diff --git a/labs/README b/labs/README
new file mode 100644
index 0000000..12d3b56
--- /dev/null
+++ b/labs/README
@@ -0,0 +1,20 @@
+Lab1 programs
+lab1-ex1   Flash LED by writing to port registers
+lab1-ex2   Flash LED, using helper functions to write to port registers directly
+lab1-ex3   Flash LED, using helper functions in module led1.c to write to port registers directly
+lab1-ex4   Flash LED, using helper functions in module led1.c to write to port registers using pio abstraction
+lab1-ex5   Flash LED, using led device driver
+
+Lab2 programs
+lab2-ex1   Implement paced loop by writing to timer/counter1 registers directly
+lab2-ex2   Implement paced loop, using helper functions in mypacer.c by writing to timer/counter1 registers directly
+lab2-ex3   Implement paced loop using pacer.c
+lab2-ex4   Flash LED in LED matrix
+lab2-ex5   Output pattern by multiplexing LED matrix
+
+Lab3 programs
+lab3-ex1   Reimplement stopwatch program using paced loop.
+lab3-ex2   Hello world!
+lab3-ex3   Using the navswitch
+lab3-ex4   Using the navswitch and IR communications.
+
diff --git a/labs/lab1-ex1/Makefile b/labs/lab1-ex1/Makefile
new file mode 100644
index 0000000..29871c7
--- /dev/null
+++ b/labs/lab1-ex1/Makefile
@@ -0,0 +1,45 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab1-ex1
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I../../drivers/avr
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab1-ex1.out
+
+
+# Compile: create object files from C source files.
+lab1-ex1.o: lab1-ex1.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab1-ex1.out: lab1-ex1.o system.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab1-ex1.out
+	$(OBJCOPY) -O ihex lab1-ex1.out lab1-ex1.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab1-ex1.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab1-ex1/doc/Makefile b/labs/lab1-ex1/doc/Makefile
new file mode 100644
index 0000000..a56a688
--- /dev/null
+++ b/labs/lab1-ex1/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex1 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab1-ex1/doc/README b/labs/lab1-ex1/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab1-ex1/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab1-ex1/lab1-ex1.c b/labs/lab1-ex1/lab1-ex1.c
new file mode 100644
index 0000000..0b42015
--- /dev/null
+++ b/labs/lab1-ex1/lab1-ex1.c
@@ -0,0 +1,20 @@
+#include <avr/io.h>
+#include "system.h"
+
+int main (void)
+{
+    system_init ();
+
+    /* Initialise port to drive LED 1.  */
+    
+    /* TODO.  */
+
+    while (1)
+    {
+
+        /* Turn LED 1 on.  */
+
+        /* TODO.  */
+
+    }
+}
diff --git a/labs/lab1-ex2/Makefile b/labs/lab1-ex2/Makefile
new file mode 100644
index 0000000..26501df
--- /dev/null
+++ b/labs/lab1-ex2/Makefile
@@ -0,0 +1,45 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab1-ex2
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I../../drivers/avr
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab1-ex2.out
+
+
+# Compile: create object files from C source files.
+lab1-ex2.o: lab1-ex2.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab1-ex2.out: lab1-ex2.o system.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab1-ex2.out
+	$(OBJCOPY) -O ihex lab1-ex2.out lab1-ex2.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab1-ex2.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab1-ex2/doc/Makefile b/labs/lab1-ex2/doc/Makefile
new file mode 100644
index 0000000..374146d
--- /dev/null
+++ b/labs/lab1-ex2/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex2 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab1-ex2/doc/README b/labs/lab1-ex2/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab1-ex2/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab1-ex2/lab1-ex2.c b/labs/lab1-ex2/lab1-ex2.c
new file mode 100644
index 0000000..99e0b45
--- /dev/null
+++ b/labs/lab1-ex2/lab1-ex2.c
@@ -0,0 +1,64 @@
+#include <avr/io.h>
+#include "system.h"
+
+
+static void led_init (void)
+{
+    /* Initialise port to drive LED 1.  */
+
+    /* TODO.  */
+}
+
+
+static void led_on (void)
+{
+    /* Set port to turn LED 1 on.  */
+
+    /* TODO.  */
+}
+
+
+static void led_off (void)
+{
+    /* Set port to turn LED 1 off.  */
+
+    /* TODO.  */
+}
+
+
+
+static void button_init (void)
+{
+    /* Initialise port to read button 1.  */
+
+    /* TODO.  */
+}
+
+
+static int button_pressed_p (void)
+{
+    /* Return non-zero if button pressed_p.  */
+
+    /* TODO.  */
+}
+
+
+int main (void)
+{
+    system_init ();
+
+    led_init ();
+    button_init ();
+
+    while (1)
+    {
+        if (button_pressed_p ())
+        {
+            led_on ();
+        }
+        else
+        {
+            led_off ();
+        }
+    }
+}
diff --git a/labs/lab1-ex3/Makefile b/labs/lab1-ex3/Makefile
new file mode 100644
index 0000000..508cf00
--- /dev/null
+++ b/labs/lab1-ex3/Makefile
@@ -0,0 +1,51 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab1-ex3
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I. -I../../drivers/avr
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab1-ex3.out
+
+
+# Compile: create object files from C source files.
+lab1-ex3.o: lab1-ex3.c ../../drivers/avr/system.h button.h led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+button.o: button.c button.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+led.o: led.c led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab1-ex3.out: lab1-ex3.o system.o button.o led.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab1-ex3.out
+	$(OBJCOPY) -O ihex lab1-ex3.out lab1-ex3.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab1-ex3.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab1-ex3/Makefile.test b/labs/lab1-ex3/Makefile.test
new file mode 100644
index 0000000..a06f0e9
--- /dev/null
+++ b/labs/lab1-ex3/Makefile.test
@@ -0,0 +1,46 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for lab1-lab1-ex3
+
+CC = gcc
+CFLAGS = -Wall -Wstrict-prototypes -Wlab1-extra -g -I. -I../../drivers/test
+
+DEL = rm
+
+
+# Default target.
+all: lab1-lab1-ex3
+
+
+# Compile: create object files from C source files.
+lab1-lab1-ex3-test.o: lab1-lab1-ex3.c ../../drivers/test/system.h io.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+mgetkey-test.o: ../../drivers/test/mgetkey.c ../../drivers/test/mgetkey.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio-test.o: ../../drivers/test/pio.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system-test.o: ../../drivers/test/system.c ../../drivers/test/avrtest.h ../../drivers/test/mgetkey.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+io-test.o: io.c io.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+
+# Link: create lab1-executable file from object files.
