diff --git a/lambda/TODO b/lambda/TODO
index 1606b8c..2310783 100644
--- a/lambda/TODO
+++ b/lambda/TODO
@@ -1,6 +1,11 @@
 * C
 - What do static inline volatile extern in C do?
 - Read up on "global" variables and modules
+- Flexarray? http://en.wikipedia.org/wiki/Sizeof
+- License? (github)
+
+* AVR
+- What happens if USART data is sent to the AVR too fast (GtkTerm Send Raw File)
 
 * Functionality
 - Add rules and alerts according to FIRE RULEZ!
diff --git a/lambda/alert.c b/lambda/alert.c
index 50ce6e8..1a5740d 100644
--- a/lambda/alert.c
+++ b/lambda/alert.c
@@ -8,7 +8,6 @@
 #include <stdio.h>
 #include <stdbool.h>
 #include <avr/io.h>
-#include "USART.h"
 #include "alert.h"
 #include "sensors.h"
 #include "display.h"
diff --git a/lambda/alert.h b/lambda/alert.h
index 85eec2b..b9a6203 100644
--- a/lambda/alert.h
+++ b/lambda/alert.h
@@ -10,12 +10,26 @@
 
 void oscillateBeep(void);
 
+/**
+ * Beeps the given number of beeps with the given length. Returns quickly so
+ * it can be called from an ISR.
+ */
 void beep(uint8_t beeps, uint8_t length);
 
+/**
+ * Beeps the given number of beeps with the given length and displays the
+ * given two texts on the first and second line of the display, respectively.
+ */
 void alert(uint8_t beeps, uint8_t length, char* line0, char* line1);
 
+/**
+ * Stops beeping and blocking display updates.
+ */
 void cancelAlert(void);
 
+/**
+ * Returns true if an alert is active, false otherwise.
+ */
 bool isAlertActive(void);
 
 #endif /* ALERT_H_ */
diff --git a/lambda/command.c b/lambda/command.c
index ff97dc1..4e39579 100644
--- a/lambda/command.c
+++ b/lambda/command.c
@@ -18,7 +18,15 @@
 bool simulation = false;
 bool logging = false;
 
-void command(char* data) {
+bool isSimulation(void) {
+	return simulation;
+}
+
+bool isLogging(void) {
+	return logging;
+}
+
+void runCommand(char* data) {
 	char* fields[8];
 	char* token = strtok(data, " ");
 	uint8_t index = 0;
@@ -26,6 +34,9 @@
 		fields[index++] = token;
 		token = strtok(NULL, " ");
 	}
+	for (; index < 8; index++) {
+		fields[index] = '\0';
+	}
 	if (strcmp(fields[0], "se") == 0) {
 		// simulation enable
 		simulation = true;
@@ -49,7 +60,6 @@
 	else if (strcmp(fields[0], "cm") == 0) {
 		// cycle menu
 		cycleDisplay();
-		// updateMeas(meas);
 	}
 	else if (strcmp(fields[0], "ta") == 0) {
 		// test alert
@@ -60,11 +70,3 @@
 		updateMeas(meas);
 	}
 }
-
-bool isSimulation(void) {
-	return simulation;
-}
-
-bool isLogging(void) {
-	return logging;
-}
diff --git a/lambda/command.h b/lambda/command.h
index 7807be0..02f2269 100644
--- a/lambda/command.h
+++ b/lambda/command.h
@@ -8,10 +8,19 @@
 #ifndef COMMAND_H_
 #define COMMAND_H_
 
-void command(char* data);
-
+/**
+ * Returns true if simulation mode is enabled, false otherwise.
+ */
 bool isSimulation(void);
 
+/**
+ * Returns true if logging is enabled, false otherwise.
+ */
 bool isLogging(void);
 
+/**
+ * Evaluates and runs the given command and/or data.
+ */
+void runCommand(char* data);
+
 #endif /* COMMAND_H_ */
diff --git a/lambda/display.c b/lambda/display.c
index 0b3d7eb..468c540 100644
--- a/lambda/display.c
+++ b/lambda/display.c
@@ -17,19 +17,19 @@
 #include "display.h"
 #include "alert.h"
 
-#define MAX(x, y) (((x) > (y)) ? (x) : (y))
-#define MIN(x, y) (((x) < (y)) ? (x) : (y))
-
 #define MENU_OFF 0
 #define MENU_MIN_VALUES 1
 #define MENU_MAX_VALUES 2
 
 uint8_t position = MENU_OFF;
+bool updatePending = false;
 
+measurement measLatest;
 measurement measMin = {0, 20, 0, 20, 0, 1000};
 measurement measMax = {0, 0, 0, 0, 0, 2000};
 
 void cycleDisplay(void) {
+	updatePending = true;
 	if (isAlertActive()) {
 		// button pressed during alert
 		cancelAlert();
@@ -43,9 +43,8 @@
 }
 
 void updateMeas(measurement meas) {
-	if (isAlertActive()) {
-		return;
-	}
+	measLatest = meas;
+
 	measMin.tempI = MIN(measMin.tempI, meas.tempI);
 	measMin.tempO = MIN(measMin.tempO, meas.tempO);
 	measMin.lambda = MAX(measMin.lambda, meas.lambda);
@@ -54,12 +53,28 @@
 	measMax.tempO = MAX(measMax.tempO, meas.tempO);
 	measMax.lambda = MIN(measMax.lambda, meas.lambda);
 
