refactor: move test-style examples to ./tests

13 files changed, 2794 insertions, 0 deletions

diff --git a/tests/test-bkp.cpp b/tests/test-bkp.cpp
new file mode 100644
index 0000000..719cac7
--- /dev/null
+++ b/tests/test-bkp.cpp
@@ -0,0 +1,80 @@
+#include <stdio.h>              // for snprintf()
+
+#include <wirish/wirish.h>
+#include <libmaple/bkp.h>
+#include <libmaple/iwdg.h>
+
+void print_bkp_contents();
+void write_to_bkp(uint16 val);
+
+#define comm Serial2
+
+void setup() {
+    pinMode(BOARD_BUTTON_PIN, INPUT);
+
+    comm.begin(9600);
+    comm.println("*** Beginning BKP test");
+
+    comm.println("Init...");
+    bkp_init();
+    comm.println("Done.");
+
+    print_bkp_contents();
+    write_to_bkp(10);
+    print_bkp_contents();
+
+    comm.println("Enabling backup writes.");
+    bkp_enable_writes();
+    write_to_bkp(20);
+    print_bkp_contents();
+
+    comm.println("Disabling backup writes.");
+    bkp_disable_writes();
+    write_to_bkp(30);
+    print_bkp_contents();
+
+    comm.println("Done testing backup registers; press button to enable "
+                    "independent watchdog (in order to cause a reset).");
+    waitForButtonPress(0);
+    iwdg_init(IWDG_PRE_4, 1);
+    comm.println();
+}
+
+void loop() {
+}
+
+void print_bkp_contents() {
+    comm.println("Backup data register contents:");
+    char buf[100];
+    for (int i = 1; i <= BKP_NR_DATA_REGS; i++) {
+        snprintf(buf, sizeof buf, "DR%d: %d ", i, bkp_read(i));
+        comm.print(buf);
+        if (i % 5 == 0) comm.println();
+    }
+    comm.println();
+}
+
+void write_to_bkp(uint16 val) {
+    comm.print("Attempting to write ");
+    comm.print(val);
+    comm.println(" to backup registers...");
+    for (int i = 1; i <= BKP_NR_DATA_REGS; i++) {
+        bkp_write(i, val);
+    }
+    comm.println("Done.");
+}
+
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    init();
+    setup();
+
+    while (1) {
+        loop();
+    }
+    return 0;
+}
+
diff --git a/tests/test-dac.cpp b/tests/test-dac.cpp
new file mode 100644
index 0000000..af188cc
--- /dev/null
+++ b/tests/test-dac.cpp
@@ -0,0 +1,51 @@
+/*
+ * Simple DAC test.
+ *
+ * Author: Marti Bolivar <mbolivar@leaflabs.com>
+ *
+ * This file is released into the public domain.
+ */
+
+#include <wirish/wirish.h>
+#include <libmaple/dac.h>
+
+uint16 count = 0;
+
+void setup() {
+    pinMode(BOARD_LED_PIN, OUTPUT);
+    digitalWrite(BOARD_LED_PIN, HIGH);
+
+    Serial1.begin(9600);
+    Serial1.println("**** Beginning DAC test");
+
+    Serial1.print("Init... ");
+    dac_init(DAC, DAC_CH1 | DAC_CH2);
+    Serial1.println("Done.");
+}
+
+void loop() {
+    toggleLED();
+    delay(100);
+
+    count += 100;
+    if (count > 4095) {
+        count = 0;
+    }
+
+    dac_write_channel(DAC, 1, 4095 - count);
+    dac_write_channel(DAC, 2, count);
+}
+
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}
+
diff --git a/tests/test-fsmc.cpp b/tests/test-fsmc.cpp
new file mode 100644
index 0000000..1621317
--- /dev/null
+++ b/tests/test-fsmc.cpp
@@ -0,0 +1,122 @@
+#include <stddef.h>             // for ptrdiff_t
+
+#include <wirish/wirish.h>
+#include <libmaple/fsmc.h>
+
+#ifndef BOARD_maple_native
+#error "Sorry, this example only works on Maple Native."
+#endif
+
+// Start of FSMC SRAM bank 1
+static uint16 *const sram_start = (uint16*)0x60000000;
+// End of Maple Native SRAM chip address space (512K 16-bit words)
+static uint16 *const sram_end = (uint16*)0x60100000;
+
+void test_single_write(void);
+void test_all_addresses(void);
+
+void setup() {
+    pinMode(BOARD_LED_PIN, OUTPUT);
+    digitalWrite(BOARD_LED_PIN, HIGH);
+
+    SerialUSB.read();
+    SerialUSB.println("*** Beginning RAM chip test");
+
+    test_single_write();
+    test_all_addresses();
+
+    SerialUSB.println("Tests pass, finished.");
+    SerialUSB.println("***\n");
+}
+
+void loop() {
+}
+
+void test_single_write() {
+    uint16 *ptr = sram_start;
+    uint16 tmp;
+
+    SerialUSB.print("Writing 0x1234... ");
+    *ptr = 0x1234;
+    SerialUSB.println("Done.");
+
+    SerialUSB.print("Reading... ");
+    tmp = *ptr;
+    SerialUSB.print("Done: 0x");
+    SerialUSB.println(tmp, HEX);
+
+    if (tmp != 0x1234) {
+        SerialUSB.println("Mismatch; abort.");
+        ASSERT(0);
+    }
+}
+
+void test_all_addresses() {
+    uint32 start, end;
+    uint16 count = 0;
+    uint16 *ptr;
+
+    SerialUSB.println("Now writing all memory addresses (unrolled loop)");
+    start = micros();
+    for (ptr = sram_start; ptr < sram_end;) {
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+        *ptr++ = count++;
+    }
+    end = micros();
+    SerialUSB.print("Done. Elapsed time (us): ");
+    SerialUSB.println(end - start);
+
+    SerialUSB.println("Validating writes.");
+    for (ptr = sram_start, count = 0; ptr < sram_end; ptr++, count++) {
+        uint16 value = *ptr;
+        if (value != count) {
+            SerialUSB.print("mismatch: 0x");
+            SerialUSB.print((uint32)ptr);
+            SerialUSB.print(" = 0x");
+            SerialUSB.print(value, HEX);
+            SerialUSB.print(", should be 0x");
+            SerialUSB.print(count, HEX);
+            SerialUSB.println(".");
+            ASSERT(0);
+        }
+    }
+    SerialUSB.println("Done; all writes seem valid.");
+
+    ptrdiff_t nwrites = sram_end - sram_start;
+    double us_per_write = double(end-start) / double(nwrites);
+    SerialUSB.print("Number of writes = ");
+    SerialUSB.print(nwrites);
+    SerialUSB.print("; avg. time per write = ");
+    SerialUSB.print(us_per_write);
+    SerialUSB.print(" us (");
+    SerialUSB.print(1 / us_per_write);
+    SerialUSB.println(" MHz)");
+}
+
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+
+    return 0;
+}
diff --git a/tests/test-print.cpp b/tests/test-print.cpp
new file mode 100644
index 0000000..bdc1894
--- /dev/null
+++ b/tests/test-print.cpp
@@ -0,0 +1,184 @@
+/*
+ * print-test.cpp
+ *
+ * Tests the various Print methods. (For USBSerial; assuming that
+ * writing a single character works, this should generalize to
+ * HardwareSerial).
+ *
+ * This file is released into the public domain.
+ */
+
+#include <wirish/wirish.h>
+#undef min
+#undef max
+
+// For snprintf()
+#include <stdio.h>
+// The <limits.h> that comes with newlib is missing LLONG_MAX, etc.
+#include <limits>
+
+using namespace std;
+
+#define BUF_SIZE 100
+char buf[BUF_SIZE];
+
+void test_numbers(void);
+void test_base_arithmetic(void);
+void test_floating_point(void);
+
+void print_separator(void);
+
+void setup() {
+    while (!SerialUSB.available())
+        continue;
+    SerialUSB.read();
+}
+
+void loop() {
+    SerialUSB.println("Testing Print methods.");
+    print_separator();
+
+    test_numbers();
+    print_separator();
+
+    test_base_arithmetic();
+    print_separator();
+
+    test_floating_point();
+    print_separator();
+
+    SerialUSB.println("Test finished.");
+    while (true) {
+        continue;
+    }
+}
+
+void test_numbers(void) {
+    SerialUSB.println("Numeric types:");
+
+    SerialUSB.print("unsigned char: ");
+    // prevent Print from treating it as an (extended) ASCII character:
+    SerialUSB.println((uint32)numeric_limits<unsigned char>::max());
+
+    SerialUSB.print("int: ");
+    SerialUSB.print(numeric_limits<int>::min());
+    SerialUSB.print(" -- ");
+    SerialUSB.println(numeric_limits<int>::max());
+
+    SerialUSB.print("unsigned int: ");
+    SerialUSB.print(numeric_limits<unsigned int>::max());
+    SerialUSB.println();
+
+    SerialUSB.print("long: ");
+    SerialUSB.print(numeric_limits<long>::min());
+    SerialUSB.print(" -- ");
+    SerialUSB.println(numeric_limits<long>::max());
+
+    SerialUSB.print("long long: ");
+    SerialUSB.print(numeric_limits<long long>::min());
+    SerialUSB.print(" -- ");
+    SerialUSB.println(numeric_limits<long long>::max());
+
+    SerialUSB.print("unsigned long long: ");
+    SerialUSB.println(numeric_limits<unsigned long long>::max());
+}
+
+void base_test(int base) {
+    SerialUSB.print("\tuint8: ");
+    SerialUSB.println(numeric_limits<uint8>::max(), base);
+    SerialUSB.print("\tint: ");
+    SerialUSB.print(numeric_limits<int>::max(), base);
+    SerialUSB.print(", unsigned int: ");
+    SerialUSB.println(numeric_limits<unsigned int>::max(), base);
+    SerialUSB.print("\tlong: ");
+    SerialUSB.print(numeric_limits<long>::max(), base);
+    SerialUSB.print(", unsigned long: ");
+    SerialUSB.println(numeric_limits<unsigned long>::max(), base);
+    SerialUSB.print("\tlong long: ");
+    SerialUSB.print(numeric_limits<long long>::max(), base);
+    SerialUSB.print(", unsigned long long: ");
+    SerialUSB.println(numeric_limits<unsigned long long>::max(), base);
+}
+
+void test_base_arithmetic(void) {
+    SerialUSB.println("Base arithmetic:");
+
+    SerialUSB.println("Binary:");
+    base_test(BIN);
+
+    SerialUSB.println("Octal:");
+    base_test(OCT);
+
+    SerialUSB.println("Decimal:");
+    base_test(DEC);
+
+    SerialUSB.println("Hexadecimal:");
+    base_test(HEX);
+}
+
+void test_floating_point(void) {
+    double dmax = numeric_limits<double>::max();
+
+    SerialUSB.println("Floating point:");
+
+    SerialUSB.print("println(-5.67): ");
+    SerialUSB.print(-5.67);
+    SerialUSB.print(". println(5.67, 5): ");
+    SerialUSB.println(5.67, 5);
+    SerialUSB.print("println((double)(LLONG_MAX - 10)):                 ");
+    SerialUSB.print((double)(numeric_limits<long long>::max() - 10));
+    SerialUSB.print("; from snprintf(): ");
+    snprintf(buf, BUF_SIZE, "%.2f",
+             (double)(numeric_limits<long long>::max() - 10));
+    SerialUSB.println(buf);
+    SerialUSB.print("println((double)LLONG_MAX / 2):                 ");
+    SerialUSB.print((double)(numeric_limits<long long>::max()) / 2);
+    SerialUSB.print("; from snprintf(): ");
+    snprintf(buf, BUF_SIZE, "%.2f",
+             (double)(numeric_limits<long long>::max()) / 2);
+    SerialUSB.println(buf);
+    SerialUSB.print("DBL_MAX:                 ");
+    SerialUSB.print(dmax);
+    SerialUSB.print("; from snprintf(): ");
+    snprintf(buf, BUF_SIZE, "%g", dmax);
+    SerialUSB.println(buf);
+    SerialUSB.print("-DBL_MAX / 2:                 ");
+    SerialUSB.print(-dmax / 2.0);
+    SerialUSB.print("; from snprintf(): ");
+    snprintf(buf, BUF_SIZE, "%g", -dmax / 2.0);
+    SerialUSB.println(buf);
+    SerialUSB.print("Double epsilon, round error: ");
+    SerialUSB.print(numeric_limits<double>::epsilon());
+    SerialUSB.print(", ");
+    SerialUSB.println(numeric_limits<double>::round_error());
+
+    SerialUSB.println();
+
+    float fmax = numeric_limits<float>::max();
+
+    SerialUSB.print("println(-5.67f): ");
+    SerialUSB.println(-5.67f);
+    SerialUSB.print("Float max: ");
+    SerialUSB.println(fmax);
+}
+
+void print_separator(void) {
+    SerialUSB.println();
+    SerialUSB.println(" ** ");
+    SerialUSB.println();
+}
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated objects that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (1) {
+        loop();
+    }
+    return 0;
+}
diff --git a/tests/test-ring-buffer-insertion.cpp b/tests/test-ring-buffer-insertion.cpp
new file mode 100644
index 0000000..2188b03
--- /dev/null
+++ b/tests/test-ring-buffer-insertion.cpp
@@ -0,0 +1,114 @@
+/*
+ * Simple ring_buffer test.
