external interrupt refactor: allow enabling in watch library functions

8 files changed, 233 insertions, 128 deletions

diff --git a/Sensor Watch Starter Project/app.c b/Sensor Watch Starter Project/app.c
index 87326422..3fa3a618 100644
--- a/Sensor Watch Starter Project/app.c
+++ b/Sensor Watch Starter Project/app.c
@@ -11,17 +11,16 @@ typedef enum ApplicationMode {
 } ApplicationMode;
 
 typedef enum LightColor {
-    COLOR_OFF = 0,
-    COLOR_RED = 1,
-    COLOR_GREEN = 2,
-    COLOR_YELLOW = 3
+    COLOR_RED = 0,
+    COLOR_GREEN,
+    COLOR_YELLOW
 } LightColor;
 
 typedef struct ApplicationState {
     ApplicationMode mode;
     LightColor color;
+    bool light_on;
     uint8_t wake_count;
-    bool debounce_wait;
     bool enter_deep_sleep;
 } ApplicationState;
 
@@ -62,7 +61,6 @@ void app_wake_from_deep_sleep() {
     application_state.mode = (ApplicationMode)watch_get_backup_data(0);
     application_state.color = (LightColor)watch_get_backup_data(1);
     application_state.wake_count = (uint8_t)watch_get_backup_data(2) + 1;
-    application_state.debounce_wait = true;
 }
 
 /**
@@ -80,10 +78,18 @@ void app_wake_from_deep_sleep() {
 void app_setup() {
     watch_enable_led(false); // enable LED with plain digital IO, not PWM
 
-    watch_enable_buttons();
-    watch_register_button_callback(BTN_LIGHT, cb_light_pressed);
-    watch_register_button_callback(BTN_MODE, cb_mode_pressed);
-    watch_register_button_callback(BTN_ALARM, cb_alarm_pressed);
+    watch_enable_external_interrupts();
+    // This starter app demonstrates three different ways of using the button interrupts.
+    // The BTN_MODE interrupt only triggers on a rising edge, so the mode changes once per press.
+    watch_register_interrupt_callback(BTN_MODE, cb_mode_pressed, INTERRUPT_TRIGGER_RISING);
+    // The BTN_LIGHT interrupt triggers on both rising and falling edges. The callback then checks
+    // the pin state when triggered: on a button down event, it increments the color and turns the
+    // LED on, whereas on a button up event, it turns the light off.
+    watch_register_interrupt_callback(BTN_LIGHT, cb_light_pressed, INTERRUPT_TRIGGER_BOTH);
+    // The BTN_ALARM callback is on an external wake pin; we can avoid using the EIC for this pin
+    // by using the extwake interrupt — but note that it can only trigger on either a rising or
+    // a falling edge, not both.
+    watch_register_extwake_callback(BTN_ALARM, cb_alarm_pressed, true);
 
     watch_enable_display();
 }
@@ -95,7 +101,6 @@ void app_setup() {
  * a press on one of the buttons).
  */
 void app_prepare_for_sleep() {
-    application_state.debounce_wait = false;
 }
 
 /**
@@ -112,19 +117,20 @@ void app_wake_from_sleep() {
  */
 bool app_loop() {
     // set the LED to a color
-    switch (application_state.color) {
-        case COLOR_OFF:
-            watch_set_led_off();
-            break;
-        case COLOR_RED:
-            watch_set_led_red();
-            break;
-        case COLOR_GREEN:
-            watch_set_led_green();
-            break;
-        case COLOR_YELLOW:
-            watch_set_led_yellow();
-            break;
+    if (application_state.light_on) {
+        switch (application_state.color) {
+            case COLOR_RED:
+                watch_set_led_red();
+                break;
+            case COLOR_GREEN:
+                watch_set_led_green();
+                break;
+            case COLOR_YELLOW:
+                watch_set_led_yellow();
+                break;
+        }
+    } else {
+        watch_set_led_off();
     }
 
