Merge pull request #7154 from dhalbert/alarm-lifetime

Save wake alarm info in static storage, simplifying recording of alarm

main.c

@@ -132,7 +132,7 @@ static void reset_devices(void) {
     #endif
 }
 
-STATIC void start_mp(supervisor_allocation *heap, bool first_run) {
+STATIC void start_mp(supervisor_allocation *heap) {
     supervisor_workflow_reset();
 
     // Stack limit should be less than real stack size, so we have a chance
@@ -176,14 +176,6 @@ STATIC void start_mp(supervisor_allocation *heap, bool first_run) {
     mp_obj_list_append(mp_sys_path, MP_OBJ_NEW_QSTR(MP_QSTR__slash_lib));
 
     mp_obj_list_init((mp_obj_list_t *)mp_sys_argv, 0);
-
-    #if CIRCUITPY_ALARM
-    // Record which alarm woke us up, if any. An object may be created so the heap must be functional.
-    // There is no alarm if this is not the first time code.py or the REPL has been run.
-    shared_alarm_save_wake_alarm(first_run ? common_hal_alarm_create_wake_alarm() : mp_const_none);
-    // Reset alarm module only after we retrieved the wakeup alarm.
-    alarm_reset();
-    #endif
 }
 
 STATIC void stop_mp(void) {
@@ -373,7 +365,7 @@ STATIC void print_code_py_status_message(safe_mode_t safe_mode) {
     }
 }
 
-STATIC bool run_code_py(safe_mode_t safe_mode, bool first_run, bool *simulate_reset) {
+STATIC bool run_code_py(safe_mode_t safe_mode, bool *simulate_reset) {
     bool serial_connected_at_start = serial_connected();
     bool printed_safe_mode_message = false;
     #if CIRCUITPY_AUTORELOAD_DELAY_MS > 0
@@ -409,8 +401,8 @@ STATIC bool run_code_py(safe_mode_t safe_mode, bool first_run, bool *simulate_re
 
         supervisor_allocation *heap = allocate_remaining_memory();
 
-        // Prepare the VM state. Includes an alarm check/reset for sleep.
+        // Prepare the VM state.
-        start_mp(heap, first_run);
+        start_mp(heap);
 
         #if CIRCUITPY_USB
         usb_setup_with_vm();
@@ -755,8 +747,7 @@ STATIC void __attribute__ ((noinline)) run_boot_py(safe_mode_t safe_mode) {
 
     supervisor_allocation *heap = allocate_remaining_memory();
 
-    // true means this is the first set of VM's after a hard reset.
+    start_mp(heap);
-    start_mp(heap, true);
 
     #if CIRCUITPY_USB
     // Set up default USB values after boot.py VM starts but before running boot.py.
@@ -853,12 +844,12 @@ STATIC void __attribute__ ((noinline)) run_boot_py(safe_mode_t safe_mode) {
     #endif
 }
 
-STATIC int run_repl(bool first_run) {
+STATIC int run_repl(void) {
     int exit_code = PYEXEC_FORCED_EXIT;
     stack_resize();
     filesystem_flush();
     supervisor_allocation *heap = allocate_remaining_memory();
-    start_mp(heap, first_run);
+    start_mp(heap);
 
     #if CIRCUITPY_USB
     usb_setup_with_vm();
@@ -968,6 +959,15 @@ int __attribute__((used)) main(void) {
         safe_mode = NO_CIRCUITPY;
     }
 
