diff --git a/lambda-test/Makefile b/lambda-test/Makefile
index 1fc122f..8c8a4da 100644
--- a/lambda-test/Makefile
+++ b/lambda-test/Makefile
@@ -1,17 +1,17 @@
+# Makefile adopted from the book Make: AVR Programming by Elliot Williams
+# https://github.com/hexagon5un/AVR-Programming
 
-##########------------------------------------------------------##########
-##########              Project-specific Details                ##########
-##########    Check these every time you start a new project    ##########
-##########------------------------------------------------------##########
-
-MCU   = atmega328p
+MCU = atmega328p
 F_CPU = 1000000
+# Also try BAUD = 19200 or 38400 if you're feeling lucky.
 BAUD = 9600
-## Also try BAUD = 19200 or 38400 if you're feeling lucky.
 
-## This is where your main() routine lives 
+# Main function
 MAIN = lambda-test.c
 
+# en: 0 (default), de: 1
+LANG = 0
+
 ## If you've split your program into multiple .c / .h files, 
 ## include the additional source (in same directory) here 
 LOCAL_SOURCE = avrjunit.c adc-test.c alert-test.c command-test.c \
diff --git a/lambda/Makefile b/lambda/Makefile
index 69df61a..4dd53cb 100644
--- a/lambda/Makefile
+++ b/lambda/Makefile
@@ -1,26 +1,21 @@
+# Makefile adopted from the book Make: AVR Programming by Elliot Williams
+# https://github.com/hexagon5un/AVR-Programming
 
-##########------------------------------------------------------##########
-##########              Project-specific Details                ##########
-##########    Check these every time you start a new project    ##########
-##########------------------------------------------------------##########
-
-MCU   = atmega328p
+MCU = atmega328p
+# Currently supported are 1 MHz and 8 MHz
 F_CPU = 1000000
+# Also try BAUD = 19200 or 38400 if you're feeling lucky.
 BAUD = 9600
-## Also try BAUD = 19200 or 38400 if you're feeling lucky.
 
-## This is where your main() routine lives 
+# Main function
 MAIN = lambda.c
 
-## en: 0 (default), de: 1
+# en: 0 (default), de: 1
 LANG = 0
 
-## If you've split your program into multiple .c / .h files, 
-## include the additional source (in same directory) here 
 LOCAL_SOURCE = usart.c interrupts.c adc.c sensors.c integers.c lcdroutines.c \
 display.c alert.c command.c strings.c rules.c
 
-## Here you can link to one more directory (and multiple .c files)
 EXTRA_SOURCE_DIR = 
 EXTRA_SOURCE_FILES = 
 
diff --git a/lambda/TODO b/lambda/TODO
index 9594df8..3b5a2e1 100644
--- a/lambda/TODO
+++ b/lambda/TODO
@@ -3,9 +3,9 @@
 - Flexarray? http://en.wikipedia.org/wiki/Sizeof
 
 * AVR
-- Take in account F_CPU everywhere CPU speed matters
 
 * Functionality
+- Handle firing up again without reset
   
 * Circuit
 - AVCC should be connected to VCC via an LC network
@@ -13,6 +13,6 @@
 * Release/put in Makefile?
 - Makefile: LANG = 0
 - pins.h LCD pins
-- interrupts.h: INTS_PER_SEC 61
-- sensors.h: SHUNT_MILLIOHMS 100
+- interrupts.h TIMER0_COMP_MATCH 122/244 (124/248)
+- sensors.h: SHUNT_MILLIOHMS 100 (111)
 - rules.c: heaterTimeout(): getTime() >= 10800
\ No newline at end of file
diff --git a/lambda/rules.c b/lambda/rules.c
index c083b08..2219a83 100644
--- a/lambda/rules.c
+++ b/lambda/rules.c
@@ -22,6 +22,7 @@
 
 static Measurement rulesMeasMax = {0, 0, 2000, 0};
 static Measurement rulesMeasPrev = {0, 0, 2000, 0};
+static bool measPrevInit = false;
 
 int8_t getDir(void) {
 	return dir;
@@ -164,6 +165,8 @@
 }
 
 // TODO what if fired up again without reset?
+// - Rules are in state fired (no reset) and don't fire again
+// - Heating is not switched on again if already switched off
 
 /**
  * Rules applied to every nth averaged measurement
@@ -206,6 +209,12 @@
 
 	age++;
 
+	// init previous measurements with current measurements
+	if (! measPrevInit) {
+		rulesMeasPrev = meas;
+		measPrevInit = true;
+	}
+
 	// try to figure out if the fire is building up or burning down by
 	// comparing current measurements with ones that are 3 minutes old.
 	if (age >= 180) {
@@ -226,11 +235,7 @@
 }
 
 void resetRules(void) {
-	rulesMeasPrev.tempI = 0;
-	rulesMeasPrev.tempO = 0;
-	rulesMeasPrev.lambda = 2000;
-	rulesMeasPrev.current = 0;
-
+	measPrevInit = false;
 	rulesMeasMax.tempI = 0;
 
 	age = 0;