     // Display the number of times we've woken up (modulo 32 to fit in 2 digits at top right)
@@ -142,9 +148,6 @@ bool app_loop() {
             break;
     }
 
-    // Wait a moment to debounce button input
-    delay_ms(250);
-
     if (application_state.enter_deep_sleep) {
         application_state.enter_deep_sleep = false;
 
@@ -171,20 +174,20 @@ bool app_loop() {
 // Implementations for our callback functions. Replace these with whatever functionality
 // your app requires.
 void cb_light_pressed() {
-    if (application_state.debounce_wait) return;
-    application_state.debounce_wait = true;
-    application_state.color = (application_state.color + 1) % 4;
+    // always turn the light off when the pin goes low
+    if (watch_get_pin_level(BTN_LIGHT) == 0) {
+        application_state.light_on = false;
+        return;
+    }
+    application_state.color = (application_state.color + 1) % 3;
+    application_state.light_on = true;
 }
 
 void cb_mode_pressed() {
-    if (application_state.debounce_wait) return;
-    application_state.debounce_wait = true;
     application_state.mode = (application_state.mode + 1) % 2;
 }
 
 void cb_alarm_pressed() {
-    if (application_state.debounce_wait) return;
-    application_state.debounce_wait = true;
     // boo: http://ww1.microchip.com/downloads/en/DeviceDoc/SAM_L22_Family_Errata_DS80000782B.pdf
     // Reference 15010. doesn't say it applies to PA02 but it seems it does?
     // anyway can't deep sleep now :(
diff --git a/watch-library/hw/driver_init.c b/watch-library/hw/driver_init.c
index 02907feb..6d910d22 100644
--- a/watch-library/hw/driver_init.c
+++ b/watch-library/hw/driver_init.c
@@ -35,52 +35,6 @@ void ADC_0_init(void) {
 	adc_sync_init(&ADC_0, ADC, (void *)NULL);
 }
 
-void EXTERNAL_IRQ_0_init(void) {
-	hri_gclk_write_PCHCTRL_reg(GCLK, EIC_GCLK_ID, CONF_GCLK_EIC_SRC | (1 << GCLK_PCHCTRL_CHEN_Pos));
-	hri_mclk_set_APBAMASK_EIC_bit(MCLK);
-
-	// Set pin direction to input
-	gpio_set_pin_direction(BTN_ALARM, GPIO_DIRECTION_IN);
-
-	gpio_set_pin_pull_mode(BTN_ALARM,
-	                       // <y> Pull configuration
-	                       // <id> pad_pull_config
-	                       // <GPIO_PULL_OFF"> Off
-	                       // <GPIO_PULL_UP"> Pull-up
-	                       // <GPIO_PULL_DOWN"> Pull-down
-	                       GPIO_PULL_DOWN);
-
-	gpio_set_pin_function(BTN_ALARM, PINMUX_PA02A_EIC_EXTINT2);
-
-	// Set pin direction to input
-	gpio_set_pin_direction(BTN_LIGHT, GPIO_DIRECTION_IN);
-
-	gpio_set_pin_pull_mode(BTN_LIGHT,
-	                       // <y> Pull configuration
-	                       // <id> pad_pull_config
-	                       // <GPIO_PULL_OFF"> Off
-	                       // <GPIO_PULL_UP"> Pull-up
-	                       // <GPIO_PULL_DOWN"> Pull-down
-	                       GPIO_PULL_DOWN);
-
-	gpio_set_pin_function(BTN_LIGHT, PINMUX_PA22A_EIC_EXTINT6);
-
-	// Set pin direction to input
-	gpio_set_pin_direction(BTN_MODE, GPIO_DIRECTION_IN);
-
-	gpio_set_pin_pull_mode(BTN_MODE,
-	                       // <y> Pull configuration
-	                       // <id> pad_pull_config
-	                       // <GPIO_PULL_OFF"> Off
-	                       // <GPIO_PULL_UP"> Pull-up
-	                       // <GPIO_PULL_DOWN"> Pull-down
-	                       GPIO_PULL_DOWN);
-
-	gpio_set_pin_function(BTN_MODE, PINMUX_PA23A_EIC_EXTINT7);
-
-	ext_irq_init();
-}
-
 void CALENDAR_0_CLOCK_init(void) {
 	hri_mclk_set_APBAMASK_RTC_bit(MCLK);
 }
diff --git a/watch-library/watch/watch.c b/watch-library/watch/watch.c
index d55b61fe..059c2a93 100644
--- a/watch-library/watch/watch.c
+++ b/watch-library/watch/watch.c
@@ -24,11 +24,6 @@
 
