN
+
+ VVNN is a 16-bit value, lower 8 bit contain the source node address, higher 8 bit contain the
+ value id to react to.
+
+ If no brightness source is given (i.e. NN part is 0) then brightness will be ignored.
+
+Example:
+ React to value report messages with value id 0b (LIGHT) from node with address 2
+ aqhome-tool setdata -N nodes/12345678/MALSOURCEB -v 0x0b02
+
+
+1.4. MALVALUEB
+---------------------------
+
+Brightness value below which light is to be turned on.
+ aqhome-tool setdata -N nodes/XXXXXXXX/MALVALUEB -v NN
+
+The value highly depends on the type of sensor. Those photodiodes used e.g. by N27 nodes
+have values between 0-1023 but the actual range depends on many factors (like location of the
+sensor etc).
+
+Therefore this value can be adjusted here.
+
+Example:
+  Only turn light on if brightness sensor reports a value below 200
+  aqhome-tool setdata -N nodes/12345678/MALVALUEB -v 200
+