+ *
+ * Does a basic test of functionality on rb_full_count(), rb_reset(),
+ * rb_push_insert(), and rb_safe_insert().
+ *
+ * To test:
+ *
+ *     - Connect a serial monitor to SerialUSB
+ *     - Press any key
+ *
+ * This file is released into the public domain.
+ */
+
+#include <wirish/wirish.h>
+
+#include <libmaple/ring_buffer.h>
+
+#define BUF_SIZE 64
+ring_buffer ring_buf;
+ring_buffer *rb;
+uint8 rb_buffer[BUF_SIZE];
+
+void test_rb_push_insert(int num_bytes_to_insert);
+void test_rb_safe_insert(int num_bytes_to_insert);
+void test_rb_insertion_function(int num_bytes_to_insert,
+                                int (*insertion_fn)(ring_buffer*, uint8),
+                                const char insertion_fn_name[]);
+void print_rb_contents(void);
+
+void setup() {
+    rb = &ring_buf;
+    rb_init(rb, BUF_SIZE, rb_buffer);
+
+    while (!SerialUSB.available())
+        ;
+
+    SerialUSB.println("Beginning test.");
+    SerialUSB.println();
+}
+
+void loop() {
+    test_rb_push_insert(63);
+    SerialUSB.println("------------------------------");
+    test_rb_push_insert(64);
+    SerialUSB.println("------------------------------");
+    test_rb_safe_insert(63);
+    SerialUSB.println("------------------------------");
+    test_rb_safe_insert(64);
+    SerialUSB.println("------------------------------");
+
+    SerialUSB.println();
+    SerialUSB.println("Test finished.");
+    while (true)
+        ;
+}
+
+void test_rb_push_insert(int num_bytes_to_insert) {
+    test_rb_insertion_function(num_bytes_to_insert,
+                               rb_push_insert,
+                               "rb_push_insert()");
+}
+
+void test_rb_safe_insert(int num_bytes_to_insert) {
+    test_rb_insertion_function(num_bytes_to_insert,
+                               rb_safe_insert,
+                               "rb_safe_insert()");
+}
+
+void test_rb_insertion_function(int num_bytes_to_insert,
+                                int (*insertion_fn)(ring_buffer *, uint8),
+                                const char insertion_fn_name[]) {
+    SerialUSB.println("resetting ring buffer.");
+    rb_reset(rb);
+    print_rb_contents();
+
+    SerialUSB.print(insertion_fn_name);
+    SerialUSB.print("-ing ");
+    SerialUSB.print(num_bytes_to_insert);
+    SerialUSB.println(" bytes.");
+    for (uint8 i = 1; i <= num_bytes_to_insert; i++)
+        insertion_fn(rb, i);
+
+    uint16 count = rb_full_count(rb);
+    SerialUSB.print("rb_full_count(rb) = ");
+    SerialUSB.println(count);
+
+    print_rb_contents();
+}
+
+void print_rb_contents() {
+    uint16 count = rb_full_count(rb);
+    SerialUSB.print("ring buffer contents: ");
+    for (uint16 i = 0; i < count; i++) {
+        SerialUSB.print((int)rb_remove(rb));
+        if (i < count - 1) SerialUSB.print(", ");
+    }
+    SerialUSB.println();
+}
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated objects that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}
diff --git a/tests/test-serial-flush.cpp b/tests/test-serial-flush.cpp
new file mode 100644
index 0000000..409d1f9
--- /dev/null
+++ b/tests/test-serial-flush.cpp
@@ -0,0 +1,38 @@
+/*
+ * Tests the "flush" Serial function.
+ */
+
+#include <wirish/wirish.h>
+
+void setup() {
+    Serial1.begin(9600);
+    Serial1.println("Hello world!");
+}
+
+void loop() {
+    Serial1.println("Waiting for multiple input...");
+    while (Serial1.available() < 5)
+        ;
+    Serial1.println(Serial1.read());
+    Serial1.println(Serial1.read());
+    Serial1.flush();
+
+    if (Serial1.available()) {
+        Serial1.println("FAIL! Still had junk in the buffer...");
+    }
+}
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated objects that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}
diff --git a/tests/test-serialusb.cpp b/tests/test-serialusb.cpp
new file mode 100644
index 0000000..098e445
--- /dev/null
+++ b/tests/test-serialusb.cpp
@@ -0,0 +1,126 @@
+// Tests SerialUSB functionality.
+
+#include <wirish/wirish.h>
+#include "usb_cdcacm.h"
+
+#define QUICKPRINT  0
+#define BIGSTUFF    1
+#define NUMBERS     2
+#define SIMPLE      3
+#define ONOFF       4
+
+uint32 state = 0;
+
+void setup() {
+    /* Set up the LED to blink  */
+    pinMode(BOARD_LED_PIN, OUTPUT);
+
+    /* Set up Serial2 for use as a debug channel */
+    Serial2.begin(9600);
+    Serial2.println("This is the debug channel. Press any key.");
+    while (!Serial2.available())
+        ;
+    Serial2.read();
+}
+
+uint8 c1 = '-';
+
+void loop() {
+    toggleLED();
+    delay(1000);
+
+    if (Serial2.available()) {
+        Serial2.read();
+        state++;
+    }
+
+    switch (state) {
+        case QUICKPRINT:
+            for (int i = 0; i < 30; i++) {
+                usb_cdcacm_putc((char)c1, 1);
+                SerialUSB.print('.');
+                SerialUSB.print('|');
+            }
+            Serial2.println(SerialUSB.pending(), DEC);
+            SerialUSB.println();
+            break;
+        case BIGSTUFF:
+            SerialUSB.println("0123456789012345678901234567890123456789"
+                              "0123456789012345678901234567890123456789"
+                              "012345678901234567890");
+            SerialUSB.println((int64)123456789, DEC);
+            SerialUSB.println(3.1415926535);
+            Serial2.println(SerialUSB.pending(), DEC);
+            break;
+        case NUMBERS:
+            SerialUSB.println("Numbers! -----------------------------");
+            Serial2.println("Numbers! -----------------------------");
+            SerialUSB.println('1');
+            Serial2.println('1');
+            SerialUSB.println(1, DEC);
+            Serial2.println(1, DEC);
+            SerialUSB.println(-1, DEC);
+            Serial2.println(-1, DEC);
+            SerialUSB.println(3.14159265);
+            Serial2.println(3.14159265);
+            SerialUSB.println(123456789, DEC);
+            Serial2.println(123456789, DEC);
+            SerialUSB.println(-123456789, DEC);
+            Serial2.println(-123456789, DEC);
+            SerialUSB.println(65535, HEX);
+            Serial2.println(65535, HEX);
+            break;
+        case SIMPLE:
+            Serial2.println("Trying write('a')");
+            SerialUSB.write('a');
+            Serial2.println("Trying write(\"b\")");
+            SerialUSB.write("b");
+            Serial2.println("Trying print('c')");
+            SerialUSB.print('c');
+            Serial2.println("Trying print(\"d\")");
+            SerialUSB.print("d");
+            Serial2.println("Trying print(\"efg\")");
+            SerialUSB.print("efg");
+            Serial2.println("Trying println(\"hij\\n\\r\")");
+            SerialUSB.print("hij\n\r");
+            SerialUSB.write(' ');
+            SerialUSB.println();
+            Serial2.println("Trying println(123456789, DEC)");
+            SerialUSB.println(123456789, DEC);
+            Serial2.println("Trying println(3.141592)");
+            SerialUSB.println(3.141592);
+            Serial2.println("Trying println(\"DONE\")");
+            SerialUSB.println("DONE");
+            break;
+        case ONOFF:
+            Serial2.println("Shutting down...");
+            SerialUSB.println("Shutting down...");
+            SerialUSB.end();
+            Serial2.println("Waiting 4 seconds...");
+            delay(4000);
+            Serial2.println("Starting up...");
+            SerialUSB.begin();
+            SerialUSB.println("Hello World!");
+            Serial2.println("Waiting 4 seconds...");
+            delay(4000);
+            state++;
+            break;
+        default:
+            state = 0;
+    }
+}
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated objects that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}
diff --git a/tests/test-servo.cpp b/tests/test-servo.cpp
new file mode 100644
index 0000000..6f6e3ba
--- /dev/null
+++ b/tests/test-servo.cpp
@@ -0,0 +1,152 @@
+/*
+ * Basic Servo library test program.
+ *
+ * Setup:
+ *
+ * - Connect a potentiometer to POT_PIN (default pin 15)
+ * - Connect an oscilloscope to SERVO_PIN1 (default pin 5) and
+ *   SERVO_PIN2 (default pin 6).
+ * - Connect a serial monitor to SerialUSB
+ *
+ * The potentiometer controls the target angle for each of two Servo
+ * objects, one with angles in [-90, 90], and another in [0, 180].
+ * Servo pulse width range is [1000, 2000].
+ *
+ * Serial2 will tell you what inputs it's giving to each servo object,
+ * and some information it gets back.  Pressing the button
+ * detaches/reattaches the Servo objects.