 #include "watch.h"
 
-// TODO: this should all live in watch_deepsleep.c, but right now watch_extint.c needs it
-// because we're being too clever about the alarm button.
-static void extwake_callback(uint8_t reason);
-ext_irq_cb_t btn_alarm_callback;
-
 #include "watch_rtc.c"
 #include "watch_slcd.c"
 #include "watch_extint.c"
diff --git a/watch-library/watch/watch_deepsleep.c b/watch-library/watch/watch_deepsleep.c
index 53a41b5c..ecc10b2b 100644
--- a/watch-library/watch/watch_deepsleep.c
+++ b/watch-library/watch/watch_deepsleep.c
@@ -22,8 +22,10 @@
  * SOFTWARE.
  */
 
+static void extwake_callback(uint8_t reason);
+ext_irq_cb_t btn_alarm_callback;
 ext_irq_cb_t a2_callback;
-ext_irq_cb_t d1_callback;
+ext_irq_cb_t a4_callback;
 
  static void extwake_callback(uint8_t reason) {
     if (reason & RTC_TAMPID_TAMPID2) {
@@ -31,23 +33,59 @@ ext_irq_cb_t d1_callback;
     } else if (reason & RTC_TAMPID_TAMPID1) {
         if (a2_callback != NULL) a2_callback();
     } else if (reason & RTC_TAMPID_TAMPID0) {
-        if (d1_callback != NULL) d1_callback();
+        if (a4_callback != NULL) a4_callback();
     }
 }
 