+lab1-lab1-ex3: lab1-lab1-ex3-test.o mgetkey-test.o pio-test.o system-test.o io-test.o
+	$(CC) $(CFLAGS) $^ -o $@ -lrt
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) lab1-lab1-ex3 lab1-lab1-ex3-test.o mgetkey-test.o pio-test.o system-test.o io-test.o
+
+
+
diff --git a/labs/lab1-ex3/button.c b/labs/lab1-ex3/button.c
new file mode 100644
index 0000000..6dfa2c4
--- /dev/null
+++ b/labs/lab1-ex3/button.c
@@ -0,0 +1,17 @@
+#include <avr/io.h>
+#include "button.h"
+
+
+/** Return non-zero if button pressed.  */
+int button_pressed_p (void)
+{
+    /* TODO.  */
+}
+
+
+/** Initialise button1.  */
+void button_init (void)
+{
+    /* TODO.  */
+}
+
diff --git a/labs/lab1-ex3/button.h b/labs/lab1-ex3/button.h
new file mode 100644
index 0000000..3069454
--- /dev/null
+++ b/labs/lab1-ex3/button.h
@@ -0,0 +1,11 @@
+#ifndef BUTTON_H
+#define BUTTON_H
+
+
+/** Return non-zero if button pressed.  */
+int button_pressed_p (void);
+
+
+/** Initialise button1.  */
+void button_init (void);
+#endif
diff --git a/labs/lab1-ex3/doc/Makefile b/labs/lab1-ex3/doc/Makefile
new file mode 100644
index 0000000..44da50e
--- /dev/null
+++ b/labs/lab1-ex3/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex3 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab1-ex3/doc/README b/labs/lab1-ex3/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab1-ex3/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab1-ex3/lab1-ex3.c b/labs/lab1-ex3/lab1-ex3.c
new file mode 100644
index 0000000..a23916f
--- /dev/null
+++ b/labs/lab1-ex3/lab1-ex3.c
@@ -0,0 +1,24 @@
+#include "button.h"
+#include "led.h"
+#include "system.h"
+
+
+int main (void)
+{
+    system_init ();
+
+    led_init ();
+    button_init ();
+
+    while (1)
+    {
+        if (button_pressed_p ())
+        {
+            led_on ();
+        }
+        else
+        {
+            led_off ();
+        }
+    }
+}
diff --git a/labs/lab1-ex3/led.c b/labs/lab1-ex3/led.c
new file mode 100644
index 0000000..726c733
--- /dev/null
+++ b/labs/lab1-ex3/led.c
@@ -0,0 +1,23 @@
+#include <avr/io.h>
+#include "led.h"
+
+
+/** Turn LED1 on.  */
+void led_on (void)
+{
+    /* TODO!  */
+}
+
+
+/** Turn LED1 off.  */
+void led_off (void)
+{
+    /* TODO!  */
+}
+
+
+/** Initialise LED1.  */
+void led_init (void)
+{
+    /* TODO!  */
+}
diff --git a/labs/lab1-ex3/led.h b/labs/lab1-ex3/led.h
new file mode 100644
index 0000000..7f1c039
--- /dev/null
+++ b/labs/lab1-ex3/led.h
@@ -0,0 +1,14 @@
+#ifndef LED_H
+#define LED_H
+
+/** Turn LED1 on.  */
+void led_on (void);
+
+
+/** Turn LED1 off.  */
+void led_off (void);
+
+
+/** Initialise LED1.  */
+void led_init (void);
+#endif
diff --git a/labs/lab1-ex4/Makefile b/labs/lab1-ex4/Makefile
new file mode 100644
index 0000000..ecde80e
--- /dev/null
+++ b/labs/lab1-ex4/Makefile
@@ -0,0 +1,54 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab1-ex4
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I. -I../../drivers/avr
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab1-ex4.out
+
+
+# Compile: create object files from C source files.
+lab1-ex4.o: lab1-ex4.c ../../drivers/avr/system.h button.h led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+button.o: button.c ../../drivers/avr/pio.h ../../drivers/avr/system.h button.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+led.o: led.c ../../drivers/avr/pio.h ../../drivers/avr/system.h led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab1-ex4.out: lab1-ex4.o pio.o system.o button.o led.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab1-ex4.out
+	$(OBJCOPY) -O ihex lab1-ex4.out lab1-ex4.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab1-ex4.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab1-ex4/Makefile.test b/labs/lab1-ex4/Makefile.test
new file mode 100644
index 0000000..eefa511
--- /dev/null
+++ b/labs/lab1-ex4/Makefile.test
@@ -0,0 +1,49 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for lab1-ex4
+
+CC = gcc
+CFLAGS = -Wall -Wstrict-prototypes -Wlab1-extra -g -I. -I../../drivers/test
+
+DEL = rm
+
+
+# Default target.
+all: lab1-ex4
+
+
+# Compile: create object files from C source files.
+lab1-ex4-test.o: lab1-ex4.c ../../drivers/test/system.h button.h led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+mgetkey-test.o: ../../drivers/test/mgetkey.c ../../drivers/test/mgetkey.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio-test.o: ../../drivers/test/pio.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system-test.o: ../../drivers/test/system.c ../../drivers/test/avrtest.h ../../drivers/test/mgetkey.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+button-test.o: button.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h button.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+led-test.o: led.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+
+# Link: create lab1-executable file from object files.
+lab1-ex4: lab1-ex4-test.o mgetkey-test.o pio-test.o system-test.o button-test.o led-test.o
+	$(CC) $(CFLAGS) $^ -o $@ -lrt
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) lab1-ex4 lab1-ex4-test.o mgetkey-test.o pio-test.o system-test.o button-test.o led-test.o
+
+
+
diff --git a/labs/lab1-ex4/button.c b/labs/lab1-ex4/button.c
new file mode 100644
index 0000000..24402db
--- /dev/null
+++ b/labs/lab1-ex4/button.c
@@ -0,0 +1,16 @@
+#include "pio.h"
+#include "button.h"
+
+/** Return non-zero if button pressed.  */
+int button_pressed_p (void)
+{
+    /* TODO.  */
+}
+
+
+/** Initialise button1.  */
+void button_init (void)
+{
+    /* TODO.  */
+}
+
diff --git a/labs/lab1-ex4/button.h b/labs/lab1-ex4/button.h
new file mode 100644
index 0000000..3069454
--- /dev/null
+++ b/labs/lab1-ex4/button.h
@@ -0,0 +1,11 @@
+#ifndef BUTTON_H
+#define BUTTON_H
+
+
+/** Return non-zero if button pressed.  */
+int button_pressed_p (void);
+
+
+/** Initialise button1.  */
+void button_init (void);
+#endif
diff --git a/labs/lab1-ex4/doc/Makefile b/labs/lab1-ex4/doc/Makefile
new file mode 100644
index 0000000..6d37994
--- /dev/null
+++ b/labs/lab1-ex4/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex4 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab1-ex4/doc/README b/labs/lab1-ex4/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab1-ex4/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab1-ex4/lab1-ex4.c b/labs/lab1-ex4/lab1-ex4.c
new file mode 100644
index 0000000..a23916f
--- /dev/null
+++ b/labs/lab1-ex4/lab1-ex4.c
@@ -0,0 +1,24 @@
+#include "button.h"
+#include "led.h"
+#include "system.h"
+
+
+int main (void)
+{
+    system_init ();
+
+    led_init ();
+    button_init ();
+
+    while (1)
+    {
+        if (button_pressed_p ())
+        {
+            led_on ();
+        }
+        else
+        {
+            led_off ();
+        }
+    }
+}
diff --git a/labs/lab1-ex4/led.c b/labs/lab1-ex4/led.c
new file mode 100644
index 0000000..d73f944
--- /dev/null
+++ b/labs/lab1-ex4/led.c
@@ -0,0 +1,23 @@
+#include "pio.h"
+#include "led.h"
+
+
+/** Turn LED1 on.  */
+void led_on (void)
+{
+    /* TODO!  */
+}
+
+
+/** Turn LED1 off.  */
+void led_off (void)
+{
+    /* TODO!  */
+}
+
+
+/** Initialise LED1.  */
+void led_init (void)
+{
+    /* TODO!  */
+}
diff --git a/labs/lab1-ex4/led.h b/labs/lab1-ex4/led.h
new file mode 100644
index 0000000..7f1c039
--- /dev/null
+++ b/labs/lab1-ex4/led.h
@@ -0,0 +1,14 @@
+#ifndef LED_H
+#define LED_H
+
+/** Turn LED1 on.  */
+void led_on (void);
+
+
+/** Turn LED1 off.  */
+void led_off (void);
+
+
+/** Initialise LED1.  */
+void led_init (void);
+#endif
diff --git a/labs/lab1-ex5/Makefile b/labs/lab1-ex5/Makefile
new file mode 100644
index 0000000..d2fc475
--- /dev/null
+++ b/labs/lab1-ex5/Makefile
@@ -0,0 +1,48 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab1-ex5
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I../../drivers/avr
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab1-ex5.out
+
+
+# Compile: create object files from C source files.
