diff --git a/apps/squeak2/Makefile b/apps/squeak2/Makefile
new file mode 100644
index 0000000..1cb6c69
--- /dev/null
+++ b/apps/squeak2/Makefile
@@ -0,0 +1,72 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   12 Sep 2010
+# Descr:  Makefile for squeak2
+
+# Definitions.
+CC = avr-gcc
+CFLAGS = -mmcu=atmega32u2 -Os -Wall -Wstrict-prototypes -Wextra -g -I. -I../../utils -I../../fonts -I../../drivers -I../../drivers/avr -I../../extra
+OBJCOPY = avr-objcopy
+SIZE = avr-size
+DEL = rm
+
+
+# Default target.
+all: squeak2.out
+
+
+# Compile: create object files from C source files.
+squeak2.o: squeak2.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/avr/timer.h ../../drivers/button.h ../../drivers/led.h ../../extra/mmelody.h ../../extra/squeaker.h ../../extra/ticker.h ../../extra/tweeter.h ../../utils/task.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 $@
+
+led.o: ../../drivers/led.c ../../drivers/avr/pio.h ../../drivers/avr/system.h ../../drivers/led.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+mmelody.o: ../../extra/mmelody.c ../../drivers/avr/system.h ../../extra/mmelody.h ../../extra/ticker.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+squeaker.o: ../../extra/squeaker.c ../../drivers/avr/system.h ../../extra/squeaker.h ../../extra/ticker.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ticker.o: ../../extra/ticker.c
+	$(CC) -c $(CFLAGS) $< -o $@
+
+tweeter.o: ../../extra/tweeter.c ../../drivers/avr/system.h ../../extra/ticker.h ../../extra/tweeter.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+task.o: ../../utils/task.c ../../drivers/avr/system.h ../../drivers/avr/timer.h ../../utils/task.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+# Link: create ELF output file from object files.
+squeak2.out: squeak2.o pio.o system.o timer.o button.o led.o mmelody.o squeaker.o ticker.o tweeter.o task.o
+	$(CC) $(CFLAGS) $^ -o $@ -lm
+	$(SIZE) $@
+
+
+# Target: clean project.
+.PHONY: clean
+clean: 
+	-$(DEL) *.o *.out *.hex
+
+
+# Target: program project.
+.PHONY: program
+program: squeak2.out
+	$(OBJCOPY) -O ihex squeak2.out squeak2.hex
+	dfu-programmer atmega32u2 erase; dfu-programmer atmega32u2 flash squeak2.hex; dfu-programmer atmega32u2 start
+
+
diff --git a/apps/squeak2/Makefile.test b/apps/squeak2/Makefile.test
new file mode 100644
index 0000000..9b72bb2
--- /dev/null
+++ b/apps/squeak2/Makefile.test
@@ -0,0 +1,64 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for squeak2
+
+CC = gcc
+CFLAGS = -Wall -Wstrict-prototypes -Wextra -g -I. -I../../utils -I../../drivers -I../../drivers/test -I../../extra
+
+DEL = rm
+
+
+# Default target.
+all: squeak2
+
+
+# Compile: create object files from C source files.
+squeak2-test.o: squeak2.c ../../drivers/led.h ../../drivers/test/avrtest.h ../../drivers/test/pio.h ../../drivers/test/system.h ../../drivers/test/timer.h ../../extra/mmelody.h ../../extra/squeaker.h ../../extra/ticker.h ../../extra/tweeter.h ../../utils/task.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+led-test.o: ../../drivers/led.c ../../drivers/led.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
+	$(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 $@
+
+mmelody-test.o: ../../extra/mmelody.c ../../drivers/test/system.h ../../extra/mmelody.h ../../extra/ticker.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+squeaker-test.o: ../../extra/squeaker.c ../../drivers/test/system.h ../../extra/squeaker.h ../../extra/ticker.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+ticker-test.o: ../../extra/ticker.c
+	$(CC) -c $(CFLAGS) $< -o $@
+
+tweeter-test.o: ../../extra/tweeter.c ../../drivers/test/system.h ../../extra/ticker.h ../../extra/tweeter.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+task-test.o: ../../utils/task.c ../../drivers/test/system.h ../../drivers/test/timer.h ../../utils/task.h
+	$(CC) -c $(CFLAGS) $< -o $@
+
+
+
+
+# Link: create executable file from object files.
+squeak2: squeak2-test.o led-test.o mgetkey-test.o pio-test.o system-test.o timer-test.o mmelody-test.o squeaker-test.o ticker-test.o tweeter-test.o task-test.o
+	$(CC) $(CFLAGS) $^ -o $@ -lrt
+
+
+# Clean: delete derived files.