+    #if CIRCUITPY_ALARM
+    // Record which alarm woke us up, if any.
+    // common_hal_alarm_record_wake_alarm() should return a static, non-heap object
+    shared_alarm_save_wake_alarm(common_hal_alarm_record_wake_alarm());
+    // Then reset the alarm system. It's not reset in reset_port(), because that's also called
+    // on VM teardown, which would clear any alarm setup.
+    alarm_reset();
+    #endif
+
     // Reset everything and prep MicroPython to run boot.py.
     reset_port();
     // Port-independent devices, like CIRCUITPY_BLEIO_HCI.
@@ -1001,20 +1001,21 @@ int __attribute__((used)) main(void) {
     // Boot script is finished, so now go into REPL or run code.py.
     int exit_code = PYEXEC_FORCED_EXIT;
     bool skip_repl = true;
-    bool first_run = true;
+    bool simulate_reset = true;
-    bool simulate_reset;
     for (;;) {
-        simulate_reset = false;
         if (!skip_repl) {
-            exit_code = run_repl(first_run);
+            exit_code = run_repl();
             supervisor_set_run_reason(RUN_REASON_REPL_RELOAD);
         }
         if (exit_code == PYEXEC_FORCED_EXIT) {
-            if (!first_run) {
+            if (!simulate_reset) {
                 serial_write_compressed(translate("soft reboot\n"));
             }
             if (pyexec_mode_kind == PYEXEC_MODE_FRIENDLY_REPL) {
-                skip_repl = run_code_py(safe_mode, first_run, &simulate_reset);
+                // If code.py did a fake deep sleep, pretend that we
+                // are running code.py for the first time after a hard
+                // reset. This will preserve any alarm information.
+                skip_repl = run_code_py(safe_mode, &simulate_reset);
             } else {
                 skip_repl = false;
             }
@@ -1022,10 +1023,10 @@ int __attribute__((used)) main(void) {
             break;
         }
 
-        // Either the REPL or code.py has run and finished.
+        #if CIRCUITPY_ALARM
-        // If code.py did a fake deep sleep, pretend that we are running code.py for
+        shared_alarm_save_wake_alarm(simulate_reset ? common_hal_alarm_record_wake_alarm() : mp_const_none);
-        // the first time after a hard reset. This will preserve any alarm information.
+        alarm_reset();
-        first_run = simulate_reset;
+        #endif
     }
     mp_deinit();
     return 0;

ports/atmel-samd/common-hal/alarm/SleepMemory.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_SLEEPMEMORY_H
+#pragma once
-#define MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_SLEEPMEMORY_H
 
 #include "py/obj.h"
 
@@ -34,5 +33,3 @@ typedef struct {
 } alarm_sleep_memory_obj_t;
 
 extern void alarm_sleep_memory_reset(void);
-
-#endif // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_SLEEPMEMORY_H

ports/atmel-samd/common-hal/alarm/__init__.c

@@ -48,6 +48,10 @@ const alarm_sleep_memory_obj_t alarm_sleep_memory_obj = {
     },
 };
 
+// Non-heap alarm object recording alarm (if any) that woke up CircuitPython after light or deep sleep.
+// This object lives across VM instantiations, so none of these objects can contain references to the heap.
+alarm_wake_alarm_union_t alarm_wake_alarm;
+
 void alarm_reset(void) {
     // Reset the alarm flag
     alarm_pin_pinalarm_reset();
@@ -57,7 +61,7 @@ void alarm_reset(void) {
 void alarm_get_wakeup_cause(void) {
     // Called from rtc_init, just before SWRST of RTC.  It is called
     // at an early stage of main(), to save TAMPID from SWRST.  Later,
-    // common_hal_alarm_create_wake_alarm is called to make a wakeup
+    // common_hal_alarm_record_wake_alarm is called to make a wakeup
     // alarm from the deep sleep.
 
     TAMPID = RTC->MODE0.TAMPID.reg;
@@ -67,7 +71,7 @@ bool common_hal_alarm_woken_from_sleep(void) {
     return alarm_pin_pinalarm_woke_this_cycle() || alarm_time_timealarm_woke_this_cycle();
 }
 