+lab1-ex5.o: lab1-ex5.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab1-ex5.out: lab1-ex5.o pio.o system.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab1-ex5.out
+	$(OBJCOPY) -O ihex lab1-ex5.out lab1-ex5.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab1-ex5.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab1-ex5/Makefile.test b/labs/lab1-ex5/Makefile.test
new file mode 100644
index 0000000..c291043
--- /dev/null
+++ b/labs/lab1-ex5/Makefile.test
@@ -0,0 +1,43 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for lab1-ex5
+
+CC = gcc
+CFLAGS = -Wall -Wstrict-prototypes -Wlab1-extra -g -I../../drivers/test
+
+DEL = rm
+
+
+# Default target.
+all: lab1-ex5
+
+
+# Compile: create object files from C source files.
+lab1-ex5-test.o: lab1-ex5.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+mgetkey-test.o: ../../drivers/test/mgetkey.c ../../drivers/test/mgetkey.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio-test.o: ../../drivers/test/pio.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system-test.o: ../../drivers/test/system.c ../../drivers/test/avrtest.h ../../drivers/test/mgetkey.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+
+# Link: create lab1-executable file from object files.
+lab1-ex5: lab1-ex5-test.o mgetkey-test.o pio-test.o system-test.o
+	$(CC) $(CFLAGS) $^ -o $@ -lrt
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) lab1-ex5 lab1-ex5-test.o mgetkey-test.o pio-test.o system-test.o
+
+
+
diff --git a/labs/lab1-ex5/doc/Makefile b/labs/lab1-ex5/doc/Makefile
new file mode 100644
index 0000000..2a6c678
--- /dev/null
+++ b/labs/lab1-ex5/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex5 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab1-ex5/doc/README b/labs/lab1-ex5/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab1-ex5/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab1-ex5/lab1-ex5.c b/labs/lab1-ex5/lab1-ex5.c
new file mode 100644
index 0000000..f02333f
--- /dev/null
+++ b/labs/lab1-ex5/lab1-ex5.c
@@ -0,0 +1,16 @@
+#include "pio.h"
+#include "system.h"
+
+
+int main (void)
+{
+    system_init ();
+
+    while (1)
+    {
+
+        /* TODO.  Use PIO module to turn on LEDs in
+           LED matrix.  */
+
+    }
+}
diff --git a/labs/lab2-ex1/Makefile b/labs/lab2-ex1/Makefile
new file mode 100644
index 0000000..3cf340a
--- /dev/null
+++ b/labs/lab2-ex1/Makefile
@@ -0,0 +1,51 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab2-ex1
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I../../drivers/avr -I../../drivers
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab2-ex1.out
+
+
+# Compile: create object files from C source files.
+lab2-ex1.o: lab2-ex1.c ../../drivers/avr/system.h ../../drivers/led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+led.o: ../../drivers/led.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab2-ex1.out: lab2-ex1.o pio.o system.o led.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab2-ex1.out
+	$(OBJCOPY) -O ihex lab2-ex1.out lab2-ex1.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab2-ex1.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab2-ex1/doc/Makefile b/labs/lab2-ex1/doc/Makefile
new file mode 100644
index 0000000..a56a688
--- /dev/null
+++ b/labs/lab2-ex1/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex1 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab2-ex1/doc/README b/labs/lab2-ex1/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab2-ex1/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab2-ex1/lab2-ex1.c b/labs/lab2-ex1/lab2-ex1.c
new file mode 100644
index 0000000..30ff88f
--- /dev/null
+++ b/labs/lab2-ex1/lab2-ex1.c
@@ -0,0 +1,28 @@
+#include <avr/io.h>
+#include "system.h"
+#include "led.h"
+
+
+int main (void)
+{
+    system_init ();
+    led_init ();
+    
+    /* TODO: Initialise timer/counter1.  */
+    
+    while (1)
+    {
+        
+        /* Turn LED on.  */
+        led_set (LED1, 1);
+        
+        /* TODO: wait for 500 milliseconds.  */
+        
+        /* Turn LED off.  */
+        led_set (LED1, 0);
+        
+        /* TODO: wait for 500 milliseconds.  */
+        
+    }
+    
+}
diff --git a/labs/lab2-ex2/Makefile b/labs/lab2-ex2/Makefile
new file mode 100644
index 0000000..d69a5bf
--- /dev/null
+++ b/labs/lab2-ex2/Makefile
@@ -0,0 +1,54 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab2-ex2
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I. -I../../drivers/avr -I../../drivers
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab2-ex2.out
+
+
+# Compile: create object files from C source files.
+lab2-ex2.o: lab2-ex2.c ../../drivers/avr/system.h ../../drivers/led.h timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+led.o: ../../drivers/led.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer.o: timer.c ../../drivers/avr/system.h timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab2-ex2.out: lab2-ex2.o pio.o system.o led.o timer.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab2-ex2.out
+	$(OBJCOPY) -O ihex lab2-ex2.out lab2-ex2.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab2-ex2.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab2-ex2/doc/Makefile b/labs/lab2-ex2/doc/Makefile
new file mode 100644
index 0000000..374146d
--- /dev/null
+++ b/labs/lab2-ex2/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex2 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab2-ex2/doc/README b/labs/lab2-ex2/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab2-ex2/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab2-ex2/lab2-ex2.c b/labs/lab2-ex2/lab2-ex2.c
new file mode 100644
index 0000000..8d23148
--- /dev/null
+++ b/labs/lab2-ex2/lab2-ex2.c
@@ -0,0 +1,28 @@
+#include "system.h"
+#include "led.h"
+
+#include "timer.h"
+
+int main (void)
+{
+    system_init ();
+    led_init ();
+    
+    /* Initialise timer.  */
+    timer_init ();
+    
+    while (1)
+    {
+        /* Turn LED on.  */
+        led_set (LED1, 1);      
+        
+        /* Wait 500ms.  */
+        timer_delay_ms (500);
+        
+        /* Turn LED off.  */
+        led_set (LED1, 0);
+        
+        /* Wait 500ms.  */
+        timer_delay_ms (500);      
+    }
+}
diff --git a/labs/lab2-ex2/timer.c b/labs/lab2-ex2/timer.c
new file mode 100644
index 0000000..6e776e3
--- /dev/null
+++ b/labs/lab2-ex2/timer.c
@@ -0,0 +1,19 @@
+#include <avr/io.h>
+#include "timer.h"
+
+/* Initialise timer.  */
+void timer_init (void)
+{
+    /* TODO */
+}
+
+
+/* Wait for the specified length of time.  */
+void timer_delay_ms (uint16_t milliseconds)
+{
+    /* TODO: Calculate the timer/counter value needed 
+       for the given number of milliseconds. */
+    
+    /* TODO: Wait for the timer/couter to reach the 
+       value calculated above.  */
+}
diff --git a/labs/lab2-ex2/timer.h b/labs/lab2-ex2/timer.h
new file mode 100644
index 0000000..80d70f2
--- /dev/null
+++ b/labs/lab2-ex2/timer.h
@@ -0,0 +1,13 @@
+#ifndef TIMER_H
+#define TIMER_H
+
+#include "system.h"
+
+/* Initialise timer.  */
+void timer_init (void);
+
+
+/* Wait for the specified length of time.  */
+void timer_delay_ms (uint16_t milliseconds);
+
+#endif
diff --git a/labs/lab2-ex3/Makefile b/labs/lab2-ex3/Makefile
new file mode 100644
index 0000000..1e5ccdd
--- /dev/null
+++ b/labs/lab2-ex3/Makefile
@@ -0,0 +1,54 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab2-ex3
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I. -I../../drivers/avr -I../../drivers
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab2-ex3.out
+
+
+# Compile: create object files from C source files.