+ *
+ * Tests you should perform:
+ *
+ * - Check calculated pulse widths for each servo's target angle
+ * - Check that calculated pulse widths match actual pulse widths
+ * - Check that the period of the pulse train is roughly 20 ms
+ * - Check that the pulses stop when detached, and resume when reattached
+ * - Check that Servo::write() and Servo::read() round-trip properly
+ *
+ * This file is released into the public domain.
+ */
+
+#include <stdio.h>
+
+#include <wirish/wirish.h>
+
+#include "libraries/Servo/Servo.h"
+
+#define POT_PIN 15
+
+#define MIN_PW 1000
+#define MAX_PW 2000
+
+#define SERVO_PIN1 5
+#define MIN_ANGLE1 0
+#define MAX_ANGLE1 180
+
+#define SERVO_PIN2 6
+#define MIN_ANGLE2 (-90)
+#define MAX_ANGLE2 90
+
+Servo servo1;
+Servo servo2;
+
+#define BUF_SIZE 100
+char buf[BUF_SIZE];
+
+#define print_buf(fmt, ...) do {                  \
+    snprintf(buf, BUF_SIZE, fmt, __VA_ARGS__);    \
+    Serial2.println(buf); } while (0)
+
+int averageAnalogReads(int);
+void attach();
+void detach();
+
+void setup() {
+    pinMode(POT_PIN, INPUT_ANALOG);
+    pinMode(BOARD_BUTTON_PIN, INPUT);
+    pinMode(BOARD_LED_PIN, OUTPUT);
+
+    Serial2.begin(9600);
+
+    servo1.attach(SERVO_PIN1, MIN_PW, MAX_PW, MIN_ANGLE1, MAX_ANGLE1);
+    servo2.attach(SERVO_PIN2, MIN_PW, MAX_PW, MIN_ANGLE2, MAX_ANGLE2);
+
+    ASSERT(servo1.attachedPin() == SERVO_PIN1);
+    ASSERT(servo2.attachedPin() == SERVO_PIN2);
+}
+
+void loop() {
+    delay(250);
+    toggleLED();
+
+    if (isButtonPressed()) {
+        if (servo1.attached()) detach();
+        else                   attach();
+    }
+
+    if (!servo1.attached()) return;
+
+    int32 average = averageAnalogReads(250);
+    int16 angle1 = (int16)map(average, 0, 4095, MIN_ANGLE1, MAX_ANGLE1);
+    int16 angle2 = (int16)map(average, 0, 4095, MIN_ANGLE2, MAX_ANGLE2);
+
+    print_buf("pot reading = %d, angle 1 = %d, angle 2 = %d.",
+              average, angle1, angle2);
+
+    servo1.write(angle1);
+    servo2.write(angle2);
+
+    int16 read1 = servo1.read();
+    int16 read2 = servo2.read();
+
+    print_buf("write/read angle 1: %d/%d, angle 2: %d/%d",
+              angle1, read1, angle2, read2);
+
+    ASSERT(abs(angle1 - read1) <= 1);
+    ASSERT(abs(angle2 - read2) <= 1);
+
+    print_buf("pulse width 1: %d, pulse width 2: %d",
+              servo1.readMicroseconds(), servo2.readMicroseconds());
+
+     Serial2.println("\n--------------------------\n");
+}
+
+int32 averageAnalogReads(int n) {
+    uint64 total = 0;
+
+    for (int i = 0; i < n; i++) {
+        total += analogRead(POT_PIN);
+    }
+
+    return (int32)(total / n);
+}
+
+void attach() {
+    Serial2.println("attaching");
+    servo1.attach(SERVO_PIN1);
+    servo2.attach(SERVO_PIN2);
+    ASSERT(servo1.attachedPin() == SERVO_PIN1);
+    ASSERT(servo2.attachedPin() == SERVO_PIN2);
+}
+
+void detach() {
+    Serial2.println("detaching");
+    servo1.detach();
+    servo2.detach();
+    ASSERT(!servo1.attached());
+    ASSERT(!servo2.attached());
+}
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated objects that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}
diff --git a/tests/test-session.cpp b/tests/test-session.cpp
new file mode 100644
index 0000000..284b4b0
--- /dev/null
+++ b/tests/test-session.cpp
@@ -0,0 +1,938 @@
+// Interactive Test Session for LeafLabs Maple
+// Copyright (c) 2010 LeafLabs LLC.
+//
+// Useful for testing Maple features and troubleshooting.
+// Communicates over SerialUSB.
+
+#include <string.h>
+
+#include <wirish/wirish.h>
+
+// ASCII escape character
+#define ESC       ((uint8)27)
+
+// Default USART baud rate
+#define BAUD     9600
+
+// Number of times to sample a pin per ADC noise measurement
+#define N_ADC_NOISE_MEASUREMENTS 40
+
+uint8 gpio_state[BOARD_NR_GPIO_PINS];
+
+const char* dummy_data = ("123456789012345678901234567890\r\n"
+                          "123456789012345678901234567890\r\n");
+
+// Commands
+void cmd_print_help(void);
+void cmd_adc_stats(void);
+void cmd_stressful_adc_stats(void);
+void cmd_everything(void);
+void cmd_serial1_serial3(void);
+void cmd_serial1_echo(void);
+void cmd_gpio_monitoring(void);
+void cmd_sequential_adc_reads(void);
+void cmd_gpio_qa(void);
+void cmd_sequential_gpio_toggling(void);
+void cmd_gpio_toggling(void);
+void cmd_sequential_debug_gpio_toggling(void);
+void cmd_debug_gpio_toggling(void);
+void cmd_but_test(void);
+void cmd_sequential_pwm_test(void);
+void cmd_servo_sweep(void);
+void cmd_board_info(void);
+
+// Helper functions
+void measure_adc_noise(uint8 pin);
+void fast_gpio(int pin);
+void serial_baud_test(HardwareSerial **serials, int n, unsigned baud);
+void serial_echo_test(HardwareSerial *serial, unsigned baud);
+void init_all_timers(uint16 prescale);
+void enable_usarts(void);
+void disable_usarts(void);
+void print_board_array(const char* msg, const uint8 arr[], int len);
+
+// -- setup() and loop() ------------------------------------------------------
+
+void setup() {
+    // Set up the LED to blink
+    pinMode(BOARD_LED_PIN, OUTPUT);
+
+    // Start up the serial ports
+    Serial1.begin(BAUD);
+    Serial2.begin(BAUD);
+    Serial3.begin(BAUD);
+
+    // Send a message out over SerialUSB interface
+    SerialUSB.println(" ");
+    SerialUSB.println("    __   __             _      _");
+    SerialUSB.println("   |  \\/  | __ _ _ __ | | ___| |");
+    SerialUSB.println("   | |\\/| |/ _` | '_ \\| |/ _ \\ |");
+    SerialUSB.println("   | |  | | (_| | |_) | |  __/_|");
+    SerialUSB.println("   |_|  |_|\\__,_| .__/|_|\\___(_)");
+    SerialUSB.println("                 |_|");
+    SerialUSB.println("                              by leaflabs");
+    SerialUSB.println("");
+    SerialUSB.println("");
+    SerialUSB.println("Maple interactive test program (type '?' for help)");
+    SerialUSB.println("-------------------------------------------------------"
+                      "---");
+    SerialUSB.print("> ");
+
+}
+
+void loop () {
+    toggleLED();
+    delay(250);
+
+    while (SerialUSB.available()) {
+        uint8 input = SerialUSB.read();
+        SerialUSB.println((char)input);
+
+        switch(input) {
+        case '\r':
+            break;
+
+        case ' ':
+            SerialUSB.println("spacebar, nice!");
+            break;
+
+        case '?':
+        case 'h':
+            cmd_print_help();
+            break;
+
+        case 'u':
+            SerialUSB.println("Hello World!");
+            break;
+
+        case 'w':
+            Serial1.println("Hello World!");
+            Serial2.println("Hello World!");
+            Serial3.println("Hello World!");
+            break;
+
+        case 'm':
+            cmd_serial1_serial3();
+            break;
+
+        case 'E':
+            cmd_serial1_echo();
+            break;
+
+        case '.':
+            while (!SerialUSB.available()) {
+                Serial1.print(".");
+                Serial2.print(".");
+                Serial3.print(".");
+                SerialUSB.print(".");
+            }
+            break;
+
+        case 'd':
+            SerialUSB.println("Disabling USB.  Press BUT to re-enable.");
+            SerialUSB.end();
+            pinMode(BOARD_BUTTON_PIN, INPUT);
+            while (!isButtonPressed())
+                ;
+            SerialUSB.begin();
+            break;
+
+        case 'n':
+            cmd_adc_stats();
+            break;
+
+        case 'N':
+            cmd_stressful_adc_stats();
+            break;
+
+        case 'e':
+            cmd_everything();
+            break;
+
+        case 'W':
+            while (!SerialUSB.available()) {
+                Serial1.print(dummy_data);
+                Serial2.print(dummy_data);
+                Serial3.print(dummy_data);
+            }
+            break;
+
+        case 'U': {
+            SerialUSB.println("Dumping data to USB. Press any key.");
+            int nprints = 0;
+            int start = millis();
+            while (!SerialUSB.available()) {
+                SerialUSB.print(dummy_data);
+                nprints++;
+            }
+            int elapsed = millis() - start;
+            SerialUSB.read();   // consume available character
+            size_t nbytes = nprints * strlen(dummy_data);
+            SerialUSB.println();
+            SerialUSB.print("Sent ");
+            SerialUSB.print(nbytes);
+            SerialUSB.print(" bytes (");
+            SerialUSB.print((nbytes / (double)elapsed) * (1000.0 / 1024.0));
+            SerialUSB.println(" kB/sec)");
+        }
+            break;
+
+        case 'g':
+            cmd_sequential_gpio_toggling();
+            break;
+
+        case 'G':
+            cmd_gpio_toggling();
+            break;
+
+        case 'j':
+            cmd_sequential_debug_gpio_toggling();
+            break;
+
+        case 'J':
+            cmd_debug_gpio_toggling();
+            break;
+
+        case 'B':
+            cmd_but_test();
+            break;
+
+        case 'f':
+            SerialUSB.println("Wiggling D4 as fast as possible in bursts. "
+                         "Press any key.");
+            pinMode(4, OUTPUT);
+            while (!SerialUSB.available()) {
+                fast_gpio(4);
+                delay(1);
+            }
+            break;
+
+        case 'p':
+            cmd_sequential_pwm_test();
+            break;
+
+        case '_':
+            SerialUSB.println("Delaying for 5 seconds...");
+            delay(5000);
+            break;
+
+        // Be sure to update cmd_print_help() if you implement these:
+
+        case 't':               // TODO
+            SerialUSB.println("Unimplemented.");
+            break;
+
+        case 'T':               // TODO
+            SerialUSB.println("Unimplemented.");
+            break;
+
+        case 's':
+            cmd_servo_sweep();
+            break;
+
+        // Be sure to update cmd_print_help() if you implement these:
+
+        case 'i':               // TODO
+            SerialUSB.println("Unimplemented.");
+            break;
+
+        case 'I':               // TODO
+            SerialUSB.println("Unimplemented.");
+            break;
+
+        case 'r':
+            cmd_gpio_monitoring();
+            break;
+
+        case 'a':
+            cmd_sequential_adc_reads();
+            break;
+
+        case 'b':
+            cmd_board_info();
+            break;