-mp_obj_t common_hal_alarm_create_wake_alarm(void) {
+mp_obj_t common_hal_alarm_record_wake_alarm(void) {
     // Called from main.c on the first start up, just before alarm_reset.
     // Return a copy of wakeup alarm from deep sleep / fake deep sleep.
     // In case of fake sleep, status should be left in TimeAlarm/PinAlarm.
@@ -76,13 +80,13 @@ mp_obj_t common_hal_alarm_create_wake_alarm(void) {
     if (alarm_pin_pinalarm_woke_this_cycle()) {
         TAMPID = RTC->MODE0.TAMPID.reg;
         RTC->MODE0.TAMPID.reg = TAMPID;         // clear register
-        return alarm_pin_pinalarm_create_wakeup_alarm(TAMPID);
+        return alarm_pin_pinalarm_record_wake_alarm(TAMPID);
     }
     if (alarm_time_timealarm_woke_this_cycle() || (true_deep && TAMPID == 0)) {
-        return alarm_time_timealarm_create_wakeup_alarm();
+        return alarm_time_timealarm_record_wake_alarm();
     }
     if (true_deep) {
-        return alarm_pin_pinalarm_create_wakeup_alarm(TAMPID);
+        return alarm_pin_pinalarm_record_wake_alarm(TAMPID);
     }
     return mp_const_none;
 }

ports/atmel-samd/common-hal/alarm/__init__.h

@@ -24,10 +24,11 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM__INIT__H
+#pragma once
-#define MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM__INIT__H
 
 #include "common-hal/alarm/SleepMemory.h"
+#include "common-hal/alarm/pin/PinAlarm.h"
+#include "common-hal/alarm/time/TimeAlarm.h"
 
 extern const alarm_sleep_memory_obj_t alarm_sleep_memory_obj;
 
@@ -53,8 +54,13 @@ typedef enum {
     SAMD_WAKEUP_RTC
 } samd_sleep_source_t;
 
-extern void alarm_set_wakeup_reason(samd_sleep_source_t reason);
+typedef union {
-void alarm_get_wakeup_cause(void);
+    alarm_pin_pinalarm_obj_t pin_alarm;
-extern void alarm_reset(void);
+    alarm_time_timealarm_obj_t time_alarm;
+} alarm_wake_alarm_union_t;
 
-#endif // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM__INIT__H
+extern alarm_wake_alarm_union_t alarm_wake_alarm;
+
+extern void alarm_set_wakeup_reason(samd_sleep_source_t reason);
+extern void alarm_get_wakeup_cause(void);
+extern void alarm_reset(void);

ports/atmel-samd/common-hal/alarm/pin/PinAlarm.c

@@ -31,9 +31,9 @@
 #include "hal/include/hal_gpio.h"
 // #include <stdio.h>
 
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/pin/PinAlarm.h"
 #include "shared-bindings/microcontroller/__init__.h"
-#include "shared-bindings/microcontroller/Pin.h"
 #include "common-hal/alarm/__init__.h"
 
 // This variable stores whether a PinAlarm woke in light sleep or fake deep sleep
@@ -128,12 +128,11 @@ mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t
     return mp_const_none;
 }
 
-mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(uint32_t TAMPID) {
+mp_obj_t alarm_pin_pinalarm_record_wake_alarm(uint32_t TAMPID) {
-    // Create tamper alarm that caused wakeup from deep sleep
+    alarm_pin_pinalarm_obj_t *const alarm = &alarm_wake_alarm.pin_alarm;
 
     for (samd_tamper_pin_t *t = TAMPER_PINS; t->n >= 0; t++) {
         if (TAMPID & (1 << t->n)) {
-            alarm_pin_pinalarm_obj_t *alarm = m_new_obj(alarm_pin_pinalarm_obj_t);
             alarm->base.type = &alarm_pin_pinalarm_type;
             alarm->pin = t->pin;
             return alarm;

ports/atmel-samd/common-hal/alarm/pin/PinAlarm.h

@@ -24,12 +24,13 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_PINALARM_H
+#pragma once
-#define MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_PINALARM_H
 
 #include "py/obj.h"
 #include "py/objtuple.h"
 