+lab2-ex3.o: lab2-ex3.c ../../drivers/avr/system.h ../../drivers/led.h pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+led.o: ../../drivers/led.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer.o: pacer.c ../../drivers/avr/system.h pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab2-ex3.out: lab2-ex3.o pio.o system.o led.o pacer.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab2-ex3.out
+	$(OBJCOPY) -O ihex lab2-ex3.out lab2-ex3.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab2-ex3.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab2-ex3/doc/Makefile b/labs/lab2-ex3/doc/Makefile
new file mode 100644
index 0000000..44da50e
--- /dev/null
+++ b/labs/lab2-ex3/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex3 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab2-ex3/doc/README b/labs/lab2-ex3/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab2-ex3/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab2-ex3/lab2-ex3.c b/labs/lab2-ex3/lab2-ex3.c
new file mode 100644
index 0000000..2d247dd
--- /dev/null
+++ b/labs/lab2-ex3/lab2-ex3.c
@@ -0,0 +1,25 @@
+#include "system.h"
+#include "led.h"
+#include "pacer.h"
+
+
+int main (void)
+{
+    uint8_t state = 0;
+
+    system_init ();
+    led_init ();
+    
+    /* Set up pacer with a frequency of 2 Hz.  */
+    pacer_init (2);
+    
+    while (1)
+    {
+        /* Pace the loop.  */
+        pacer_wait ();
+        
+        /* Toggle LED. */
+        led_set  (LED1, state);
+        state = !state;
+    }
+}
diff --git a/labs/lab2-ex3/pacer.c b/labs/lab2-ex3/pacer.c
new file mode 100644
index 0000000..615e626
--- /dev/null
+++ b/labs/lab2-ex3/pacer.c
@@ -0,0 +1,22 @@
+#include <avr/io.h>
+#include "pacer.h"
+
+static uint16_t pacer_period;
+
+/* Initialise the pacer module.  */
+void pacer_init (uint16_t pacer_frequency)
+{
+    /* TODO: initialise timer/counter peripheral the
+       same way as in lab2/lab2-ex2/timer.c but also calculate 
+       the timer/counter value from the pacer frequency */
+}
+
+
+/* Pace a while loop.  */
+void pacer_wait (void)
+{
+
+    /* TODO: Implement the same way as the timer_delay () function 
+       lab2-except reset TCNT1 after the while loop. */
+
+}
diff --git a/labs/lab2-ex3/pacer.h b/labs/lab2-ex3/pacer.h
new file mode 100644
index 0000000..3bb1cf0
--- /dev/null
+++ b/labs/lab2-ex3/pacer.h
@@ -0,0 +1,13 @@
+#ifndef PACER_H
+#define PACER_H
+
+#include "system.h"
+
+/* Initialise the pacer module.  */
+void pacer_init (uint16_t pacer_frequency);
+
+
+/* Pace a while loop.  */
+void pacer_wait (void);
+
+#endif //PACER_H
diff --git a/labs/lab2-ex4/Makefile b/labs/lab2-ex4/Makefile
new file mode 100644
index 0000000..97278fc
--- /dev/null
+++ b/labs/lab2-ex4/Makefile
@@ -0,0 +1,51 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab2-ex4
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I. -I../../drivers/avr
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab2-ex4.out
+
+
+# Compile: create object files from C source files.
+lab2-ex4.o: lab2-ex4.c ../../drivers/avr/pio.h ../../drivers/avr/system.h pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer.o: pacer.c ../../drivers/avr/system.h pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab2-ex4.out: lab2-ex4.o pio.o system.o pacer.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab2-ex4.out
+	$(OBJCOPY) -O ihex lab2-ex4.out lab2-ex4.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab2-ex4.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab2-ex4/doc/Makefile b/labs/lab2-ex4/doc/Makefile
new file mode 100644
index 0000000..6d37994
--- /dev/null
+++ b/labs/lab2-ex4/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex4 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab2-ex4/doc/README b/labs/lab2-ex4/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab2-ex4/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab2-ex4/lab2-ex4.c b/labs/lab2-ex4/lab2-ex4.c
new file mode 100644
index 0000000..c6a4b86
--- /dev/null
+++ b/labs/lab2-ex4/lab2-ex4.c
@@ -0,0 +1,26 @@
+#include "system.h"
+#include "pio.h"
+
+/* Include the pacer module from the previous lab.
+   You must have completed this before starting this lab2-exercise.  */
+#include "pacer.h"
+
+int main (void)
+{
+    system_init ();
+    
+    /* TODO: Initialise the pins of the LED matrix.  */
+    
+
+    /* Set up pacer with a frequency of 50 Hz.  */
+    pacer_init (50);
+
+    while (1)
+    {
+        /* Pace the loop.  */
+        pacer_wait ();
+        
+        /* TODO: Drive the LED matrix using the pio functions,
+           displaying only three corner LEDs.  */
+    }
+}
diff --git a/labs/lab2-ex4/pacer.c b/labs/lab2-ex4/pacer.c
new file mode 100644
index 0000000..615e626
--- /dev/null
+++ b/labs/lab2-ex4/pacer.c
@@ -0,0 +1,22 @@
+#include <avr/io.h>
+#include "pacer.h"
+
+static uint16_t pacer_period;
+
+/* Initialise the pacer module.  */
+void pacer_init (uint16_t pacer_frequency)
+{
+    /* TODO: initialise timer/counter peripheral the
+       same way as in lab2/lab2-ex2/timer.c but also calculate 
+       the timer/counter value from the pacer frequency */
+}
+
+
+/* Pace a while loop.  */
+void pacer_wait (void)
+{
+
+    /* TODO: Implement the same way as the timer_delay () function 
+       lab2-except reset TCNT1 after the while loop. */
+
+}
diff --git a/labs/lab2-ex4/pacer.h b/labs/lab2-ex4/pacer.h
new file mode 100644
index 0000000..3bb1cf0
--- /dev/null
+++ b/labs/lab2-ex4/pacer.h
@@ -0,0 +1,13 @@
+#ifndef PACER_H
+#define PACER_H
+
+#include "system.h"
+
+/* Initialise the pacer module.  */
+void pacer_init (uint16_t pacer_frequency);
+
+
+/* Pace a while loop.  */
+void pacer_wait (void);
+
+#endif //PACER_H
diff --git a/labs/lab2-ex5/Makefile b/labs/lab2-ex5/Makefile
new file mode 100644
index 0000000..7fc2ba5
--- /dev/null
+++ b/labs/lab2-ex5/Makefile
@@ -0,0 +1,54 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab2-ex5
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I../../drivers/avr -I../../utils
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab2-ex5.out
+
+
+# Compile: create object files from C source files.