+
+        case '+':
+            cmd_gpio_qa();
+            break;
+
+        default: // -------------------------------
+            SerialUSB.print("Unexpected byte: 0x");
+            SerialUSB.print((int)input, HEX);
+            SerialUSB.println(", press h for help.");
+        }
+
+        SerialUSB.print("> ");
+    }
+}
+
+// -- Commands ----------------------------------------------------------------
+
+void cmd_print_help(void) {
+    SerialUSB.println("");
+    SerialUSB.println("Command Listing");
+    SerialUSB.println("\t?: print this menu");
+    SerialUSB.println("\td: Disable SerialUSB (press button to re-enable)");
+    SerialUSB.println("\th: print this menu");
+    SerialUSB.println("\tw: print Hello World on all 3 USARTS");
+    SerialUSB.println("\tn: measure noise and do statistics");
+    SerialUSB.println("\tN: measure noise and do statistics with background "
+                      "stuff");
+    SerialUSB.println("\ta: show realtime ADC info");
+    SerialUSB.println("\t.: echo '.' until new input");
+    SerialUSB.println("\tu: print Hello World on USB");
+    SerialUSB.println("\t_: do as little as possible for a couple seconds "
+                      "(delay)");
+    SerialUSB.println("\tp: test all PWM channels sequentially");
+    SerialUSB.println("\tW: dump data as fast as possible on all 3 USARTS");
+    SerialUSB.println("\tU: dump data as fast as possible over USB"
+                      " and measure data rate");
+    SerialUSB.println("\tg: toggle GPIOs sequentially");
+    SerialUSB.println("\tG: toggle GPIOs at the same time");
+    SerialUSB.println("\tj: toggle debug port GPIOs sequentially");
+    SerialUSB.println("\tJ: toggle debug port GPIOs simultaneously");
+    SerialUSB.println("\tB: test the built-in button");
+    SerialUSB.println("\tf: toggle pin 4 as fast as possible in bursts");
+    SerialUSB.println("\tr: monitor and print GPIO status changes");
+    SerialUSB.println("\ts: output a sweeping servo PWM on all PWM channels");
+    SerialUSB.println("\tm: output data on USART1 and USART3 at various "
+                      "baud rates");
+    SerialUSB.println("\tE: echo data on USART1 at various baud rates");
+    SerialUSB.println("\tb: print information about the board.");
+    SerialUSB.println("\t+: test shield mode (for quality assurance testing)");
+
+    SerialUSB.println("Unimplemented:");
+    SerialUSB.println("\te: do everything all at once until new input");
+    SerialUSB.println("\tt: output a 1khz squarewave on all GPIOs");
+    SerialUSB.println("\tT: output a 1hz squarewave on all GPIOs");
+    SerialUSB.println("\ti: print out a bunch of info about system state");
+    SerialUSB.println("\tI: print out status of all headers");
+}
+
+void cmd_adc_stats(void) {
+    SerialUSB.println("Taking ADC noise stats.  Press ESC to stop, "
+                      "'R' to repeat same pin, anything else for next pin.");
+
+    uint32 i = 0;
+    while (i < BOARD_NR_ADC_PINS) {
+        measure_adc_noise(boardADCPins[i]);
+
+        SerialUSB.println("----------");
+        uint8 c = SerialUSB.read();
+        if (c == ESC) {
+            break;
+        } else if (c != 'r' && c != 'R') {
+            i++;
+        }
+    }
+}
+
+void cmd_stressful_adc_stats(void) {
+    SerialUSB.println("Taking ADC noise stats under duress.  Press ESC to "
+                      "stop, 'R' to repeat same pin, anything else for next "
+                      "pin.");
+
+    uint32 i = 0;
+    while (i < BOARD_NR_ADC_PINS) {
+        // use PWM to create digital noise
+        for (uint32 j = 0; j < BOARD_NR_PWM_PINS; j++) {
+            if (boardADCPins[i] != boardPWMPins[j]) {
+                pinMode(boardPWMPins[j], PWM);
+                pwmWrite(boardPWMPins[j], 1000 + i);
+            }
+        }
+
+        measure_adc_noise(boardADCPins[i]);
+
+        // turn off the noise
+        for (uint32 j = 0; j < BOARD_NR_PWM_PINS; j++) {
+            if (boardADCPins[i] != boardPWMPins[j]) {
+                pinMode(boardPWMPins[j], OUTPUT);
+                digitalWrite(boardPWMPins[j], LOW);
+            }
+        }
+
+        SerialUSB.println("----------");
+        uint8 c = SerialUSB.read();
+        if (c == ESC) {
+            break;
+        } else if (c != 'r' && c != 'R') {
+            i++;
+        }
+    }
+}
+
+void cmd_everything(void) { // TODO
+    // Be sure to update cmd_print_help() if you implement this.
+
+    // print to usart
+    // print to usb
+    // toggle gpios
+    // enable pwm
+    SerialUSB.println("Unimplemented.");
+}
+
+void cmd_serial1_serial3(void) {
+    HardwareSerial *serial_1_and_3[] = {&Serial1, &Serial3};
+
+    SerialUSB.println("Testing 57600 baud on USART1 and USART3. "
+                      "Press any key to stop.");
+    serial_baud_test(serial_1_and_3, 2, 57600);
+    SerialUSB.read();
+
+    SerialUSB.println("Testing 115200 baud on USART1 and USART3. "
+                      "Press any key to stop.");
+    serial_baud_test(serial_1_and_3, 2, 115200);
+    SerialUSB.read();
+
+    SerialUSB.println("Testing 9600 baud on USART1 and USART3. "
+                      "Press any key to stop.");
+    serial_baud_test(serial_1_and_3, 2, 9600);
+    SerialUSB.read();
+
+    SerialUSB.println("Resetting USART1 and USART3...");
+    Serial1.begin(BAUD);
+    Serial3.begin(BAUD);
+}
+
+void cmd_serial1_echo(void) {
+    SerialUSB.println("Testing serial echo at various baud rates. "
+                      "Press any key for next baud rate, or ESC to quit "
+                      "early.");
+    while (!SerialUSB.available())
+        ;
+
+    if (SerialUSB.read() == ESC) return;
+    SerialUSB.println("Testing 115200 baud on USART1.");
+    serial_echo_test(&Serial1, 115200);
+
+    if (SerialUSB.read() == ESC) return;
+    SerialUSB.println("Testing 57600 baud on USART1.");
+    serial_echo_test(&Serial1, 57600);
+
+    if (SerialUSB.read() == ESC) return;
+    SerialUSB.println("Testing 9600 baud on USART1.");
+    serial_echo_test(&Serial1, 9600);
+}
+
+void cmd_gpio_monitoring(void) {
+    SerialUSB.println("Monitoring pin state changes. Press any key to stop.");
+
+    for (int i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+        if (boardUsesPin(i))
+            continue;
+        pinMode(i, INPUT_PULLDOWN);
+        gpio_state[i] = (uint8)digitalRead(i);
+    }
+
+    while (!SerialUSB.available()) {
+        for (int i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+            if (boardUsesPin(i))
+                continue;
+
+            uint8 current_state = (uint8)digitalRead(i);
+            if (current_state != gpio_state[i]) {
+                SerialUSB.print("State change on pin ");
+                SerialUSB.print(i, DEC);
+                if (current_state) {
+                    SerialUSB.println(":\tHIGH");
+                } else {
+                    SerialUSB.println(":\tLOW");
+                }
+                gpio_state[i] = current_state;
+            }
+        }
+    }
+
+    for (int i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+        if (boardUsesPin(i))
+            continue;
+        pinMode(i, OUTPUT);
+    }
+}
+
+void cmd_sequential_adc_reads(void) {
+    SerialUSB.print("Sequentially reading most ADC ports.");
+    SerialUSB.println("Press any key for next port, or ESC to stop.");
+
+    for (uint32 i = 0; i < BOARD_NR_ADC_PINS; i++) {
+        if (boardUsesPin(boardADCPins[i]))
+            continue;
+
+        SerialUSB.print("Reading pin ");
+        SerialUSB.print(boardADCPins[i], DEC);
+        SerialUSB.println("...");
+        pinMode(boardADCPins[i], INPUT_ANALOG);
+        while (!SerialUSB.available()) {
+            int sample = analogRead(boardADCPins[i]);
+            SerialUSB.print(boardADCPins[i], DEC);
+            SerialUSB.print("\t");
+            SerialUSB.print(sample, DEC);
+            SerialUSB.print("\t");
+            SerialUSB.print("|");
+            for (int j = 0; j < 4096; j += 100) {
+                if (sample >= j) {
+                    SerialUSB.print("#");
+                } else {
+                    SerialUSB.print(" ");
+                }
+            }
+            SerialUSB.print("| ");
+            for (int j = 0; j < 12; j++) {
+                if (sample & (1 << (11 - j))) {
+                    SerialUSB.print("1");
+                } else {
+                    SerialUSB.print("0");
+                }
+            }
+            SerialUSB.println();
+        }
+        pinMode(boardADCPins[i], OUTPUT);
+        digitalWrite(boardADCPins[i], 0);
+        if (SerialUSB.read() == ESC)
+            break;
+    }
+}
+
+bool test_single_pin_is_high(int high_pin, const char* err_msg) {
+    bool ok = true;
+    for (int i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+        if (boardUsesPin(i)) continue;
+
+        if (digitalRead(i) == HIGH && i != high_pin) {
+            SerialUSB.println();
+            SerialUSB.print("\t*** FAILURE! pin ");
+            SerialUSB.print(i, DEC);
+            SerialUSB.print(' ');
+            SerialUSB.println(err_msg);
+            ok = false;
+        }
+    }
+    return ok;
+}
+
+bool wait_for_low_transition(uint8 pin) {
+    uint32 start = millis();
+    while (millis() - start < 2000) {
+        if (digitalRead(pin) == LOW) {
+            return true;
+        }
+    }
+    return false;
+}
+
+void cmd_gpio_qa(void) {
+    bool all_pins_ok = true;
+    const int not_a_pin = -1;
+    SerialUSB.println("Doing QA testing for unused GPIO pins.");
+
+    for (int i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+        if (boardUsesPin(i)) continue;
+
+        pinMode(i, INPUT);
+    }
+
+    SerialUSB.println("Waiting to start.");
+    ASSERT(!boardUsesPin(0));
+    while (digitalRead(0) == LOW) continue;
+
+    for (int i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+        if (boardUsesPin(i)) {
+            SerialUSB.print("Skipping pin ");
+            SerialUSB.println(i, DEC);
+            continue;
+        }
+        bool pin_ok = true;
+        SerialUSB.print("Checking pin ");
+        SerialUSB.print(i, DEC);
+        while (digitalRead(i) == LOW) continue;
+
+        pin_ok = pin_ok && test_single_pin_is_high(i, "is also HIGH");
+
+        if (!wait_for_low_transition(i)) {