+#include "shared-bindings/microcontroller/Pin.h"
+
 typedef struct {
     mp_obj_base_t base;
     const mcu_pin_obj_t *pin;
@@ -39,7 +40,7 @@ typedef struct {
 } alarm_pin_pinalarm_obj_t;
 
 mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(uint32_t TAMPID);
+mp_obj_t alarm_pin_pinalarm_record_wake_alarm(uint32_t TAMPID);
 
 void pin_alarm_callback(uint8_t num);
 void alarm_pin_pinalarm_reset(void);
@@ -47,5 +48,3 @@ void alarm_pin_pinalarm_deinit_alarms(size_t n_alarms, const mp_obj_t *alarms);
 void alarm_pin_pinalarm_set_alarms(bool deep_sleep, size_t n_alarms, const mp_obj_t *alarms);
 void alarm_pin_pinalarm_prepare_for_deep_sleep(void);
 bool alarm_pin_pinalarm_woke_this_cycle(void);
-
-#endif  // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_PINALARM_H

ports/atmel-samd/common-hal/alarm/time/TimeAlarm.c

@@ -27,9 +27,9 @@
 #include "py/runtime.h"
 #include "hpl/pm/hpl_pm_base.h"
 
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/time/TimeAlarm.h"
 #include "shared-bindings/time/__init__.h"
-#include "common-hal/alarm/__init__.h"
 #include "supervisor/port.h"
 
 STATIC volatile bool woke_up = false;
@@ -58,13 +58,14 @@ mp_obj_t alarm_time_timealarm_find_triggered_alarm(size_t n_alarms, const mp_obj
     return mp_const_none;
 }
 
-mp_obj_t alarm_time_timealarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_time_timealarm_record_wake_alarm(void) {
-    alarm_time_timealarm_obj_t *timer = m_new_obj(alarm_time_timealarm_obj_t);
+    alarm_time_timealarm_obj_t *const alarm = &alarm_wake_alarm.time_alarm;
-    timer->base.type = &alarm_time_timealarm_type;
+
+    alarm->base.type = &alarm_time_timealarm_type;
     // TODO: Set monotonic_time based on the RTC state.
     //       Or don't, most of the other ports don't have this either.
-    timer->monotonic_time = 0.0f;
+    alarm->monotonic_time = 0.0f;
-    return timer;
+    return alarm;
 }
 
 void time_alarm_callback(void) {

ports/atmel-samd/common-hal/alarm/time/TimeAlarm.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_TIMEALARM_H
+#pragma once
-#define MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_TIMEALARM_H
 
 #include "py/obj.h"
 
@@ -35,12 +34,10 @@ typedef struct {
 } alarm_time_timealarm_obj_t;
 
 mp_obj_t alarm_time_timealarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_time_timealarm_create_wakeup_alarm(void);
+mp_obj_t alarm_time_timealarm_record_wake_alarm(void);
 void time_alarm_callback(void);
 bool alarm_time_timealarm_woke_this_cycle(void);
 void alarm_time_timealarm_set_alarms(bool deep_sleep, size_t n_alarms, const mp_obj_t *alarms);
 void alarm_time_timealarm_reset(void);
 
 void alarm_time_timealarm_prepare_for_deep_sleep(void);
-
-#endif  // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_TIMEALARM_H

ports/atmel-samd/common-hal/alarm/touch/TouchAlarm.h

@@ -24,12 +24,9 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_TOUCHALARM_H
+#pragma once
-#define MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_TOUCHALARM_H
 
 typedef struct {
     mp_obj_base_t base;
     const mcu_pin_obj_t *pin;
 } alarm_touch_touchalarm_obj_t;
-
-#endif  // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_ALARM_TOUCHALARM_H

ports/espressif/common-hal/alarm/SleepMemory.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_ESPRESSIF_COMMON_HAL_ALARM_SLEEPMEMORY_H
+#pragma once
-#define MICROPY_INCLUDED_ESPRESSIF_COMMON_HAL_ALARM_SLEEPMEMORY_H
 
 #include "py/obj.h"
 
@@ -49,5 +48,3 @@ typedef struct {
 } alarm_sleep_memory_obj_t;
 
 extern void alarm_sleep_memory_reset(void);
-
-#endif // MICROPY_INCLUDED_ESPRESSIF_COMMON_HAL_ALARM_SLEEPMEMORY_H

ports/espressif/common-hal/alarm/__init__.c

@@ -58,6 +58,10 @@ const alarm_sleep_memory_obj_t alarm_sleep_memory_obj = {
     },
 };
 