+lab2-ex5.o: lab2-ex5.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer.o: ../../drivers/avr/timer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer.o: ../../utils/pacer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab2-ex5.out: lab2-ex5.o pio.o system.o timer.o pacer.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab2-ex5.out
+	$(OBJCOPY) -O ihex lab2-ex5.out lab2-ex5.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab2-ex5.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab2-ex5/Makefile.test b/labs/lab2-ex5/Makefile.test
new file mode 100644
index 0000000..b4a7e60
--- /dev/null
+++ b/labs/lab2-ex5/Makefile.test
@@ -0,0 +1,49 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for lab2-ex5
+
+CC = gcc
+CFLAGS = -Wall -Wstrict-prototypes -Wlab2-extra -g -I../../drivers/test -I../../utils
+
+DEL = rm
+
+
+# Default target.
+all: lab2-ex5
+
+
+# Compile: create object files from C source files.
+lab2-ex5-test.o: lab2-ex5.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+mgetkey-test.o: ../../drivers/test/mgetkey.c ../../drivers/test/mgetkey.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio-test.o: ../../drivers/test/pio.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system-test.o: ../../drivers/test/system.c ../../drivers/test/avrtest.h ../../drivers/test/mgetkey.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer-test.o: ../../drivers/test/timer.c ../../drivers/test/system.h ../../drivers/test/timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer-test.o: ../../utils/pacer.c ../../drivers/test/system.h ../../drivers/test/timer.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+
+# Link: create lab2-executable file from object files.
+lab2-ex5: lab2-ex5-test.o mgetkey-test.o pio-test.o system-test.o timer-test.o pacer-test.o
+	$(CC) $(CFLAGS) $^ -o $@ -lrt
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) lab2-ex5 lab2-ex5-test.o mgetkey-test.o pio-test.o system-test.o timer-test.o pacer-test.o
+
+
+
diff --git a/labs/lab2-ex5/doc/Makefile b/labs/lab2-ex5/doc/Makefile
new file mode 100644
index 0000000..2a6c678
--- /dev/null
+++ b/labs/lab2-ex5/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex5 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab2-ex5/doc/README b/labs/lab2-ex5/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab2-ex5/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab2-ex5/lab2-ex5.c b/labs/lab2-ex5/lab2-ex5.c
new file mode 100644
index 0000000..96309cd
--- /dev/null
+++ b/labs/lab2-ex5/lab2-ex5.c
@@ -0,0 +1,61 @@
+#include "system.h"
+#include "pio.h"
+#include "pacer.h"
+
+
+/** Define PIO pins driving LED matrix rows.  */
+static const pio_t rows[] =
+{
+    LEDMAT_ROW1_PIO, LEDMAT_ROW2_PIO, LEDMAT_ROW3_PIO, 
+    LEDMAT_ROW4_PIO, LEDMAT_ROW5_PIO, LEDMAT_ROW6_PIO,
+    LEDMAT_ROW7_PIO
+};
+
+
+/** Define PIO pins driving LED matrix columns.  */
+static const pio_t cols[] =
+{
+    LEDMAT_COL1_PIO, LEDMAT_COL2_PIO, LEDMAT_COL3_PIO,
+    LEDMAT_COL4_PIO, LEDMAT_COL5_PIO
+};
+
+
+static const uint8_t bitmap[] =
+{
+    0x30, 0x46, 0x40, 0x46, 0x30
+};
+
+
+
+static void display_column (uint8_t row_pattern, uint8_t current_column)
+{
+
+    /* TODO */
+
+}
+
+
+int main (void)
+{
+    uint8_t current_column = 0;
+  
+    system_init ();
+    pacer_init (500);
+    
+    /* TODO: Initialise LED matrix pins.  */
+    
+
+    while (1)
+    {
+        pacer_wait ();
+        
+        display_column (bitmap[current_column], current_column);
+    
+        current_column++;
+    
+        if (current_column > (LEDMAT_COLS_NUM - 1))
+        {
+            current_column = 0;
+        }           
+    }
+}
diff --git a/labs/lab3-ex1/Makefile b/labs/lab3-ex1/Makefile
new file mode 100644
index 0000000..62935b8
--- /dev/null
+++ b/labs/lab3-ex1/Makefile
@@ -0,0 +1,69 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab3-ex1
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I../../drivers -I../../fonts -I../../drivers/avr -I../../utils
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab3-ex1.out
+
+
+# Compile: create object files from C source files.
+lab3-ex1.o: lab3-ex1.c ../../drivers/avr/system.h ../../drivers/button.h ../../drivers/display.h ../../fonts/font3x5_1_r.h ../../utils/font.h ../../utils/pacer.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer.o: ../../drivers/avr/timer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+button.o: ../../drivers/button.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/button.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+display.o: ../../drivers/display.c ../../drivers/avr/system.h ../../drivers/display.h ../../drivers/ledmat.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ledmat.o: ../../drivers/ledmat.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/ledmat.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+font.o: ../../utils/font.c ../../drivers/avr/system.h ../../utils/font.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer.o: ../../utils/pacer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+tinygl.o: ../../utils/tinygl.c ../../drivers/avr/system.h ../../drivers/display.h ../../utils/font.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab3-ex1.out: lab3-ex1.o pio.o system.o timer.o button.o display.o ledmat.o font.o pacer.o tinygl.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab3-ex1.out
+	$(OBJCOPY) -O ihex lab3-ex1.out lab3-ex1.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab3-ex1.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab3-ex1/Makefile.test b/labs/lab3-ex1/Makefile.test
new file mode 100644
index 0000000..55efcb4
--- /dev/null
+++ b/labs/lab3-ex1/Makefile.test
@@ -0,0 +1,64 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for lab3-ex1
+
+CC = gcc
+CFLAGS = -Wall -Wstrict-prototypes -Wlab3-extra -g -I../../drivers/test -I../../drivers -I../../fonts -I../../utils
+
+DEL = rm
+
+
+# Default target.
+all: lab3-ex1
+
+
+# Compile: create object files from C source files.
+lab3-ex1-test.o: lab3-ex1.c ../../drivers/button.h ../../drivers/display.h ../../drivers/test/system.h ../../fonts/font3x5_1_r.h ../../utils/font.h ../../utils/pacer.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+button-test.o: ../../drivers/button.c ../../drivers/button.h ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+display-test.o: ../../drivers/display.c ../../drivers/display.h ../../drivers/ledmat.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ledmat-test.o: ../../drivers/ledmat.c ../../drivers/ledmat.h ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+mgetkey-test.o: ../../drivers/test/mgetkey.c ../../drivers/test/mgetkey.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio-test.o: ../../drivers/test/pio.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system-test.o: ../../drivers/test/system.c ../../drivers/test/avrtest.h ../../drivers/test/mgetkey.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer-test.o: ../../drivers/test/timer.c ../../drivers/test/system.h ../../drivers/test/timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+font-test.o: ../../utils/font.c ../../drivers/test/system.h ../../utils/font.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer-test.o: ../../utils/pacer.c ../../drivers/test/system.h ../../drivers/test/timer.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+tinygl-test.o: ../../utils/tinygl.c ../../drivers/display.h ../../drivers/test/system.h ../../utils/font.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+
+# Link: create lab3-executable file from object files.