-void watch_register_extwake_callback(uint8_t pin, ext_irq_cb_t callback) {
+void watch_register_extwake_callback(uint8_t pin, ext_irq_cb_t callback, bool level) {
     uint32_t pinmux;
-    if (pin == D1) {
-        d1_callback = callback;
-        pinmux = PINMUX_PB00G_RTC_IN0;
-    } else if (pin == A2) {
-        a2_callback = callback;
-        pinmux = PINMUX_PB02G_RTC_IN1;
-    } else {
-        return;
+    hri_rtc_tampctrl_reg_t config = hri_rtc_get_TAMPCTRL_reg(RTC, 0xFFFFFFFF);
+
+    switch (pin) {
+        case A4:
+            a4_callback = callback;
+            pinmux = PINMUX_PB00G_RTC_IN0;
+            config &= ~(3 << RTC_TAMPCTRL_IN0ACT_Pos);
+            config &= ~(1 << RTC_TAMPCTRL_TAMLVL0_Pos);
+            config |= 1 << RTC_TAMPCTRL_IN0ACT_Pos;
+            config |= 1 << RTC_TAMPCTRL_DEBNC0_Pos;
+            if (level) config |= 1 << RTC_TAMPCTRL_TAMLVL0_Pos;
+            break;
+        case A2:
+            a2_callback = callback;
+            pinmux = PINMUX_PB02G_RTC_IN1;
+            config &= ~(3 << RTC_TAMPCTRL_IN1ACT_Pos);
+            config &= ~(1 << RTC_TAMPCTRL_TAMLVL1_Pos);
+            config |= 1 << RTC_TAMPCTRL_IN1ACT_Pos;
+            config |= 1 << RTC_TAMPCTRL_DEBNC1_Pos;
+            if (level) config |= 1 << RTC_TAMPCTRL_TAMLVL1_Pos;
+            break;
+        case BTN_ALARM:
+            gpio_set_pin_pull_mode(pin, GPIO_PULL_DOWN);
+            btn_alarm_callback = callback;
+            pinmux = PINMUX_PA02G_RTC_IN2;
+            config &= ~(3 << RTC_TAMPCTRL_IN2ACT_Pos);
+            config &= ~(1 << RTC_TAMPCTRL_TAMLVL2_Pos);
+            config |= 1 << RTC_TAMPCTRL_IN2ACT_Pos;
+            config |= 1 << RTC_TAMPCTRL_DEBNC2_Pos;
+            if (level) config |= 1 << RTC_TAMPCTRL_TAMLVL2_Pos;
+            break;
+        default:
+            return;
     }
     gpio_set_pin_direction(pin, GPIO_DIRECTION_IN);
     gpio_set_pin_function(pin, pinmux);
+
+    // disable the RTC
+	if (hri_rtcmode0_get_CTRLA_ENABLE_bit(RTC)) {
+		hri_rtcmode0_clear_CTRLA_ENABLE_bit(RTC);
+		hri_rtcmode0_wait_for_sync(RTC, RTC_MODE0_SYNCBUSY_ENABLE);
+	}
+    // update the configuration
+    hri_rtc_write_TAMPCTRL_reg(RTC, config);
+    // re-enable the RTC
+    hri_rtcmode0_set_CTRLA_ENABLE_bit(RTC);
+
     _extwake_register_callback(&CALENDAR_0.device, extwake_callback);
 }
 
@@ -67,7 +105,7 @@ uint32_t watch_get_backup_data(uint8_t reg) {
 
 void watch_enter_deep_sleep() {
     // enable and configure the external wake interrupt, if not already set up.
-    if (btn_alarm_callback == NULL && a2_callback == NULL && d1_callback == NULL) {
+    if (btn_alarm_callback == NULL && a2_callback == NULL && a4_callback == NULL) {
         gpio_set_pin_direction(BTN_ALARM, GPIO_DIRECTION_IN);
         gpio_set_pin_pull_mode(BTN_ALARM, GPIO_PULL_DOWN);
         gpio_set_pin_function(BTN_ALARM, PINMUX_PA02G_RTC_IN2);
diff --git a/watch-library/watch/watch_deepsleep.h b/watch-library/watch/watch_deepsleep.h
index cea6f1aa..14fe8115 100644
--- a/watch-library/watch/watch_deepsleep.h
+++ b/watch-library/watch/watch_deepsleep.h
@@ -28,16 +28,24 @@
   *        deepest sleep mode available on the SAM L22
   */
 /// @{
+
 /** @brief Registers a callback on one of the RTC's external wake pins, which can wake the device
-  * from deep sleep mode.
-  * @param pin Either pin A2 or pin D1, the two external wake pins on the nine-pin connector.
+  *        from deep sleep (aka BACKUP) mode.
+  * @param pin Either pin BTN_ALARM, A2, or A4. These are the three external wake pins. If the pin
+  *            is BTN_ALARM, this function also enables an internal pull down on that pin.
   * @param callback The callback to be called if this pin triggers outside of deep sleep mode.
+  * @param level The level you wish to scan for: true for rising, false for falling. Note that you
+  *              cannot scan for both rising and falling edges like you can with the external interrupt
+  *              pins; with the external wake interrupt, you can only get one or the other.
   * @note When in normal or STANDBY mode, this will function much like a standard external interrupt
   *       situation: these pins will wake from standby, and your callback will be called. However,
   *       if the device enters deep sleep and one of these pins wakes the device, your callback
-  *       WILL NOT be called.
+  *       WILL NOT be called, as the device is basically waking from reset at that point.
+  * @warning As of the current SAM L22 silicon revision (rev B), the BTN_ALARM pin cannot wake the
+  *          device from BACKUP mode. You can still use this function to register a BTN_ALARM interrupt
+  *          in normal or STANDBY mode, but to wake from BACKUP, you will need to use pin A2 or A4.
   */
-void watch_register_extwake_callback(uint8_t pin, ext_irq_cb_t callback);
+void watch_register_extwake_callback(uint8_t pin, ext_irq_cb_t callback, bool level);
 