+// Non-heap alarm object recording alarm (if any) that woke up CircuitPython after light or deep sleep.
+// This object lives across VM instantiations, so none of these objects can contain references to the heap.
+alarm_wake_alarm_union_t alarm_wake_alarm;
+
 void alarm_reset(void) {
     alarm_sleep_memory_reset();
     alarm_pin_pinalarm_reset();
@@ -90,27 +94,27 @@ bool common_hal_alarm_woken_from_sleep(void) {
     return _get_wakeup_cause() != ESP_SLEEP_WAKEUP_UNDEFINED;
 }
 
-mp_obj_t common_hal_alarm_create_wake_alarm(void) {
+mp_obj_t common_hal_alarm_record_wake_alarm(void) {
     // If woken from deep sleep, create a copy alarm similar to what would have
     // been passed in originally. Otherwise, just return none
     esp_sleep_wakeup_cause_t cause = _get_wakeup_cause();
     switch (cause) {
         case ESP_SLEEP_WAKEUP_TIMER: {
-            return alarm_time_timealarm_create_wakeup_alarm();
+            return alarm_time_timealarm_record_wake_alarm();
         }
 
         case ESP_SLEEP_WAKEUP_GPIO:
         case ESP_SLEEP_WAKEUP_EXT0:
         case ESP_SLEEP_WAKEUP_EXT1: {
-            return alarm_pin_pinalarm_create_wakeup_alarm();
+            return alarm_pin_pinalarm_record_wake_alarm();
         }
 
         case ESP_SLEEP_WAKEUP_TOUCHPAD: {
-            return alarm_touch_touchalarm_create_wakeup_alarm();
+            return alarm_touch_touchalarm_record_wake_alarm();
         }
 
         case ESP_SLEEP_WAKEUP_ULP: {
-            return alarm_coproc_coprocalarm_create_wakeup_alarm();
+            return alarm_coproc_coprocalarm_record_wake_alarm();
         }
 
         case ESP_SLEEP_WAKEUP_UNDEFINED:

ports/espressif/common-hal/alarm/__init__.h

@@ -24,13 +24,22 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_ESPRESSIF_COMMON_HAL_ALARM__INIT__H
+#pragma once
-#define MICROPY_INCLUDED_ESPRESSIF_COMMON_HAL_ALARM__INIT__H
 
 #include "common-hal/alarm/SleepMemory.h"
+#include "common-hal/alarm/coproc/CoprocAlarm.h"
+#include "common-hal/alarm/pin/PinAlarm.h"
+#include "common-hal/alarm/time/TimeAlarm.h"
+#include "common-hal/alarm/touch/TouchAlarm.h"
 
-const alarm_sleep_memory_obj_t alarm_sleep_memory_obj;
+typedef union {
+    alarm_coproc_coprocalarm_obj_t coproc_alarm;
+    alarm_pin_pinalarm_obj_t pin_alarm;
+    alarm_time_timealarm_obj_t time_alarm;
+    alarm_touch_touchalarm_obj_t touch_alarm;
+} alarm_wake_alarm_union_t;
+
+extern alarm_wake_alarm_union_t alarm_wake_alarm;
+extern const alarm_sleep_memory_obj_t alarm_sleep_memory_obj;
 
 extern void alarm_reset(void);
-
-#endif // MICROPY_INCLUDED_ESPRESSIF_COMMON_HAL_ALARM__INIT__H

ports/espressif/common-hal/alarm/coproc/CoprocAlarm.c

@@ -24,6 +24,7 @@
  * THE SOFTWARE.
  */
 
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/coproc/CoprocAlarm.h"
 #include "shared-bindings/coproc/__init__.h"
 
@@ -47,9 +48,9 @@ mp_obj_t alarm_coproc_coprocalarm_find_triggered_alarm(const size_t n_alarms, co
     return mp_const_none;
 }
 