+lab3-ex1: lab3-ex1-test.o button-test.o display-test.o ledmat-test.o mgetkey-test.o pio-test.o system-test.o timer-test.o font-test.o pacer-test.o tinygl-test.o
+	$(CC) $(CFLAGS) $^ -o $@ -lrt
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) lab3-ex1 lab3-ex1-test.o button-test.o display-test.o ledmat-test.o mgetkey-test.o pio-test.o system-test.o timer-test.o font-test.o pacer-test.o tinygl-test.o
+
+
+
diff --git a/labs/lab3-ex1/doc/Makefile b/labs/lab3-ex1/doc/Makefile
new file mode 100644
index 0000000..a56a688
--- /dev/null
+++ b/labs/lab3-ex1/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex1 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab3-ex1/doc/README b/labs/lab3-ex1/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab3-ex1/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab3-ex1/lab3-ex1.c b/labs/lab3-ex1/lab3-ex1.c
new file mode 100644
index 0000000..1d7f4c9
--- /dev/null
+++ b/labs/lab3-ex1/lab3-ex1.c
@@ -0,0 +1,24 @@
+#include "system.h"
+#include "button.h"
+#include "pacer.h"
+#include "tinygl.h"
+#include "../fonts/font3x5_1.h"
+
+
+int main (void)
+{
+    system_init();
+    
+    /* TODO: Initialise the button driver, tinygl, and the pacer.  */
+
+
+    while(1)
+    {
+        pacer_wait();
+
+	/* TODO: Implement the functionality of the tasks in the
+           stopwatch1 program.  */
+
+    }
+    return 0;
+}
diff --git a/labs/lab3-ex2/Makefile b/labs/lab3-ex2/Makefile
new file mode 100644
index 0000000..cf9b195
--- /dev/null
+++ b/labs/lab3-ex2/Makefile
@@ -0,0 +1,66 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab3-ex2
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I../../drivers -I../../fonts -I../../drivers/avr -I../../utils
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab3-ex2.out
+
+
+# Compile: create object files from C source files.
+lab3-ex2.o: lab3-ex2.c ../../drivers/avr/system.h ../../drivers/display.h ../../fonts/font5x7_1.h ../../utils/font.h ../../utils/pacer.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer.o: ../../drivers/avr/timer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+display.o: ../../drivers/display.c ../../drivers/avr/system.h ../../drivers/display.h ../../drivers/ledmat.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ledmat.o: ../../drivers/ledmat.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/ledmat.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+font.o: ../../utils/font.c ../../drivers/avr/system.h ../../utils/font.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer.o: ../../utils/pacer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+tinygl.o: ../../utils/tinygl.c ../../drivers/avr/system.h ../../drivers/display.h ../../utils/font.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab3-ex2.out: lab3-ex2.o pio.o system.o timer.o display.o ledmat.o font.o pacer.o tinygl.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab3-ex2.out
+	$(OBJCOPY) -O ihex lab3-ex2.out lab3-ex2.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab3-ex2.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab3-ex2/Makefile.test b/labs/lab3-ex2/Makefile.test
new file mode 100644
index 0000000..da46db7
--- /dev/null
+++ b/labs/lab3-ex2/Makefile.test
@@ -0,0 +1,61 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for lab3-ex2
+
+CC = gcc
+CFLAGS = -Wall -Wstrict-prototypes -Wlab3-extra -g -I../../drivers/test -I../../drivers -I../../fonts -I../../utils
+
+DEL = rm
+
+
+# Default target.
+all: lab3-ex2
+
+
+# Compile: create object files from C source files.
+lab3-ex2-test.o: lab3-ex2.c ../../drivers/display.h ../../drivers/test/system.h ../../fonts/font5x7_1.h ../../utils/font.h ../../utils/pacer.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+display-test.o: ../../drivers/display.c ../../drivers/display.h ../../drivers/ledmat.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ledmat-test.o: ../../drivers/ledmat.c ../../drivers/ledmat.h ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+mgetkey-test.o: ../../drivers/test/mgetkey.c ../../drivers/test/mgetkey.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio-test.o: ../../drivers/test/pio.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system-test.o: ../../drivers/test/system.c ../../drivers/test/avrtest.h ../../drivers/test/mgetkey.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer-test.o: ../../drivers/test/timer.c ../../drivers/test/system.h ../../drivers/test/timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+font-test.o: ../../utils/font.c ../../drivers/test/system.h ../../utils/font.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer-test.o: ../../utils/pacer.c ../../drivers/test/system.h ../../drivers/test/timer.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+tinygl-test.o: ../../utils/tinygl.c ../../drivers/display.h ../../drivers/test/system.h ../../utils/font.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+
+# Link: create lab3-executable file from object files.
+lab3-ex2: lab3-ex2-test.o display-test.o ledmat-test.o mgetkey-test.o pio-test.o system-test.o timer-test.o font-test.o pacer-test.o tinygl-test.o
+	$(CC) $(CFLAGS) $^ -o $@ -lrt
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) lab3-ex2 lab3-ex2-test.o display-test.o ledmat-test.o mgetkey-test.o pio-test.o system-test.o timer-test.o font-test.o pacer-test.o tinygl-test.o
+
+
+
diff --git a/labs/lab3-ex2/doc/Makefile b/labs/lab3-ex2/doc/Makefile
new file mode 100644
index 0000000..374146d
--- /dev/null
+++ b/labs/lab3-ex2/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex2 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab3-ex2/doc/README b/labs/lab3-ex2/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab3-ex2/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab3-ex2/lab3-ex2.c b/labs/lab3-ex2/lab3-ex2.c
new file mode 100644
index 0000000..ac83b83
--- /dev/null
+++ b/labs/lab3-ex2/lab3-ex2.c
@@ -0,0 +1,29 @@
+#include "system.h"
+#include "pacer.h"
+#include "tinygl.h"
+#include "../fonts/font5x7_1.h"
+
+
+#define PACER_RATE 500
+#define MESSAGE_RATE 10
+
+int main (void)
+{
+    system_init();
+
+    /* TODO: Initialise tinygl. */
+
+    /* TODO: Set the message using tinygl_tlab3-ext().  */
+    
+
+    pacer_init (PACER_RATE);
+
+    while(1)
+    {
+        pacer_wait();
+        
+        /* TODO: Call the tinygl update function. */
+        
+    }
+    return 0;
+}
diff --git a/labs/lab3-ex3/Makefile b/labs/lab3-ex3/Makefile
new file mode 100644
index 0000000..bf9a248
--- /dev/null
+++ b/labs/lab3-ex3/Makefile
@@ -0,0 +1,69 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab3-ex3
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I../../drivers -I../../fonts -I../../drivers/avr -I../../utils
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab3-ex3.out
+
+
+# Compile: create object files from C source files.