+.PHONY: clean
+clean: 
+	-$(DEL) squeak2 squeak2-test.o led-test.o mgetkey-test.o pio-test.o system-test.o timer-test.o mmelody-test.o squeaker-test.o ticker-test.o tweeter-test.o task-test.o
+
+
+
diff --git a/apps/squeak2/doc/Makefile b/apps/squeak2/doc/Makefile
new file mode 100644
index 0000000..7713459
--- /dev/null
+++ b/apps/squeak2/doc/Makefile
@@ -0,0 +1,42 @@
+# File:   Makefile
+# Author: M. P. Hayes, UCECE
+# Date:   11 Sep 2010
+# Descr:  Makefile for squeak1 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/apps/squeak2/doc/README b/apps/squeak2/doc/README
new file mode 100644
index 0000000..39a9712
--- /dev/null
+++ b/apps/squeak2/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/apps/squeak2/holiday_in_cambodia.mmel b/apps/squeak2/holiday_in_cambodia.mmel
new file mode 100644
index 0000000..9a62d93
--- /dev/null
+++ b/apps/squeak2/holiday_in_cambodia.mmel
@@ -0,0 +1,2 @@
+/* A2, A3 */
+"@96*8C3CCA2E3D#///CCCA2F#3F///AAAA2E3D#//CCCA2F#3F///CCCB2//A#//AA"
diff --git a/apps/squeak2/mysterex.mmel b/apps/squeak2/mysterex.mmel
new file mode 100644
index 0000000..762140c
--- /dev/null
+++ b/apps/squeak2/mysterex.mmel
@@ -0,0 +1,2 @@
+/* A#2, F3 */
+"@180*8<F3FD#D#DDCCD#D#DDCCA#2A#C3/CC/C//>"
diff --git a/apps/squeak2/squeak2.c b/apps/squeak2/squeak2.c
new file mode 100644
index 0000000..45c85e0
--- /dev/null
+++ b/apps/squeak2/squeak2.c
@@ -0,0 +1,125 @@
+/** @file   squeak2.c
+    @author M.P. Hayes
+    @date   30 Aug 2011
+*/
+
+#include "system.h"
+#include "button.h"
+#include "led.h"
+#include "pio.h"
+#include "task.h"
+#include "tweeter.h"
+#include "squeaker.h"
+#include "mmelody.h"
+
+
+/* Connect piezo tweeter to outermost pins of UCFK4 P1 connector.  */
+#define PIEZO_PIO PIO_DEFINE (PORT_D, 6)
+
+/* Define polling rate in Hz.  */
+#define LED_TASK_RATE 2
+
+#define TWEETER_TASK_RATE 20000
+
+#define TUNE_TASK_RATE 100
+
+#define BUTTON_TASK_RATE 10
+
+#define TUNE_BPM_RATE 200
+
+
+static tweeter_scale_t scale_table[] = TWEETER_SCALE_TABLE (TWEETER_TASK_RATE);
+static tweeter_t tweeter;
+static mmelody_t melody;
+static mmelody_obj_t melody_info;
+static tweeter_obj_t tweeter_info;
+
+
+static const char tune1[] =
+{
+#include "mysterex.mmel"
+"    >"
+};
+
+
+static void led_flash_task_init (void)
+{
+    led_init ();
+}
+
+
+static void led_flash_task (__unused__ void *data)
+{
+    static uint8_t state = 0;
+
+    led_set (LED1, state);
+    state = !state;
+}
+
+
+static void tweeter_task_init (void)
+{
+    tweeter = tweeter_init (&tweeter_info, TWEETER_TASK_RATE, scale_table);
+
+    pio_config_set (PIEZO_PIO, PIO_OUTPUT_LOW);
+}
+
+
+static void tweeter_task (__unused__ void *data)
+{
+    pio_output_set (PIEZO_PIO, tweeter_update (tweeter));
+}
+
+
+static void tune_task_init (void)
+{
+    melody = mmelody_init (&melody_info, TUNE_TASK_RATE, 
+			   (mmelody_callback_t) tweeter_note_play, tweeter);
+
+    mmelody_speed_set (melody, TUNE_BPM_RATE);
+
+    mmelody_play (melody, tune1);
+}
+
+
+static void tune_task (__unused__ void *data)
+{
+    mmelody_update (melody);
+}
+
+
+static void button_task_init (void)
+{
+    button_init ();
+}
+
+
+static void button_task (__unused__ void *data)
+{
+    button_update ();
+
+    if (button_push_event_p (BUTTON1))
+        mmelody_play (melody, tune1);
+}
+
+
+int main (void)
+{
+    task_t tasks[] =
+    {
+        {.func = tweeter_task, .period = TASK_RATE / TWEETER_TASK_RATE, .data = 0},
+        {.func = led_flash_task, .period = TASK_RATE / LED_TASK_RATE, .data = 0},
+        {.func = tune_task, .period = TASK_RATE / TUNE_TASK_RATE, .data = 0},
+        {.func = button_task, .period = TASK_RATE / BUTTON_TASK_RATE, .data = 0},
+    };
+
+    system_init ();
+
+    led_flash_task_init ();
+    tweeter_task_init ();
+    tune_task_init ();
+    button_task_init ();
+
+    task_schedule (tasks, 4);
+    return 0;
+}