-mp_obj_t alarm_coproc_coprocalarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_coproc_coprocalarm_record_wake_alarm(void) {
-    // Create CoprocAlarm object.
+    alarm_coproc_coprocalarm_obj_t *const alarm = &alarm_wake_alarm.coproc_alarm;
-    alarm_coproc_coprocalarm_obj_t *alarm = m_new_obj(alarm_coproc_coprocalarm_obj_t);
+
     alarm->base.type = &alarm_coproc_coprocalarm_type;
     return alarm;
 }
@@ -111,7 +112,7 @@ mp_obj_t alarm_coproc_coprocalarm_find_triggered_alarm(const size_t n_alarms, co
     return mp_const_none;
 }
 
-mp_obj_t alarm_coproc_coprocalarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_coproc_coprocalarm_record_wake_alarm(void) {
     return mp_const_none;
 }
 

ports/espressif/common-hal/alarm/coproc/CoprocAlarm.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_COMMON_HAL_ALARM_COPROC_COPROCALARM_H
+#pragma once
-#define MICROPY_INCLUDED_COMMON_HAL_ALARM_COPROC_COPROCALARM_H
 
 #include "py/obj.h"
 #include "py/runtime.h"
@@ -38,11 +37,9 @@ typedef struct {
 } alarm_coproc_coprocalarm_obj_t;
 
 mp_obj_t alarm_coproc_coprocalarm_find_triggered_alarm(const size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_coproc_coprocalarm_create_wakeup_alarm(void);
+mp_obj_t alarm_coproc_coprocalarm_record_wake_alarm(void);
 
 void alarm_coproc_coprocalarm_prepare_for_deep_sleep(void);
 void alarm_coproc_coprocalarm_reset(void);
 void alarm_coproc_coprocalarm_set_alarm(const bool deep_sleep, const size_t n_alarms, const mp_obj_t *alarms);
 bool alarm_coproc_coprocalarm_woke_this_cycle(void);
-
-#endif  // MICROPY_INCLUDED_COMMON_HAL_ALARM_COPROC_COPROCALARM_H

ports/espressif/common-hal/alarm/pin/PinAlarm.c

@@ -26,10 +26,10 @@
  */
 
 #include "py/runtime.h"
-
 #include "supervisor/port.h"
+
+#include "common-hal/alarm/__init__.h"
 #include "shared-bindings/alarm/pin/PinAlarm.h"
-#include "shared-bindings/microcontroller/Pin.h"
 #include "shared-bindings/microcontroller/__init__.h"
 
 #include "esp_sleep.h"
@@ -111,7 +111,7 @@ mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t
     return mp_const_none;
 }
 
-mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_pin_pinalarm_record_wake_alarm(void) {
     esp_sleep_wakeup_cause_t cause = esp_sleep_get_wakeup_cause();
 
     // Pin status will persist into a fake deep sleep
@@ -135,7 +135,8 @@ mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(void) {
         }
     }
 
-    alarm_pin_pinalarm_obj_t *alarm = m_new_obj(alarm_pin_pinalarm_obj_t);
+    alarm_pin_pinalarm_obj_t *const alarm = &alarm_wake_alarm.pin_alarm;
+
     alarm->base.type = &alarm_pin_pinalarm_type;
     alarm->pin = NULL;
     // Map the pin number back to a pin object.

ports/espressif/common-hal/alarm/pin/PinAlarm.h

@@ -24,9 +24,13 @@
  * THE SOFTWARE.
  */
 
+#pragma once
+
 #include "py/obj.h"
 #include "py/objtuple.h"
 
+#include "shared-bindings/microcontroller/Pin.h"
+
 typedef struct {
     mp_obj_base_t base;
     const mcu_pin_obj_t *pin;
@@ -35,7 +39,7 @@ typedef struct {
 } alarm_pin_pinalarm_obj_t;
 
 mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(void);
+mp_obj_t alarm_pin_pinalarm_record_wake_alarm(void);
 
 void alarm_pin_pinalarm_prepare_for_deep_sleep(void);
 void alarm_pin_pinalarm_reset(void);

ports/espressif/common-hal/alarm/time/TimeAlarm.c

@@ -31,6 +31,7 @@
 
 #include "components/esp_timer/include/esp_timer.h"
 