+lab3-ex3.o: lab3-ex3.c ../../drivers/avr/system.h ../../drivers/display.h ../../drivers/navswitch.h ../../fonts/font5x7_1.h ../../utils/font.h ../../utils/pacer.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer.o: ../../drivers/avr/timer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+display.o: ../../drivers/display.c ../../drivers/avr/system.h ../../drivers/display.h ../../drivers/ledmat.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ledmat.o: ../../drivers/ledmat.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/ledmat.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+navswitch.o: ../../drivers/navswitch.c ../../drivers/avr/delay.h ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/navswitch.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+font.o: ../../utils/font.c ../../drivers/avr/system.h ../../utils/font.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer.o: ../../utils/pacer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+tinygl.o: ../../utils/tinygl.c ../../drivers/avr/system.h ../../drivers/display.h ../../utils/font.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab3-ex3.out: lab3-ex3.o pio.o system.o timer.o display.o ledmat.o navswitch.o font.o pacer.o tinygl.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab3-ex3.out
+	$(OBJCOPY) -O ihex lab3-ex3.out lab3-ex3.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab3-ex3.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab3-ex3/Makefile.test b/labs/lab3-ex3/Makefile.test
new file mode 100644
index 0000000..f48c772
--- /dev/null
+++ b/labs/lab3-ex3/Makefile.test
@@ -0,0 +1,64 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for lab3-ex3
+
+CC = gcc
+CFLAGS = -Wall -Wstrict-prototypes -Wlab3-extra -g -I../../drivers/test -I../../drivers -I../../fonts -I../../utils
+
+DEL = rm
+
+
+# Default target.
+all: lab3-ex3
+
+
+# Compile: create object files from C source files.
+lab3-ex3-test.o: lab3-ex3.c ../../drivers/display.h ../../drivers/navswitch.h ../../drivers/test/system.h ../../fonts/font5x7_1.h ../../utils/font.h ../../utils/pacer.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+display-test.o: ../../drivers/display.c ../../drivers/display.h ../../drivers/ledmat.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ledmat-test.o: ../../drivers/ledmat.c ../../drivers/ledmat.h ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+navswitch-test.o: ../../drivers/navswitch.c ../../drivers/navswitch.h ../../drivers/test/avrtest.h ../../drivers/test/delay.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+mgetkey-test.o: ../../drivers/test/mgetkey.c ../../drivers/test/mgetkey.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio-test.o: ../../drivers/test/pio.c ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system-test.o: ../../drivers/test/system.c ../../drivers/test/avrtest.h ../../drivers/test/mgetkey.h ../../drivers/test/pio.h ../../drivers/test/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer-test.o: ../../drivers/test/timer.c ../../drivers/test/system.h ../../drivers/test/timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+font-test.o: ../../utils/font.c ../../drivers/test/system.h ../../utils/font.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer-test.o: ../../utils/pacer.c ../../drivers/test/system.h ../../drivers/test/timer.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+tinygl-test.o: ../../utils/tinygl.c ../../drivers/display.h ../../drivers/test/system.h ../../utils/font.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+
+# Link: create lab3-executable file from object files.
+lab3-ex3: lab3-ex3-test.o display-test.o ledmat-test.o navswitch-test.o mgetkey-test.o pio-test.o system-test.o timer-test.o font-test.o pacer-test.o tinygl-test.o
+	$(CC) $(CFLAGS) $^ -o $@ -lrt
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) lab3-ex3 lab3-ex3-test.o display-test.o ledmat-test.o navswitch-test.o mgetkey-test.o pio-test.o system-test.o timer-test.o font-test.o pacer-test.o tinygl-test.o
+
+
+
diff --git a/labs/lab3-ex3/doc/Makefile b/labs/lab3-ex3/doc/Makefile
new file mode 100644
index 0000000..44da50e
--- /dev/null
+++ b/labs/lab3-ex3/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex3 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab3-ex3/doc/README b/labs/lab3-ex3/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab3-ex3/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab3-ex3/lab3-ex3.c b/labs/lab3-ex3/lab3-ex3.c
new file mode 100644
index 0000000..9d1099c
--- /dev/null
+++ b/labs/lab3-ex3/lab3-ex3.c
@@ -0,0 +1,50 @@
+#include "system.h"
+#include "pacer.h"
+#include "navswitch.h"
+#include "tinygl.h"
+#include "../fonts/font5x7_1.h"
+
+
+#define PACER_RATE 500
+#define MESSAGE_RATE 10
+
+
+void display_character (char character)
+{
+    char buffer[2];
+
+    buffer[0] = character;
+    buffer[1] = '\0';
+    tinygl_text (buffer);
+}
+
+
+int main (void)
+{
+    char character = 'A';
+
+    system_init ();
+
+    tinygl_init (PACER_RATE);
+    tinygl_font_set (&font5x7_1);
+    tinygl_text_speed_set (MESSAGE_RATE);
+
+    /* TODO: Initialise navigation switch driver.  */
+
+    pacer_init (PACER_RATE);
+
+    while(1)
+    {
+        pacer_wait ();
+        tinygl_update ();
+        
+        /* TODO: Call the navswitch update function.  */
+        
+        /* TODO: Increment character if NORTH is pressed.  */
+        
+        /* TODO: Decrement character if SOUTH is pressed.  */
+        
+        display_character (character);
+    }
+    return 0;
+}
diff --git a/labs/lab3-ex4/Makefile b/labs/lab3-ex4/Makefile
new file mode 100644
index 0000000..625b4b7
--- /dev/null
+++ b/labs/lab3-ex4/Makefile
@@ -0,0 +1,81 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for lab3-ex4
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I../../drivers -I../../fonts -I../../drivers/avr -I../../utils
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: lab3-ex4.out
+
+
+# Compile: create object files from C source files.
+lab3-ex4.o: lab3-ex4.c ../../drivers/avr/ir_uart.h ../../drivers/avr/system.h ../../drivers/display.h ../../drivers/navswitch.h ../../fonts/font5x7_1.h ../../utils/font.h ../../utils/pacer.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ir_uart.o: ../../drivers/avr/ir_uart.c ../../drivers/avr/ir_uart.h ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/avr/timer0.h ../../drivers/avr/usart1.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+prescale.o: ../../drivers/avr/prescale.c ../../drivers/avr/prescale.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer.o: ../../drivers/avr/timer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer0.o: ../../drivers/avr/timer0.c ../../drivers/avr/bits.h ../../drivers/avr/prescale.h ../../drivers/avr/system.h ../../drivers/avr/timer0.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+usart1.o: ../../drivers/avr/usart1.c ../../drivers/avr/system.h ../../drivers/avr/usart1.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+display.o: ../../drivers/display.c ../../drivers/avr/system.h ../../drivers/display.h ../../drivers/ledmat.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ledmat.o: ../../drivers/ledmat.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/ledmat.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+navswitch.o: ../../drivers/navswitch.c ../../drivers/avr/delay.h ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/navswitch.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+font.o: ../../utils/font.c ../../drivers/avr/system.h ../../utils/font.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer.o: ../../utils/pacer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+tinygl.o: ../../utils/tinygl.c ../../drivers/avr/system.h ../../drivers/display.h ../../utils/font.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+lab3-ex4.out: lab3-ex4.o ir_uart.o pio.o prescale.o system.o timer.o timer0.o usart1.o display.o ledmat.o navswitch.o font.o pacer.o tinygl.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: lab3-ex4.out
+	$(OBJCOPY) -O ihex lab3-ex4.out lab3-ex4.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash lab3-ex4.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/lab3-ex4/Makefile.test b/labs/lab3-ex4/Makefile.test
new file mode 100644
index 0000000..e69de29
diff --git a/labs/lab3-ex4/doc/Makefile b/labs/lab3-ex4/doc/Makefile
new file mode 100644
index 0000000..6d37994
--- /dev/null
+++ b/labs/lab3-ex4/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for ex4 docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/lab3-ex4/doc/README b/labs/lab3-ex4/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/lab3-ex4/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/lab3-ex4/lab3-ex4.c b/labs/lab3-ex4/lab3-ex4.c
new file mode 100644
index 0000000..62671ca
--- /dev/null
+++ b/labs/lab3-ex4/lab3-ex4.c
@@ -0,0 +1,57 @@
+#include "system.h"
+#include "pacer.h"
+#include "navswitch.h"
+#include "ir_uart.h"
+#include "tinygl.h"
+#include "../fonts/font5x7_1.h"
+
+
+#define PACER_RATE 500
+#define MESSAGE_RATE 10
+
+
+void display_character (char character)
+{
+    char buffer[2];
+    buffer[0] = character;
+    buffer[1] = '\0';
+    tinygl_text (buffer);
+}
+
+
+int main (void)
+{
+    char character = 'A';
+
+    system_init ();
+    tinygl_init (PACER_RATE);
+    tinygl_font_set (&font5x7_1);
+    tinygl_text_speed_set (MESSAGE_RATE);
+    navswitch_init ();
+
+    /* TODO: Initialise IR driver.  */
+
+
+    pacer_init (PACER_RATE);
+
+    while (1)
+    {
+        pacer_wait ();
+        tinygl_update ();
+        navswitch_update ();
+        
+        if (navswitch_push_event_p (NAVSWITCH_NORTH))
+            character++;
+
+        if (navswitch_push_event_p (NAVSWITCH_SOUTH))
+            character--;
+
+        /* TODO: Transmit the character over IR on a NAVSWITCH_PUSH
+           event.  */
+        
+        display_character (character);
+        
+    }
+
+    return 0;
+}
diff --git a/labs/receiver/Makefile b/labs/receiver/Makefile
new file mode 100644
index 0000000..02251f0
--- /dev/null
+++ b/labs/receiver/Makefile
@@ -0,0 +1,78 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for receiver
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I../../drivers -I../../fonts -I../../drivers/avr -I../../utils
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: receiver.out
+
+
+# Compile: create object files from C source files.