+            SerialUSB.println("Transition to low timed out; something is "
+                              "very wrong.  Aborting test.");
+            return;
+        }
+
+        pin_ok = pin_ok && test_single_pin_is_high(not_a_pin, "is still HIGH");
+
+        if (pin_ok) {
+            SerialUSB.println(": ok");
+        }
+
+        all_pins_ok = all_pins_ok && pin_ok;
+    }
+
+    if (all_pins_ok) {
+        SerialUSB.println("Finished; test passes.");
+    } else {
+        SerialUSB.println("**** TEST FAILS *****");
+    }
+
+    for (int i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+        if (boardUsesPin(i)) continue;
+
+        pinMode(i, OUTPUT);
+        digitalWrite(i, LOW);
+        gpio_state[i] = 0;
+    }
+}
+
+void cmd_sequential_gpio_toggling(void) {
+    SerialUSB.println("Sequentially toggling all unused pins. "
+                      "Press any key for next pin, ESC to stop.");
+
+    for (uint32 i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+        if (boardUsesPin(i))
+            continue;
+
+        SerialUSB.print("Toggling pin ");
+        SerialUSB.print((int)i, DEC);
+        SerialUSB.println("...");
+
+        pinMode(i, OUTPUT);
+        do {
+            togglePin(i);
+        } while (!SerialUSB.available());
+
+        digitalWrite(i, LOW);
+        if (SerialUSB.read() == ESC)
+            break;
+    }
+}
+
+void cmd_gpio_toggling(void) {
+    SerialUSB.println("Toggling all unused pins simultaneously. "
+                      "Press any key to stop.");
+
+    for (uint32 i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+        if (boardUsesPin(i))
+            continue;
+        pinMode(i, OUTPUT);
+    }
+
+    while (!SerialUSB.available()) {
+        for (uint32 i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+            if (boardUsesPin(i))
+                continue;
+            togglePin(i);
+        }
+    }
+
+    for (uint32 i = 0; i < BOARD_NR_GPIO_PINS; i++) {
+        if (boardUsesPin(i))
+            continue;
+        digitalWrite(i, LOW);
+    }
+}
+
+uint8 debugGPIOPins[] = {BOARD_JTMS_SWDIO_PIN,
+                         BOARD_JTCK_SWCLK_PIN,
+                         BOARD_JTDI_PIN,
+                         BOARD_JTDO_PIN,
+                         BOARD_NJTRST_PIN};
+
+#define N_DEBUG_PINS 5
+
+void cmd_sequential_debug_gpio_toggling(void) {
+    SerialUSB.println("Toggling all debug (JTAG/SWD) pins sequentially. "
+                      "This will permanently disable debug port "
+                      "functionality.");
+    disableDebugPorts();
+
+    for (int i = 0; i < N_DEBUG_PINS; i++) {
+        pinMode(debugGPIOPins[i], OUTPUT);
+    }
+
+    for (int i = 0; i < N_DEBUG_PINS; i++) {
+        int pin = debugGPIOPins[i];
+        SerialUSB.print("Toggling pin ");
+        SerialUSB.print(pin, DEC);
+        SerialUSB.println("...");
+
+        pinMode(pin, OUTPUT);
+        do {
+            togglePin(pin);
+        } while (!SerialUSB.available());
+
+        digitalWrite(pin, LOW);
+        if (SerialUSB.read() == ESC)
+            break;
+    }
+
+    for (int i = 0; i < N_DEBUG_PINS; i++) {
+        digitalWrite(debugGPIOPins[i], 0);
+    }
+}
+
+void cmd_debug_gpio_toggling(void) {
+    SerialUSB.println("Toggling debug GPIO simultaneously. "
+                      "This will permanently disable JTAG and Serial Wire "
+                      "debug port functionality. "
+                      "Press any key to stop.");
+    disableDebugPorts();
+
+    for (uint32 i = 0; i < N_DEBUG_PINS; i++) {
+        pinMode(debugGPIOPins[i], OUTPUT);
+    }
+
+    while (!SerialUSB.available()) {
+        for (uint32 i = 0; i < N_DEBUG_PINS; i++) {
+            togglePin(debugGPIOPins[i]);
+        }
+    }
+
+    for (uint32 i = 0; i < N_DEBUG_PINS; i++) {
+        digitalWrite(debugGPIOPins[i], LOW);
+    }
+}
+
+void cmd_but_test(void) {
+    SerialUSB.println("Press the button to test.  Press any key to stop.");
+    pinMode(BOARD_BUTTON_PIN, INPUT);
+
+    while (!SerialUSB.available()) {
+        if (isButtonPressed()) {
+            uint32 tstamp = millis();
+            SerialUSB.print("Button press detected, timestamp: ");
+            SerialUSB.println(tstamp);
+        }
+    }
+    SerialUSB.read();
+}
+
+void cmd_sequential_pwm_test(void) {
+    SerialUSB.println("Sequentially testing PWM on all unused pins. "
+                      "Press any key for next pin, ESC to stop.");
+
+    for (uint32 i = 0; i < BOARD_NR_PWM_PINS; i++) {
+        if (boardUsesPin(i))
+            continue;
+
+        SerialUSB.print("PWM out on header D");
+        SerialUSB.print(boardPWMPins[i], DEC);
+        SerialUSB.println("...");
+        pinMode(boardPWMPins[i], PWM);
+        pwmWrite(boardPWMPins[i], 16000);
+
+        while (!SerialUSB.available()) {
+            delay(10);
+        }
+
+        pinMode(boardPWMPins[i], OUTPUT);
+        digitalWrite(boardPWMPins[i], 0);
+        if (SerialUSB.read() == ESC)
+            break;
+    }
+}
+
+void cmd_servo_sweep(void) {
+    SerialUSB.println("Testing all PWM headers with a servo sweep. "
+                      "Press any key to stop.");
+    SerialUSB.println();
+
+    disable_usarts();
+    init_all_timers(21);
+
+    for (uint32 i = 0; i < BOARD_NR_PWM_PINS; i++) {
+        if (boardUsesPin(i))
+            continue;
+        pinMode(boardPWMPins[i], PWM);
+        pwmWrite(boardPWMPins[i], 4000);
+    }
+
+    // 1.25ms = 4096counts = 0deg
+    // 1.50ms = 4915counts = 90deg
+    // 1.75ms = 5734counts = 180deg
+    int rate = 4096;
+    while (!SerialUSB.available()) {
+        rate += 20;
+        if (rate > 5734)
+            rate = 4096;
+        for (uint32 i = 0; i < BOARD_NR_PWM_PINS; i++) {
+            if (boardUsesPin(i))
+                continue;
+            pwmWrite(boardPWMPins[i], rate);
+        }
+        delay(20);
+    }
+
+    for (uint32 i = 0; i < BOARD_NR_PWM_PINS; i++) {
+        if (boardUsesPin(i))
+            continue;
+        pinMode(boardPWMPins[i], OUTPUT);
+    }
+    init_all_timers(1);
+    enable_usarts();
+}
+
+void cmd_board_info(void) {     // TODO print more information
+    SerialUSB.println("Board information");
+    SerialUSB.println("=================");
+
+    SerialUSB.print("* Clock speed (MHz): ");
+    SerialUSB.println(CYCLES_PER_MICROSECOND);
+
+    SerialUSB.print("* BOARD_LED_PIN: ");
+    SerialUSB.println(BOARD_LED_PIN);
+
+    SerialUSB.print("* BOARD_BUTTON_PIN: ");
+    SerialUSB.println(BOARD_BUTTON_PIN);
+
+    SerialUSB.print("* GPIO information (BOARD_NR_GPIO_PINS = ");
+    SerialUSB.print(BOARD_NR_GPIO_PINS);
+    SerialUSB.println("):");
+    print_board_array("ADC pins", boardADCPins, BOARD_NR_ADC_PINS);
+    print_board_array("PWM pins", boardPWMPins, BOARD_NR_PWM_PINS);
+    print_board_array("Used pins", boardUsedPins, BOARD_NR_USED_PINS);
+}
+
+// -- Helper functions --------------------------------------------------------
+
+void measure_adc_noise(uint8 pin) {
+    const int N = 1000;
+    uint16 x;
+    float mean = 0;
+    float delta = 0;
+    float M2 = 0;
+    pinMode(pin, INPUT_ANALOG);
+
+    // Variance algorithm from Welford, via Knuth, by way of Wikipedia:
+    // http://en.wikipedia.org/wiki/Algorithms_for_calculating_variance#On-line_algorithm
+    for (int sample = 0; sample < N_ADC_NOISE_MEASUREMENTS; sample++) {
+        for (int i = 1; i <= N; i++) {
+            x = analogRead(pin);
+            delta = x - mean;
+            mean += delta / i;
+            M2 = M2 + delta * (x - mean);
+        }
+        SerialUSB.print("header: D");
+        SerialUSB.print(pin, DEC);
+        SerialUSB.print("\tn: ");
+        SerialUSB.print(N, DEC);
+        SerialUSB.print("\tmean: ");
+        SerialUSB.print(mean);
+        SerialUSB.print("\tvariance: ");
+        SerialUSB.println(M2 / (float)(N-1));
+    }
+
+    pinMode(pin, OUTPUT);
+}
+
+void fast_gpio(int maple_pin) {
+    gpio_dev *dev = PIN_MAP[maple_pin].gpio_device;
+    uint32 bit = PIN_MAP[maple_pin].gpio_bit;
+
+    gpio_write_bit(dev, bit, 1);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+    gpio_toggle_bit(dev, bit);
+}
+
+void serial_baud_test(HardwareSerial **serials, int n, unsigned baud) {
+    for (int i = 0; i < n; i++) {
+        serials[i]->begin(baud);
+    }
+    while (!SerialUSB.available()) {
+        for (int i = 0; i < n; i++) {
+            serials[i]->println(dummy_data);
+            if (serials[i]->available()) {
+                serials[i]->println(serials[i]->read());
+                delay(1000);
+            }
+        }
+    }
+}
+
+void serial_echo_test(HardwareSerial *serial, unsigned baud) {
+    serial->begin(baud);
+    while (!SerialUSB.available()) {
+        if (!serial->available())
+            continue;
+        serial->print(serial->read());
+    }
+}
+
+static uint16 init_all_timers_prescale = 0;
+
+static void set_prescale(timer_dev *dev) {
+    timer_set_prescaler(dev, init_all_timers_prescale);
+}
+
+void init_all_timers(uint16 prescale) {
+    init_all_timers_prescale = prescale;
+    timer_foreach(set_prescale);
+}
+
+void enable_usarts(void) {
+    Serial1.begin(BAUD);
+    Serial2.begin(BAUD);
+    Serial3.begin(BAUD);
+#if defined(STM32_HIGH_DENSITY) && !defined(BOARD_maple_RET6)
+    Serial4.begin(BAUD);
+    Serial5.begin(BAUD);
+#endif
+}
+
+void disable_usarts(void) {
+    Serial1.end();
+    Serial2.end();
+    Serial3.end();
+#if defined(STM32_HIGH_DENSITY) && !defined(BOARD_maple_RET6)
+    Serial4.end();
+    Serial5.end();
+#endif
+}
+
+void print_board_array(const char* msg, const uint8 arr[], int len) {
+    SerialUSB.print("\t");
+    SerialUSB.print(msg);
+    SerialUSB.print(" (");
+    SerialUSB.print(len);
+    SerialUSB.print("): ");
+    for (int i = 0; i < len; i++) {
+        SerialUSB.print(arr[i], DEC);
+        if (i < len - 1) SerialUSB.print(", ");
+    }
+    SerialUSB.println();
+}
+
+// -- premain() and main() ----------------------------------------------------
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated objects that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (1) {
+        loop();
+    }
+    return 0;
+}
diff --git a/tests/test-spi-roundtrip.cpp b/tests/test-spi-roundtrip.cpp
new file mode 100644
index 0000000..ddc9875
--- /dev/null
+++ b/tests/test-spi-roundtrip.cpp
@@ -0,0 +1,192 @@
+/*
+ * Polling SPI loopback test.