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/time/TimeAlarm.h"
 #include "shared-bindings/time/__init__.h"
 
@@ -51,12 +52,13 @@ mp_obj_t alarm_time_timealarm_find_triggered_alarm(size_t n_alarms, const mp_obj
     return mp_const_none;
 }
 
-mp_obj_t alarm_time_timealarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_time_timealarm_record_wake_alarm(void) {
-    alarm_time_timealarm_obj_t *timer = m_new_obj(alarm_time_timealarm_obj_t);
+    alarm_time_timealarm_obj_t *const alarm = &alarm_wake_alarm.time_alarm;
-    timer->base.type = &alarm_time_timealarm_type;
+
+    alarm->base.type = &alarm_time_timealarm_type;
     // TODO: Set monotonic_time based on the RTC state.
-    timer->monotonic_time = 0.0f;
+    alarm->monotonic_time = 0.0f;
-    return timer;
+    return alarm;
 }
 
 esp_timer_handle_t pretend_sleep_timer;

ports/espressif/common-hal/alarm/time/TimeAlarm.h

@@ -24,6 +24,7 @@
  * THE SOFTWARE.
  */
 
+#pragma once
 
 #include "py/obj.h"
 
@@ -33,7 +34,7 @@ typedef struct {
 } alarm_time_timealarm_obj_t;
 
 mp_obj_t alarm_time_timealarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_time_timealarm_create_wakeup_alarm(void);
+mp_obj_t alarm_time_timealarm_record_wake_alarm(void);
 
 void alarm_time_timealarm_reset(void);
 void alarm_time_timealarm_set_alarms(bool deep_sleep, size_t n_alarms, const mp_obj_t *alarms);

ports/espressif/common-hal/alarm/touch/TouchAlarm.c

@@ -24,6 +24,7 @@
  * THE SOFTWARE.
  */
 
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/touch/TouchAlarm.h"
 #include "shared-bindings/microcontroller/__init__.h"
 #include "shared-bindings/microcontroller/Pin.h"
@@ -52,9 +53,9 @@ mp_obj_t alarm_touch_touchalarm_find_triggered_alarm(const size_t n_alarms, cons
     return mp_const_none;
 }
 
-mp_obj_t alarm_touch_touchalarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_touch_touchalarm_record_wake_alarm(void) {
-    // Create TouchAlarm object.
+    alarm_touch_touchalarm_obj_t *const alarm = &alarm_wake_alarm.touch_alarm;
-    alarm_touch_touchalarm_obj_t *alarm = m_new_obj(alarm_touch_touchalarm_obj_t);
+
     alarm->base.type = &alarm_touch_touchalarm_type;
     alarm->pin = NULL;
 

ports/espressif/common-hal/alarm/touch/TouchAlarm.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_COMMON_HAL_ALARM_TOUCH_TOUCHALARM_H
+#pragma once
-#define MICROPY_INCLUDED_COMMON_HAL_ALARM_TOUCH_TOUCHALARM_H
 
 #include "py/obj.h"
 #include "common-hal/microcontroller/Pin.h"
@@ -36,11 +35,9 @@ typedef struct {
 } alarm_touch_touchalarm_obj_t;
 
 mp_obj_t alarm_touch_touchalarm_find_triggered_alarm(const size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_touch_touchalarm_create_wakeup_alarm(void);
+mp_obj_t alarm_touch_touchalarm_record_wake_alarm(void);
 
 void alarm_touch_touchalarm_prepare_for_deep_sleep(void);
 void alarm_touch_touchalarm_reset(void);
 void alarm_touch_touchalarm_set_alarm(const bool deep_sleep, const size_t n_alarms, const mp_obj_t *alarms);
 bool alarm_touch_touchalarm_woke_this_cycle(void);
-
-#endif  // MICROPY_INCLUDED_COMMON_HAL_ALARM_TOUCH_TOUCHALARM_H

ports/nrf/common-hal/alarm/SleepMemory.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_NRF_COMMON_HAL_ALARM_SLEEPMEMORY_H
+#pragma once
-#define MICROPY_INCLUDED_NRF_COMMON_HAL_ALARM_SLEEPMEMORY_H
 