 /** @brief Stores data in one of the RTC's backup registers, which retain their data in deep sleep.
   * @param data An unsigned 32 bit integer with the data you wish to store.
diff --git a/watch-library/watch/watch_extint.c b/watch-library/watch/watch_extint.c
index 19f6041a..421700bc 100644
--- a/watch-library/watch/watch_extint.c
+++ b/watch-library/watch/watch_extint.c
@@ -22,18 +22,96 @@
  * SOFTWARE.
  */
 
- void watch_enable_buttons() {
-    EXTERNAL_IRQ_0_init();
+void watch_enable_external_interrupts() {
+    // Configure EIC to use GCLK3 (the 32.768 kHz crystal)
+    hri_gclk_write_PCHCTRL_reg(GCLK, EIC_GCLK_ID, GCLK_PCHCTRL_GEN_GCLK3_Val | (1 << GCLK_PCHCTRL_CHEN_Pos));
+    // Enable AHB clock for the EIC
+    hri_mclk_set_APBAMASK_EIC_bit(MCLK);
+    // call HAL's external interrupt init function
+    ext_irq_init();
 }
 
-void watch_register_button_callback(const uint8_t pin, ext_irq_cb_t callback) {
-    if (pin == BTN_ALARM) {
-        gpio_set_pin_direction(BTN_ALARM, GPIO_DIRECTION_IN);
-        gpio_set_pin_pull_mode(BTN_ALARM, GPIO_PULL_DOWN);
-        gpio_set_pin_function(BTN_ALARM, PINMUX_PA02G_RTC_IN2);
-        btn_alarm_callback = callback;
-        _extwake_register_callback(&CALENDAR_0.device, extwake_callback);
-    } else {
-        ext_irq_register(pin, callback);
+void watch_disable_external_interrupts() {
+    ext_irq_deinit();
+    hri_mclk_clear_APBAMASK_EIC_bit(MCLK);
+}
+
+void watch_register_interrupt_callback(const uint8_t pin, ext_irq_cb_t callback, watch_interrupt_trigger trigger) {
+    uint32_t pinmux;
+    hri_eic_config_reg_t config = hri_eic_get_CONFIG_reg(EIC, 0, 0xFFFFFFFF);
+
+    switch (pin) {
+        case A4:
+            // same steps for each: determine the correct pin mux...
+            pinmux = PINMUX_PB00A_EIC_EXTINT0;
+            // ...clear out the configuration for this EIC channel...
+            config &= ~EIC_CONFIG_SENSE0_Msk;
+            // ...and reconfigure it with our new trigger value.
+            config |= EIC_CONFIG_SENSE0(trigger);
+            break;
+        case A1:
+            pinmux = PINMUX_PB01A_EIC_EXTINT1;
+            config &= ~EIC_CONFIG_SENSE1_Msk;
+            config |= EIC_CONFIG_SENSE1(trigger);
+            break;
+        case BTN_ALARM:
+            gpio_set_pin_pull_mode(pin, GPIO_PULL_DOWN);
+            pinmux = PINMUX_PA02A_EIC_EXTINT2;
+            config &= ~EIC_CONFIG_SENSE2_Msk;
+            config |= EIC_CONFIG_SENSE2(trigger);
+            break;
+        case A2:
+            pinmux = PINMUX_PB02A_EIC_EXTINT2;
+            config &= ~EIC_CONFIG_SENSE2_Msk;
+            config |= EIC_CONFIG_SENSE2(trigger);
+            break;
+        case A3:
+            pinmux = PINMUX_PB03A_EIC_EXTINT3;
+            config &= ~EIC_CONFIG_SENSE3_Msk;
+            config |= EIC_CONFIG_SENSE3(trigger);
+            break;
+        case A0:
+            pinmux = PINMUX_PB04A_EIC_EXTINT4;
+            config &= ~EIC_CONFIG_SENSE4_Msk;
+            config |= EIC_CONFIG_SENSE4(trigger);
+            break;
+        case BTN_LIGHT:
+            gpio_set_pin_pull_mode(pin, GPIO_PULL_DOWN);
+            pinmux = PINMUX_PA22A_EIC_EXTINT6;
+            config &= ~EIC_CONFIG_SENSE6_Msk;