+	updateDisplay();
+}
+
+void updateDisplay(void) {
+	if (isAlertActive()) {
+		return;
+	}
+
 	if (position == MENU_MIN_VALUES) {
 		displayMeas(measMin, "|<");
 	} else if (position == MENU_MAX_VALUES) {
 		displayMeas(measMax, ">|");
 	} else {
-		displayMeas(meas, "  ");
+		displayMeas(measLatest, "  ");
+	}
+
+	updatePending = false;
+}
+
+void updateDisplayIfRequested() {
+	if (updatePending) {
+		updateDisplay();
 	}
 }
 
diff --git a/lambda/display.h b/lambda/display.h
index de2bb4c..231fb23 100644
--- a/lambda/display.h
+++ b/lambda/display.h
@@ -9,29 +9,41 @@
 #define DISPLAY_H_
 
 /**
- * Cycles through the "menu" (display options).
+ * Cycles through the "menu" (display options). Returns quickly so it can
+ * be called from an ISR.
  */
 void cycleDisplay(void);
 
 /**
  * Updates the measurements, tracks min and max values since last start/reset
- * and displays the selected measurement values.
+ * and updates the display.
  */
 void updateMeas(measurement);
 
 /**
- * Formats the given measurement values and prints them via USART.
+ * Updates the display with the selected measurement values.
  */
-void printMeas(measurement);
+void updateDisplay(void);
 
 /**
- * Formats the given measurement values and displays them on an 16x2 LCD.
+ * Updates the display if an update is pending.
  */
-void displayMeas(measurement, char*);
+void updateDisplayIfRequested(void);
+
+/**
+ * Formats the given measurement values and prints them via USART.
+ */
+void printMeas(measurement meas);
+
+/**
+ * Formats the given measurement values and displays them on an 16x2 LCD along
+ * with the given hint.
+ */
+void displayMeas(measurement meas, char* hint);
 
 /**
  * Displays the given two lines of text.
  */
-void displayText(char*, char*);
+void displayText(char* line0, char* line1);
 
 #endif /* DISPLAY_H_ */
diff --git a/lambda/integers.h b/lambda/integers.h
index 42458a8..92ab527 100644
--- a/lambda/integers.h
+++ b/lambda/integers.h
@@ -12,6 +12,9 @@
 #ifndef INTEGERS_H_
 #define INTEGERS_H_
 
+#define MAX(x, y) (((x) > (y)) ? (x) : (y))
+#define MIN(x, y) (((x) < (y)) ? (x) : (y))
+
 /**
  * Divides the given numerator by the given denominator,
  * rounds to the nearest int and returns it.
diff --git a/lambda/interrupts.c b/lambda/interrupts.c
index c6627ce..3d95b15 100644
--- a/lambda/interrupts.c
+++ b/lambda/interrupts.c
@@ -51,11 +51,6 @@
 }
 
 // TODO doesn't really belong in this source file
-bool isButtonPressed(void) {
-	return buttonPressed;
-}
-
-// TODO doesn't really belong in this source file
 bool isUSARTReceived(void) {
 	return usartReceived;
 }
@@ -116,15 +111,12 @@
 	// timer clock prescaler/64 = 15.625 kHz overflowing every 16 ms
 	TCCR0B |= (1 << CS01) | (1 << CS00);
 
-	// TODO use timer2 which continues running during SLEEP_MODE_ADC?
-	// toggle pin PB1 on compare match
-	// TCCR1A |= (1 << COM1A0);
-	// CTC mode, TOP OCR1A
+	// Clear Timer on Compare Match mode, TOP OCR1A
 	TCCR1B |= (1 << WGM12);
 	// timer clock prescaler/8
 	TCCR1B |= (1 << CS11);
 	// toggles PB1 at 7.8 kHz generating a 3.9 kHz beep
 	// OCR1A = 16;
-	// less noisy 1.8 kHz
+	// 1.8 kHz is less noisy on the small piezo beeper
 	OCR1A = 32;
 }
diff --git a/lambda/interrupts.h b/lambda/interrupts.h
index 4fafbbf..254e39b 100644
--- a/lambda/interrupts.h
+++ b/lambda/interrupts.h
@@ -8,12 +8,21 @@
 #ifndef INTERRUPTS_H_
 #define INTERRUPTS_H_
 
-bool isButtonPressed(void);
-
+/**
+ * Returns true if a CR or LF terminated line of data was received via USART.
+ */
 bool isUSARTReceived(void);
 
-void getUSARTData(char*, uint8_t);
+/**
+ * Appends the data received via USART to the given string with the given
+ * length.
+ */
+void getUSARTData(char* data, uint8_t length);
 
+/**
+ * Returns true if the current timer interrupt count is equal or greater to
+ * the given count and resets it if the given boolean is true.
+ */
 bool hasIntCount(uint8_t count, bool reset);
 
 /**
diff --git a/lambda/lambda.c b/lambda/lambda.c
index 78f3e68..9ad7a58 100644
--- a/lambda/lambda.c
+++ b/lambda/lambda.c
@@ -32,8 +32,8 @@
 #include "command.h"
 
 /**
- * Does initialization and measures, displays and logs the measurements
- * infinitely.
+ * Does initialization, measures, displays and logs the measurements and
+ * runs commands sent via USART.
  */
 int main(void) {
 	initUSART();
@@ -57,15 +57,12 @@
 			}
 			updateMeas(meas);
 		}
-		if (isButtonPressed()) {
-			// update display immediately
-			updateMeas(meas);
-		}
 		if (isUSARTReceived()) {
 			char data[64];
 			getUSARTData(data, sizeof(data));
-			command(data);
+			runCommand(data);
 		}
+		updateDisplayIfRequested();
 	}
 
 	// never reached