+receiver.o: receiver.c ../../drivers/avr/ir_uart.h ../../drivers/avr/system.h ../../drivers/display.h ../../fonts/font5x7_1.h ../../utils/font.h ../../utils/pacer.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ir_uart.o: ../../drivers/avr/ir_uart.c ../../drivers/avr/ir_uart.h ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/avr/timer0.h ../../drivers/avr/usart1.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pio.o: ../../drivers/avr/pio.c ../../drivers/avr/pio.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+prescale.o: ../../drivers/avr/prescale.c ../../drivers/avr/prescale.h ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+system.o: ../../drivers/avr/system.c ../../drivers/avr/system.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer.o: ../../drivers/avr/timer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+timer0.o: ../../drivers/avr/timer0.c ../../drivers/avr/bits.h ../../drivers/avr/prescale.h ../../drivers/avr/system.h ../../drivers/avr/timer0.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+usart1.o: ../../drivers/avr/usart1.c ../../drivers/avr/system.h ../../drivers/avr/usart1.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+display.o: ../../drivers/display.c ../../drivers/avr/system.h ../../drivers/display.h ../../drivers/ledmat.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ledmat.o: ../../drivers/ledmat.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/ledmat.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+font.o: ../../utils/font.c ../../drivers/avr/system.h ../../utils/font.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+pacer.o: ../../utils/pacer.c ../../drivers/avr/system.h ../../drivers/avr/timer.h ../../utils/pacer.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+tinygl.o: ../../utils/tinygl.c ../../drivers/avr/system.h ../../drivers/display.h ../../utils/font.h ../../utils/tinygl.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+receiver.out: receiver.o ir_uart.o pio.o prescale.o system.o timer.o timer0.o usart1.o display.o ledmat.o font.o pacer.o tinygl.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: receiver.out
+	$(OBJCOPY) -O ihex receiver.out receiver.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash receiver.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/labs/receiver/Makefile.test b/labs/receiver/Makefile.test
new file mode 100644
index 0000000..e69de29
diff --git a/labs/receiver/doc/Makefile b/labs/receiver/doc/Makefile
new file mode 100644
index 0000000..5606cae
--- /dev/null
+++ b/labs/receiver/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for receiver docs
+
+DEL = rm
+
+all: file_dependencies.pdf module_dependencies.pdf makefile_dependencies.pdf build_dependencies.pdf callgraph.pdf
+
+file_dependencies.pdf: files.d 
+	../../../etc/graphdeps.py $< --out $@
+
+module_dependencies.pdf: modules.d 
+	../../../etc/graphdeps.py $< --modules --out $@
+
+makefile_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@
+
+build_dependencies.pdf: ../Makefile
+	../../../etc/graphdeps.py $< --out $@ --showops
+
+callgraph.pdf: callgraph.d
+	../../../etc/graphdeps.py --calls --modules $< --out $@ --showops
+
+
+files.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --files . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/files.d)
+
+
+modules.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --relpath --modules . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system > doc/modules.d)
+
+
+callgraph.d: ../Makefile
+	(cd ..;	../../etc/makemake.py --cc="avr-gcc" --cflags="-Os -mmcu=atmega32u2" --relpath --calls . . ../../drivers ../../drivers/avr ../../utils ../../extra --exclude system.h > doc/callgraph.d)
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) *.d *.pdf
+
diff --git a/labs/receiver/doc/README b/labs/receiver/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/labs/receiver/doc/README
@@ -0,0 +1,16 @@
+Running make in this directory will generate a number of PDF graphs.
+In the callgraph, the arrows means "calls".  In the dependency graphs,
+the arrows means "requires" (or "depends upon").
+
+callgraph.pdf             This shows the callgraph, i.e., what functions each
+                          function in the program calls.
+module_dependencies.pdf   This shows the dependencies between the modules.
+file_dependencies.pdf     This shows the dependencies between the files.
+makefile_dependencies.pdf This shows the dependencies required by make when
+                          building the program.
+build_dependencies.pdf    This is like makefile_dependencies.pdf but shows
+                          the operations performed to generate the new file.
+
+callgraph.d               This shows the callgraph in text format.
+files.d                   This shows the file dependencies in text format.
+modules.d                 This shows the module dependencies in text format.
diff --git a/labs/receiver/receiver.c b/labs/receiver/receiver.c
new file mode 100644
index 0000000..fdbd7f7
--- /dev/null
+++ b/labs/receiver/receiver.c
@@ -0,0 +1,43 @@
+#include "system.h"
+#include "pacer.h"
+#include "ir_uart.h"
+#include "tinygl.h"
+#include "../fonts/font5x7_1.h"
+
+
+#define PACER_RATE 500
+#define MESSAGE_RATE 10
+
+
+void display_character (char character)
+{
+    char buffer[2];
+    buffer[0] = character;
+    buffer[1] = '\0';
+    tinygl_tlab3-ext (buffer);
+}
+
+
+int main (void)
+{
+    system_init ();
+    tinygl_init (PACER_RATE);
+    tinygl_font_set (&font5x7_1);
+    tinygl_tlab3-ext_speed_set (MESSAGE_RATE);
+    ir_uart_init ();
+
+    pacer_init (PACER_RATE);
+
+    while (1)
+    {
+        pacer_wait ();      
+
+	tinygl_update ();
+
+        if (ir_uart_read_ready_p ())
+        {
+	    display_character (ir_uart_getc ());
+        }
+    }
+    return 0;
+}