+            config |= EIC_CONFIG_SENSE6(trigger);
+            break;
+        case BTN_MODE:
+            gpio_set_pin_pull_mode(pin, GPIO_PULL_DOWN);
+            pinmux = PINMUX_PA23A_EIC_EXTINT7;
+            config &= ~EIC_CONFIG_SENSE7_Msk;
+            config |= EIC_CONFIG_SENSE7(trigger);
+            break;
+        default:
+            return;
+    }
+
+    gpio_set_pin_direction(pin, GPIO_DIRECTION_IN);
+    gpio_set_pin_function(pin, pinmux);
+
+    // EIC configuration register is enable-protected, so we have to disable it first...
+    if (hri_eic_get_CTRLA_reg(EIC, EIC_CTRLA_ENABLE)) {
+        hri_eic_clear_CTRLA_ENABLE_bit(EIC);
+        // ...and wait for it to synchronize.
+        hri_eic_wait_for_sync(EIC, EIC_SYNCBUSY_ENABLE);
     }
+    // now update the configuration...
+	hri_eic_write_CONFIG_reg(EIC, 0, config);
+    // ...and re-enable the EIC
+	hri_eic_set_CTRLA_ENABLE_bit(EIC);
+
+    ext_irq_register(pin, callback);
+}
+
+inline void watch_register_button_callback(const uint8_t pin, ext_irq_cb_t callback) {
+    watch_register_interrupt_callback(pin, callback, INTERRUPT_TRIGGER_RISING);
+}
+
+inline void watch_enable_buttons() {
+    watch_enable_external_interrupts();
 }
diff --git a/watch-library/watch/watch_extint.h b/watch-library/watch/watch_extint.h
index 71295902..d1265119 100644
--- a/watch-library/watch/watch_extint.h
+++ b/watch-library/watch/watch_extint.h
@@ -25,28 +25,57 @@
 
 #include "hal_ext_irq.h"
 
-/** @addtogroup buttons Buttons
-  * @brief This section covers functions related to the three buttons: Light, Mode and Alarm.
+/** @addtogroup buttons Buttons & External Interrupts
+  * @brief This section covers functions related to the three buttons: Light, Mode and Alarm, as well as
+  *        external interrupts from devices on the nine-pin connector.
   * @details The buttons are the core input UI of the watch, and the way the user will interact with
   *          your application. They are active high, pulled down by the microcontroller, and triggered
   *          when one of the "pushers" brings a tab from the metal frame into contact with the edge
-  *          of the board. Note that the buttons can only wake the watch from STANDBY mode (except maybe for the
-  *          ALARM button; still working on that one). The external interrupt controller runs in
-             STANDBY mode, but it does not runin BACKUP mode; to wake from BACKUP, buttons will not cut it,
+  *          of the board. Note that the buttons can only wake the watch from STANDBY mode, at least as
+  *          of the current SAM L22 silicon revision. The external interrupt controller runs in STANDBY
+  *          mode, but it does not run in BACKUP mode; to wake from BACKUP, buttons will not cut it.
   */
 /// @{
-/** @brief Enables the external interrupt controller for use with the buttons.
-  * @note The BTN_ALARM button runs off of an interrupt in the the RTC controller, not the EIC. If your
-  *       application ONLY makes use of the alarm button, you do not need to call this method; you can
-  *       save ~5µA by leaving the EIC disabled and only registering a callback for BTN_ALARM.
-  */
-void watch_enable_buttons();
 