+ *
+ * Bob is nowhere to be found, so Alice decides to talk to herself.
+ *
+ * Instructions: Connect SPI2 (Alice) to herself (i.e., MISO to MOSI).
+ * Connect to Alice via SerialUSB.  Press any key to start.
+ *
+ * Alice will talk to herself for a little while.  The sketch will
+ * report if Alice can't hear anything she says.  She'll then start
+ * talking forever at various frequencies, bit orders, and modes.  Use
+ * an oscilloscope to make sure she's not trying to lie about any of
+ * those things.
+ *
+ * This file is released into the public domain.
+ *
+ * Author: Marti Bolivar <mbolivar@leaflabs.com>
+ */
+
+#include <wirish/wirish.h>
+
+HardwareSPI alice(2);
+
+#define NFREQS 8
+const SPIFrequency spi_freqs[] = {
+    SPI_140_625KHZ,
+    SPI_281_250KHZ,
+    SPI_562_500KHZ,
+    SPI_1_125MHZ,
+    SPI_2_25MHZ,
+    SPI_4_5MHZ,
+    SPI_9MHZ,
+    SPI_18MHZ,
+};
+
+#define TEST_BUF_SIZE 10
+uint8 test_buf[TEST_BUF_SIZE] = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9};
+
+void bad_assert(const char* file, int line, const char* exp) {
+    SerialUSB.println();
+    SerialUSB.print("ERROR: FAILED ASSERT(");
+    SerialUSB.print(exp);
+    SerialUSB.print("): ");
+    SerialUSB.print(file);
+    SerialUSB.print(": ");
+    SerialUSB.println(line);
+    throb();
+}
+
+#undef ASSERT
+#define ASSERT(exp)                                    \
+    if (exp) {                                         \
+    } else {                                           \
+        bad_assert(__FILE__, __LINE__, #exp);          \
+    }
+
+void haveConversation(uint32 bitOrder);
+void soliloquies(uint32 bitOrder);
+
+void setup() {
+    pinMode(BOARD_LED_PIN, OUTPUT);
+    SerialUSB.read();
+}
+
+void loop() {
+    SerialUSB.println("** Having a conversation, MSB first");
+    haveConversation(MSBFIRST);
+
+    SerialUSB.println("** Having a conversation, LSB first");
+    haveConversation(LSBFIRST);
+
+    SerialUSB.println();
+    SerialUSB.println("*** All done!  It looks like everything worked.");
+    SerialUSB.println();
+
+    SerialUSB.println("** Alice will now wax eloquent in various styles. "
+                      "Press any key for the next configuration.");
+    soliloquies(MSBFIRST);
+    soliloquies(LSBFIRST);
+
+    while (true)
+        ;
+}
+
+void printFrequencyString(SPIFrequency frequency);
+void chat(SPIFrequency frequency, uint32 bitOrder, uint32 mode);
+
+void haveConversation(uint32 bitOrder) {
+    for (int f = 0; f < NFREQS; f++) {
+        for (int mode = 0; mode < 4; mode++) {
+            chat(spi_freqs[f], bitOrder, mode);
+            delay(10);
+        }
+    }
+}
+
+void chat(SPIFrequency frequency, uint32 bitOrder, uint32 mode) {
+    SerialUSB.print("Having a chat.\tFrequency: ");
+    printFrequencyString(frequency);
+    SerialUSB.print(",\tbitOrder: ");
+    SerialUSB.print(bitOrder == MSBFIRST ? "MSB" : "LSB");
+    SerialUSB.print(",\tmode: ");
+    SerialUSB.print(mode);
+    SerialUSB.print(".");
+
+    SerialUSB.print(" [1] ");
+    alice.begin(frequency, bitOrder, mode);
+
+    SerialUSB.print(" [2] ");
+    uint32 txed = 0;
+    while (txed < TEST_BUF_SIZE) {
+        ASSERT(alice.transfer(test_buf[txed]) == test_buf[txed]);
+        txed++;
+    }
+
+    SerialUSB.print(" [3] ");
+    alice.end();
+
+    SerialUSB.println(" ok.");
+}
+
+void soliloquy(SPIFrequency freq, uint32 bitOrder, uint32 mode);
+
+void soliloquies(uint32 bitOrder) {
+    for (int f = 0; f < NFREQS; f++) {
+        for (int mode = 0; mode < 4; mode++) {
+            soliloquy(spi_freqs[f], bitOrder, mode);
+        }
+    }
+}
+
+void soliloquy(SPIFrequency frequency, uint32 bitOrder, uint32 mode) {
+    const uint8 repeat = 0xAE;
+    SerialUSB.print("Alice is giving a soliloquy (repeating 0x");
+    SerialUSB.print(repeat, HEX);
+    SerialUSB.print("). Frequency: ");
+    printFrequencyString(frequency);
+    SerialUSB.print(", bitOrder: ");
+    SerialUSB.print(bitOrder == MSBFIRST ? "big-endian" : "little-endian");
+    SerialUSB.print(", SPI mode: ");
+    SerialUSB.println(mode);
+
+    alice.begin(frequency, bitOrder, mode);
+    while (!SerialUSB.available()) {
+        alice.write(repeat);
+        delayMicroseconds(200);
+    }
+    SerialUSB.read();
+}
+
+void printFrequencyString(SPIFrequency frequency) {
+    switch (frequency) {
+    case SPI_18MHZ:
+        SerialUSB.print("18 MHz");
+        break;
+    case SPI_9MHZ:
+        SerialUSB.print("9 MHz");
+        break;
+    case SPI_4_5MHZ:
+        SerialUSB.print("4.5 MHz");
+        break;
+    case SPI_2_25MHZ:
+        SerialUSB.print("2.25 MHZ");
+        break;
+    case SPI_1_125MHZ:
+        SerialUSB.print("1.125 MHz");
+        break;
+    case SPI_562_500KHZ:
+        SerialUSB.print("562.500 KHz");
+        break;
+    case SPI_281_250KHZ:
+        SerialUSB.print("281.250 KHz");
+        break;
+    case SPI_140_625KHZ:
+        SerialUSB.print("140.625 KHz");
+        break;
+    }
+}
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated objects that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+    while (true) {
+        loop();
+    }
+    return 0;
+}
diff --git a/tests/test-systick.cpp b/tests/test-systick.cpp
new file mode 100644
index 0000000..356f302
--- /dev/null
+++ b/tests/test-systick.cpp
@@ -0,0 +1,49 @@
+// Tests the SysTick enable/disable functions
+
+#include <wirish/wirish.h>
+#include <libmaple/systick.h>
+
+void setup() {
+    pinMode(BOARD_LED_PIN, OUTPUT);
+    pinMode(BOARD_BUTTON_PIN, INPUT);
+}
+
+bool disable = true;
+long time = 0;
+
+void loop() {
+    volatile int i = 0;
+    toggleLED();
+
+    // An artificial delay
+    for(i = 0; i < 150000; i++)
+        ;
+
+    if (isButtonPressed()) {
+        if (disable) {
+            systick_disable();
+            SerialUSB.println("Disabling SysTick");
+        } else {
+            SerialUSB.println("Re-enabling SysTick");
+            systick_enable();
+        }
+        disable = !disable;
+    }
+
+    SerialUSB.println(millis());
+}
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated object that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}
diff --git a/tests/test-timers.cpp b/tests/test-timers.cpp
new file mode 100644
index 0000000..e646916
--- /dev/null
+++ b/tests/test-timers.cpp
@@ -0,0 +1,537 @@
+//
+// This is a mostly Wirish-free timer test. Wirish usage is minimized
+// because this is a test of the C timer interface in
+// <libmaple/timer.h>, so it's good if it can be made to work even
+// when most or all of Wirish is missing. Because of that, you may
+// need to customize the following output configuration:
+//
+// Output is printed:
+// - on COMM_USART,
+// - via TX pin on port COMM_USART_PORT, bit COMM_USART_TX_BIT
+// - via RX pin on port COMM_USART_PORT, bit COMM_USART_RX_BIT
+// - at COMM_USART_BAUD baud.
+#define COMM_USART USART6
+#define COMM_USART_BAUD 115200
+#define COMM_USART_PORT GPIOG
+#define COMM_USART_TX_BIT 14
+#define COMM_USART_RX_BIT 9
+// Other optional configuration below.
+
+#include <libmaple/libmaple.h>
+#include <libmaple/gpio.h>
+#include <libmaple/usart.h>
+#include <libmaple/systick.h>
+#include <libmaple/timer.h>
+#include <wirish/boards.h>
+
+//
+// Configuration
+//
+
+// More output if true
+static bool verbose = true;
+
+// Timers to test
+// FIXME use feature test macros for smaller MCUs
+static timer_dev *timers[] = {
+    // Available on all currently supported MCUs
+    TIMER1, TIMER2, TIMER3, TIMER4,
+    // Available on F1 (HD and up), F2
+    TIMER5, TIMER6, TIMER7, TIMER8,
+    // Available on F1 (XL), F2
+    TIMER9, TIMER10, TIMER11, TIMER12, TIMER13, TIMER14,
+};
+
+//
+// Test routines
+//
+
+typedef void (*timer_test_t)(timer_dev *);
+
+static void runTest(const char description[], timer_test_t test);
+static void runTests(void);
+
+static void testGetAndSetCount(timer_dev*);
+static void testPauseAndResume(timer_dev*);
+static void testTimerChannels(timer_dev*);
+
+//
+// Helpers
+//
+
+static void initTimer(timer_dev *dev);
+static int timerNumber(timer_dev *dev);
+// Hack: a systick-based delay, useful until delay_us() is fixed
+static void _delay(uint32 msec);
+// Wirish-less USART initialization routine
+static void init_usart(usart_dev *dev, gpio_dev *gdev, uint8 tx, uint8 rx);
+// Return whether or not the timer has capture/compare channel `ch'.
+// TODO: does something like this belong in the standard timer library?
+static bool timer_has_cc_ch(timer_dev *dev, int ch);
+
+// Printing routines and variants for verbose mode
+static void putstr(const char str[]);
+static void println(void);
+static void putstrln(const char str[]);
+static void putudec(uint32 val);
+static void puttimn(timer_dev *dev);
+static void v_putstr(const char str[]);
+static void v_println();
+static void v_putstrln(const char str[]);
+static void v_putudec(uint32 val);
+static void v_puttimn(timer_dev *dev);
+// Used to visually separate output from different tests
+static void printBanner(void);
+
+//
+// Handler state
+//
+
+static int count1 = 0;
+static int count2 = 0;
+static int count3 = 0;
+static int count4 = 0;
+static int timer_num; // Current timer we're considering
+
+//
+// Timer capture/compare interrupt handlers
+//
+// These are shared between timers. The global variable timer_num
+// controls which timer they affect.