-/** @brief Configures an external interrupt on one of the button pins.
-  * @param pin One of pins BTN_LIGHT, BTN_MODE or BTN_ALARM.
+///@brief An enum defining the types of interrupt trigger you wish to scan for.
+typedef enum watch_interrupt_trigger {
+    INTERRUPT_TRIGGER_NONE = 0,
+    INTERRUPT_TRIGGER_RISING,
+    INTERRUPT_TRIGGER_FALLING,
+    INTERRUPT_TRIGGER_BOTH,
+} watch_interrupt_trigger;
+
+/// @brief Enables the external interrupt controller.
+void watch_enable_external_interrupts();
+
+/// @brief Disables the external interrupt controller.
+void watch_disable_external_interrupts();
+
+/** @brief Configures an external interrupt callback on one of the external interrupt pins.
+  * @details You can set one interrupt callback per pin, and you can monitor for a rising condition,
+  *          a falling condition, or both. If you just want to detect a button press, register your
+  *          interrupt with INTERRUPT_TRIGGER_RISING; if you want to detect an active-low interrupt
+  *          signal from a device on the nine-pin connector, use INTERRUPT_TRIGGER_FALLING. If you
+  *          want to detect both rising and falling conditions (i.e. button down and button up), use
+  *          INTERRUPT_TRIGGER_BOTH and use watch_get_pin_level to check the pin level in your callback
+  *          to determine which condition caused the interrupt.
+  * @param pin One of pins BTN_LIGHT, BTN_MODE, BTN_ALARM, or A0-A5. If the pin parameter matches one of
+  *            the three button pins, this function will also enable an internal pull-down resistor. If
+  *            the pin parameter is A0-A5, you are responsible for setting any required pull configuration
+  *            using watch_enable_pull_up or watch_enable_pull_down.
   * @param callback The function you wish to have called when the button is pressed.
-  * @note The BTN_ALARM button runs off of an interrupt in the the RTC controller, not the EIC. This
-  *       implementation detail should not make any difference to your app,
+  * @param trigger The condition on which you wish to trigger: rising, falling or both.
+  * @note The alarm button and pin A2 share an external interrupt channel EXTINT[2]; you can only use one
+  *       or the other. However! These pins both have an alternate method of triggering via the RTC tamper
+  *       interrupt, which for A2 at least has the added benefit of being able to trigger in the low-power
+  *       BACKUP mode.
+  * @see watch_register_extwake_callback
   */
+void watch_register_interrupt_callback(const uint8_t pin, ext_irq_cb_t callback, watch_interrupt_trigger trigger);
+
+__attribute__((deprecated("Use watch_register_interrupt_callback instead")))
 void watch_register_button_callback(const uint8_t pin, ext_irq_cb_t callback);
+
+__attribute__((deprecated("Use watch_enable_external_interrupts instead")))
+void watch_enable_buttons();
 /// @}
diff --git a/watch-library/watch/watch_private.c b/watch-library/watch/watch_private.c
index bfe171f1..cd9c2baa 100644
--- a/watch-library/watch/watch_private.c
+++ b/watch-library/watch/watch_private.c
@@ -40,5 +40,5 @@ void _watch_init() {
     // set up state
     btn_alarm_callback = NULL;
     a2_callback = NULL;
-    d1_callback = NULL;
+    a4_callback = NULL;
 }