+//
+
+static void handler1(void);
+static void handler2(void);
+static void handler3(void);
+static void handler4(void);
+static voidFuncPtr handlers[] = {handler1, handler2, handler3, handler4};
+
+//
+// setup() and loop()
+//
+
+void setup() {
+    init_usart(COMM_USART, COMM_USART_PORT,
+               COMM_USART_TX_BIT, COMM_USART_RX_BIT);
+    _delay(5);
+    println();
+    printBanner();
+    putstr("Initializing timers...\r\n");
+    timer_foreach(initTimer);
+    putstr("Done. Running tests.\r\n");
+    runTests();
+    printBanner();
+    putstr("Done testing timers.\r\n");
+}
+
+void loop() {
+}
+
+//
+// Test routine implementations
+//
+
+static void runTests(void) {
+    runTest("timer_get_count()/timer_set_count()", testGetAndSetCount);
+    runTest("timer_pause()/timer_resume()", testPauseAndResume);
+    runTest("capture/compare channels and interrupts",
+            testTimerChannels);
+}
+
+static void runTest(const char description[], timer_test_t test) {
+    printBanner();
+    putstr("Testing ");
+    putstr(description);
+    putstrln(".");
+    timer_foreach(test);
+}
+
+static void testGetAndSetCount(timer_dev *dev) {
+    unsigned before, after;
+    unsigned val_to_set = 1234;
+
+    timer_pause(dev);
+    before = timer_get_count(dev);
+    timer_set_count(dev, val_to_set);
+    after = timer_get_count(dev);
+    timer_resume(dev);
+
+    if (after != val_to_set) {
+        puttimn(dev);
+        putstr(": ");
+        putstr("*** FAIL: get/set count for ");
+        puttimn(dev);
+        putstr(".");
+        putstr("Start count = ");
+        putudec(before);
+        putstr(". Count set to ");
+        putudec(val_to_set);
+        putstr(", and now count is = ");
+        putudec(after);
+        println();
+    } else if (verbose) {
+        puttimn(dev);
+        putstr(": ");
+        putstrln("[ok]");
+    }
+}
+
+// This hack works on all currently supported STM32 series, but you
+// may need to do something smarter in the future. The assertions
+// ensure that our assumptions hold for your target.
+static timer_dev *getDifferentTimerOnSameBusAs(timer_dev *dev) {
+    rcc_clk_domain dev_domain = rcc_dev_clk(dev->clk_id);
+    ASSERT(RCC_APB1 == dev_domain || RCC_APB2 == dev_domain);
+    ASSERT(rcc_dev_clk(TIMER1->clk_id) == RCC_APB2);
+    ASSERT(rcc_dev_clk(TIMER2->clk_id) == RCC_APB1);
+    ASSERT(rcc_dev_clk(TIMER8->clk_id) == RCC_APB2);
+    ASSERT(rcc_dev_clk(TIMER3->clk_id) == RCC_APB1);
+
+    if (dev->clk_id == RCC_TIMER1) {
+        return TIMER8;
+    }
+    if (dev->clk_id == RCC_TIMER2) {
+        return TIMER3;
+    }
+    return dev_domain == RCC_APB2 ? TIMER1 : TIMER2;
+}
+
+// Rough test of pause and resume.
+//
+// Approximately half the time, dev is in the "pause" state and the
+// timer doesn't increment, while another timer (`base_dev') on the
+// same bus continues. dev and base_dev have identical start counts
+// and prescalers.
+//
+// Since dev and base_dev share a bus (and thus a base clock), and we
+// configure them to have the same prescaler and start count, the
+// ratio of their end counts should be approximately 1 : 2. We check
+// to make sure this is true, up to tolerance `epsilon'.
+static void testPauseAndResume(timer_dev *dev) {
+    timer_dev *base_dev = getDifferentTimerOnSameBusAs(dev);
+    unsigned start_count = 0, reload = 65535;
+    // This prescaler should be enough to ensure that we don't
+    // overflow, while still giving us a reasonably large number of
+    // timer ticks.
+    uint16 prescaler = CYCLES_PER_MICROSECOND * 50;
+    double epsilon = .02;
+
+    if (rcc_dev_clk(base_dev->clk_id) != rcc_dev_clk(dev->clk_id)) {
+        putstrln("*** ERROR: cannot run test. Bus info is messed up.");
+        return;
+    }
+
+    // Pause and set up timers
+    timer_pause(base_dev);
+    timer_pause(dev);
+    timer_set_count(base_dev, start_count);
+    timer_set_count(dev, start_count);
+    timer_set_reload(base_dev, reload);
+    timer_set_reload(dev, reload);
+    timer_set_prescaler(base_dev, prescaler);
+    timer_set_prescaler(dev, prescaler);
+    timer_generate_update(base_dev);
+    timer_generate_update(dev);
+
+    // Resume the timers and run the test
+    ASSERT(timer_get_count(base_dev) == start_count);
+    ASSERT(timer_get_count(dev) == start_count);
+    timer_resume(base_dev);
+    timer_resume(dev);
+    _delay(1000);
+    timer_pause(dev);
+    _delay(1000);
+    timer_pause(base_dev);
+
+    // Check the results
+    unsigned dev_count = timer_get_count(dev);
+    unsigned base_count = timer_get_count(base_dev);
+    double count_ratio = ((double)dev_count / base_count);
+    bool fail = false;
+    if (count_ratio > 0.5 + epsilon || count_ratio < 0.5 - epsilon) {
+        fail = true;
+    }
+    if (fail || verbose) {
+        puttimn(dev);
+        putstr(" vs. ");
+        puttimn(base_dev);
+        putstr(": ");
+        if (fail) putstr("*** FAIL: ");
+        else putstr("[ok] ");
+        putstr("(dev = ");
+        putudec(dev_count);
+        putstr(") / (base = ");
+        putudec(base_count);
+        putstr(") = ");
+        // hack hack hack
+        putudec((int)count_ratio);
+        count_ratio -= (int)count_ratio;
+        putstr(".");
+        int cr_x_100 = (int)(count_ratio * 100);
+        int hundredths = cr_x_100 % 10;
+        cr_x_100 /= 10;
+        int tenths = cr_x_100 % 10;
+        putudec(tenths);
+        putudec(hundredths);
+        println();
+    }
+}
+
+// This function touches every capture/compare channel of a given
+// timer.  The channel counts should be equal within a timer
+// regardless of other interrupts on the system (note that this
+// doesn't really test timers with only a single capture/compare
+// channel; for that, you'll want to do visual inspection of timers
+// that share a bus, in verbose mode).
+static void testTimerChannels(timer_dev *dev) {
+    switch (dev->type) {
+    case TIMER_BASIC:
+        v_putstr("Skipping basic timer ");
+        v_puttimn(dev);
+        v_println();
+        return;
+    case TIMER_ADVANCED:
+    case TIMER_GENERAL:
+        // Set up
+        v_puttimn(dev);
+        v_println();
+        v_putstr("\tchannels: ");
+
+        timer_num = timerNumber(dev);
+        timer_pause(dev);
+        count1 = 0;
+        count2 = 0;
+        count3 = 0;
+        count4 = 0;
+        timer_set_reload(dev, 0xFFFF);
+        timer_set_prescaler(dev, 1);
+        for (int c = 1; c <= 4; c++) {
+            if (timer_has_cc_ch(dev, c)) {
+                v_putudec(c);
+                v_putstr("\t");
+                timer_set_compare(dev, c, 0xFFFF);
+                timer_set_mode(dev, c, TIMER_OUTPUT_COMPARE);
+                timer_attach_interrupt(dev, c, handlers[c - 1]);
+            }
+        }
+        v_println();
+
+        // Run test
+        timer_generate_update(dev);
+        timer_resume(dev);
+        _delay(250);
+        timer_pause(dev);
+
+        // Print results
+        v_putstr("\tcounts:   ");
+        bool fail = false;
+        bool mismatched[4] = {false, false, false, false};
+        int counts[4];
+        counts[0] = count1;
+        counts[1] = count2;
+        counts[2] = count3;
+        counts[3] = count4;
+        bool first = true;
+        int first_count = -1;
+        for (int c = 1; c <= 4; c++) {
+            if (timer_has_cc_ch(dev, c)) {
+                if (first) {
+                    first_count = counts[c - 1];
+                    first = false;
+                }
+                if (!first && (counts[c - 1] != first_count)) {
+                    mismatched[c - 1] = true;
+                    fail = true;
+                }
+                v_putudec(counts[c - 1]);
+                v_putstr("\t");
+            }
+        }
+        v_println();
+        if (fail) {
+            for (int i = 0; i < 4; i++) {
+                if (mismatched[i]) {
+                    putstr("*** FAIL: mismatch on ");
+                    puttimn(dev);
+                    putstr(", channel ");
+                    putudec(i + 1);
+                    putstr(": expected ");
+                    putudec(first_count);
+                    putstr(", got ");
+                    putudec(counts[i]);
+                    println();
+                }
+            }
+        } else {
+            puttimn(dev);
+            putstrln(" [ok]");
+        }
+        v_println();
+
+        // Clean up
+        for (int c = 1; c <= 4; c++) {
+            if (timer_has_cc_ch(dev, c)) {
+                timer_set_mode(dev, c, TIMER_DISABLED);
+            }
+        }
+        break;
+    }
+}
+
+//
+// Helper implementations
+//
+
+static void _delay(uint32 msec) {
+    uint32 end = systick_uptime() + msec;
+    while (systick_uptime() < end)
+        ;
+}
+
+static void init_usart(usart_dev *dev, gpio_dev *gdev, uint8 tx, uint8 rx) {
+    usart_config_gpios_async(dev, gdev, rx, gdev, tx, 0);
+    usart_init(dev);
+    usart_set_baud_rate(dev, USART_USE_PCLK, COMM_USART_BAUD);
+    usart_enable(dev);
+}
+
+static bool timer_has_cc_ch(timer_dev *dev, int ch) {
+    ASSERT(1 <= ch && ch <= 4);
+    if (dev->type == TIMER_BASIC)
+        return false;
+    int tn = timerNumber(dev);
+    return  (// TIM1-5 and 8 have all four channels
+             (tn <= 5 || tn == 8) ||
+             // TIM9 and 12 only have channels 1 and 2
+             ((tn == 9 || tn == 12) && ch <= 2) ||
+             // All other general purpose timers only have channel 1
+             (ch == 1));
+}
+
+static void putstr(const char str[]) {
+    usart_putstr(COMM_USART, str);
+}
+
+static void println(void) {
+    putstr("\r\n");
+}
+
+static void putstrln(const char str[]) {
+    putstr(str);
+    println();
+}
+
+static void putudec(uint32 val) {
+    usart_putudec(COMM_USART, val);
+}
+
+static void puttimn(timer_dev *dev) {
+    putstr("TIM");
+    putudec(timerNumber(dev));
+}
+
+static void v_putstr(const char str[]) {
+    if (verbose) putstr(str);
+}
+
+static void v_println() {
+    if (verbose) println();
+}
+
+__attribute__((unused)) /* (shut up, gcc) */
+static void v_putstrln(const char str[]) {
+    if (verbose) putstrln(str);
+}
+
+static void v_putudec(uint32 val) {
+    if (verbose) putudec(val);
+}
+
+static void v_puttimn(timer_dev *dev) {
+    if (verbose) puttimn(dev);
+}
+
+// Used to visually separate output from different tests
+static void printBanner(void) {
+    putstrln("-----------------------------------------------------");
+}
+
+static void initTimer(timer_dev *dev) {
+    v_puttimn(dev);
+    timer_init(dev);
+    switch (dev->type) {
+    case TIMER_ADVANCED:
+    case TIMER_GENERAL:
+        v_putstr(" channels ");
+        for (int c = 1; c <= 4; c++) {
+            if (timer_has_cc_ch(dev, c)) {
+                v_putudec(c);
+                v_putstr(" ");
+                timer_set_mode(dev, c, TIMER_OUTPUT_COMPARE);
+            }
+        }
+        break;
+    case TIMER_BASIC:
+        break;
+    }
+    v_println();
+}
+
+static int timerNumber(timer_dev *dev) {
+    switch (dev->clk_id) {
+    case RCC_TIMER1: return 1;
+    case RCC_TIMER2: return 2;
+    case RCC_TIMER3: return 3;
+    case RCC_TIMER4: return 4;
+    case RCC_TIMER5: return 5;
+    case RCC_TIMER6: return 6;
+    case RCC_TIMER7: return 7;
+    case RCC_TIMER8: return 8;
+    case RCC_TIMER9: return 9;
+    case RCC_TIMER10: return 10;
+    case RCC_TIMER11: return 11;
+    case RCC_TIMER12: return 12;
+    case RCC_TIMER13: return 13;
+    case RCC_TIMER14: return 14;
+    default:
+        ASSERT(0);
+        return 0;
+    }
+}
+
+//
+// IRQ Handlers
+//
+
+static void handler1(void) {
+    count1++;
+}
+
+static void handler2(void) {
+    count2++;
+}
+
+static void handler3(void) {
+    count3++;
+}
+
+static void handler4(void) {
+    count4++;
+}
+
+//
+// init() and main()
+//
+
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}
diff --git a/tests/test-usart-dma.cpp b/tests/test-usart-dma.cpp
new file mode 100644
index 0000000..7d6d8b9
--- /dev/null
+++ b/tests/test-usart-dma.cpp
@@ -0,0 +1,211 @@
+/**
+ * @file tests/test-usart-dma.cpp
+ * @author Marti Bolivar <mbolivar@leaflabs.com>
+ *
+ * Simple test of DMA used with a USART receiver.
+ *
+ * Configures a USART receiver for use with DMA.  Received bytes are
+ * placed into a buffer, with an interrupt firing when the buffer is
+ * full.  At that point, the USART transmitter will print the contents
+ * of the byte buffer.  The buffer is continually filled and refilled
+ * in this manner.
+ *
+ * This example isn't very robust; don't use it in production.  In
+ * particular, since the buffer keeps filling (DMA_CIRC_MODE is set),
+ * if you keep sending characters after filling the buffer, you'll
+ * overwrite earlier bytes; this may happen before those earlier bytes
+ * are done printing. (Typing quickly and seeing how it affects the
+ * output is a fun way to make sense of how the interrupts and the
+ * main thread of execution interleave.)
+ *
+ * This code is released into the public domain.
+ */
+
+#include <libmaple/dma.h>
+#include <libmaple/usart.h>
+#include <libmaple/gpio.h>
+
+#include <wirish/wirish.h>
+
+/*
+ * Configuration and state
+ */
+
+// Serial port and DMA configuration. You can change these to suit
+// your purposes.
+HardwareSerial *serial = &Serial2;
+#define USART_DMA_DEV DMA1
+#if STM32_MCU_SERIES == STM32_SERIES_F1
+// On STM32F1 microcontrollers (like what's on Maple and Maple Mini),
+// dma tubes are channels.
+#define USART_RX_DMA_TUBE DMA_CH6
+#elif (STM32_MCU_SERIES == STM32_SERIES_F2 || \
+       STM32_MCU_SERIES == STM32_SERIES_F4)
+// On STM32F2 and STM32F4 microcontrollers (Maple 2 will have an F4),
+// dma tubes are streams.
+#define USART_RX_DMA_TUBE DMA_S5
+#else
+#error "unsupported stm32 series"
+#endif
+// The serial port will make a DMA request each time it receives data.
+// This is the dma_request_src we use to tell the DMA tube to handle
+// that DMA request.
+#define USART_DMA_REQ_SRC DMA_REQ_SRC_USART2_RX
+#define BAUD 9600
+
+// This will store the DMA configuration for USART RX.
+dma_tube_config tube_config;
+
+// This will store received USART characters.
+#define BUF_SIZE 20
+char rx_buf[BUF_SIZE];
+
+// The interrupt handler, rx_dma_irq(), sets this to 1.
+volatile uint32 irq_fired = 0;
+// Used to store DMA interrupt status register (ISR) bits inside
+// rx_dma_irq(). This helps explain what's going on inside loop(); see
+// comments below.
+volatile uint32 isr = 0;
+
+/*
+ * Helper functions
+ */
+
+// This is our DMA interrupt handler.
+void rx_dma_irq(void) {
+    irq_fired = 1;
+    isr = dma_get_isr_bits(USART_DMA_DEV, USART_RX_DMA_TUBE);
+}
+
+// Configure the USART receiver for use with DMA:
+// 1. Turn it on.
+// 2. Set the "DMA request on RX" bit in USART_CR3 (USART_CR3_DMAR).
+void setup_usart(void) {
+    serial->begin(BAUD);
+    usart_dev *serial_dev = serial->c_dev();
+    serial_dev->regs->CR3 = USART_CR3_DMAR;
+}
+
+// Set up our dma_tube_config structure. (We could have done this
+// above, when we declared tube_config, but having this function makes
+// it easier to explain what's going on).
+void setup_tube_config(void) {
+    // We're receiving from the USART data register. serial->c_dev()
+    // returns a pointer to the libmaple usart_dev for that serial
+    // port, so this is a pointer to its data register.
+    tube_config.tube_src = &serial->c_dev()->regs->DR;
+    // We're only interested in the bottom 8 bits of that data register.
+    tube_config.tube_src_size = DMA_SIZE_8BITS;
+    // We're storing to rx_buf.
+    tube_config.tube_dst = rx_buf;
+    // rx_buf is a char array, and a "char" takes up 8 bits on STM32.
+    tube_config.tube_dst_size = DMA_SIZE_8BITS;
+    // Only fill BUF_SIZE - 1 characters, to leave a null byte at the end.
+    tube_config.tube_nr_xfers = BUF_SIZE - 1;
+    // Flags:
+    // - DMA_CFG_DST_INC so we start at the beginning of rx_buf and
+    //   fill towards the end.
+    // - DMA_CFG_CIRC so we go back to the beginning and start over when
+    //   rx_buf fills up.
+    // - DMA_CFG_CMPLT_IE to turn on interrupts on transfer completion.
+    tube_config.tube_flags = DMA_CFG_DST_INC | DMA_CFG_CIRC | DMA_CFG_CMPLT_IE;
+    // Target data: none. It's important to set this to NULL if you
+    // don't have any special (microcontroller-specific) configuration
+    // in mind, which we don't.
+    tube_config.target_data = NULL;
+    // DMA request source.
+    tube_config.tube_req_src = USART_DMA_REQ_SRC;
+}
+
+// Configure the DMA controller to serve DMA requests from the USART.
+void setup_dma_xfer(void) {
+    // First, turn it on.
+    dma_init(USART_DMA_DEV);
+    // Next, configure it by calling dma_tube_cfg(), and check to make
+    // sure it succeeded. DMA tubes have many restrictions on their
+    // configuration, and there are configurations which work on some
+    // types of STM32 but not others. libmaple tries hard to make
+    // things just work, but checking the return status is important!
+    int status = dma_tube_cfg(USART_DMA_DEV, USART_RX_DMA_TUBE, &tube_config);
+    ASSERT(status == DMA_TUBE_CFG_SUCCESS);
+    // Now we'll perform any other configuration we want. For this
+    // example, we attach an interrupt handler.
+    dma_attach_interrupt(USART_DMA_DEV, USART_RX_DMA_TUBE, rx_dma_irq);
+    // Turn on the DMA tube. It will now begin serving requests.
+    dma_enable(USART_DMA_DEV, USART_RX_DMA_TUBE);
+}
+
+/*
+ * setup() and loop()
+ */
+
+void setup(void) {
+    pinMode(BOARD_LED_PIN, OUTPUT);
+    setup_tube_config();
+    setup_dma_xfer();
+    setup_usart();
+}
+
+void loop(void) {
+    toggleLED();
+    delay(100);
+
+    // See if the interrupt handler got called since the last time we
+    // checked.
+    if (irq_fired) {
+        serial->println("** IRQ **");
+        // Notice how the interrupt status register (ISR) bits show
+        // transfer complete _and_ half-complete here, but the ISR
+        // bits we print next will be zero. That's because the
+        // variable "isr" gets set _inside_ rx_dma_irq(). After it
+        // exits, libmaple cleans up by clearing the tube's ISR
+        // bits. (If it didn't, and we forgot to, the interrupt would
+        // repeatedly fire forever.)
+        serial->print("ISR bits: 0x");
+        serial->println(isr, HEX);
+        irq_fired = 0;
+    }
+
+    // Print the ISR bits.
+    //
+    // Notice that the "transfer half-complete" ISR flag gets set when
+    // we reach the rx_buf half-way point. This is true even though we
+    // don't tell the DMA controller to interrupt us on a
+    // half-complete transfer. That is, the ISR bits get set at the
+    // right times no matter what; we just don't get interrupted
+    // unless we asked. (If an error or other problem occurs, the
+    // relevant ISR bits will get set in the same way).
+    serial->print("[");
+    serial->print(millis());
+    serial->print("]\tISR bits: 0x");
+    uint8 isr_bits = dma_get_isr_bits(USART_DMA_DEV, USART_RX_DMA_TUBE);
+    serial->print(isr_bits, HEX);
+
+    // Print the contents of rx_buf. If you keep typing after it fills
+    // up, the new characters will overwrite the old ones, thanks to
+    // DMA_CIRC_MODE.
+    serial->print("\tCharacter buffer contents: '");
+    serial->print(rx_buf);
+    serial->println("'");
+    if (isr_bits == 0x7) {
+        serial->println("** Clearing ISR bits.");
+        dma_clear_isr_bits(USART_DMA_DEV, USART_RX_DMA_TUBE);
+    }
+}
+
+// ------- init() and main() --------------------------------------------------
+
+// Force init to be called *first*, i.e. before static object allocation.
+// Otherwise, statically allocated objects that need libmaple may fail.
+__attribute__((constructor)) void premain() {
+    init();
+}
+
+int main(void) {
+    setup();
+
+    while (true) {
+        loop();
+    }
+    return 0;
+}