 #include "py/obj.h"
 
@@ -37,5 +36,3 @@ typedef struct {
 
 extern void set_memory_retention(void);
 extern void alarm_sleep_memory_reset(void);
-
-#endif // MICROPY_INCLUDED_NRF_COMMON_HAL_ALARM_SLEEPMEMORY_H

ports/nrf/common-hal/alarm/__init__.c

@@ -56,6 +56,10 @@ const alarm_sleep_memory_obj_t alarm_sleep_memory_obj = {
     },
 };
 
+// Non-heap alarm object recording alarm (if any) that woke up CircuitPython after light or deep sleep.
+// This object lives across VM instantiations, so none of these objects can contain references to the heap.
+alarm_wake_alarm_union_t alarm_wake_alarm;
+
 void alarm_reset(void) {
     alarm_sleep_memory_reset();
     alarm_pin_pinalarm_reset();
@@ -115,19 +119,19 @@ bool common_hal_alarm_woken_from_sleep(void) {
            || cause == NRF_SLEEP_WAKEUP_TOUCHPAD;
 }
 
-mp_obj_t common_hal_alarm_create_wake_alarm(void) {
+mp_obj_t common_hal_alarm_record_wake_alarm(void) {
     // If woken from deep sleep, create a copy alarm similar to what would have
     // been passed in originally. Otherwise, just return none
     nrf_sleep_source_t cause = _get_wakeup_cause();
     switch (cause) {
         case NRF_SLEEP_WAKEUP_TIMER: {
-            return alarm_time_timealarm_create_wakeup_alarm();
+            return alarm_time_timealarm_record_wake_alarm();
         }
         case NRF_SLEEP_WAKEUP_TOUCHPAD: {
-            return alarm_touch_touchalarm_create_wakeup_alarm();
+            return alarm_touch_touchalarm_record_wake_alarm();
         }
         case NRF_SLEEP_WAKEUP_GPIO: {
-            return alarm_pin_pinalarm_create_wakeup_alarm();
+            return alarm_pin_pinalarm_record_wake_alarm();
         }
         default:
             break;

ports/nrf/common-hal/alarm/__init__.h

@@ -25,10 +25,12 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_NRF_COMMON_HAL_ALARM__INIT__H
+#pragma once
-#define MICROPY_INCLUDED_NRF_COMMON_HAL_ALARM__INIT__H
 
 #include "common-hal/alarm/SleepMemory.h"
+#include "common-hal/alarm/pin/PinAlarm.h"
+#include "common-hal/alarm/time/TimeAlarm.h"
+#include "common-hal/alarm/touch/TouchAlarm.h"
 
 typedef enum {
     NRF_SLEEP_WAKEUP_UNDEFINED,
@@ -40,6 +42,13 @@ typedef enum {
     NRF_SLEEP_WAKEUP_ZZZ
 } nrf_sleep_source_t;
 
+typedef union {
+    alarm_pin_pinalarm_obj_t pin_alarm;
+    alarm_time_timealarm_obj_t time_alarm;
+    alarm_touch_touchalarm_obj_t touch_alarm;
+} alarm_wake_alarm_union_t;
+
+extern alarm_wake_alarm_union_t alarm_wake_alarm;
 extern const alarm_sleep_memory_obj_t alarm_sleep_memory_obj;
 
 enum {
@@ -52,5 +61,3 @@ extern uint8_t sleepmem_wakeup_event;
 extern uint8_t sleepmem_wakeup_pin;
 
 extern void alarm_reset(void);
-
-#endif // MICROPY_INCLUDED_NRF_COMMON_HAL_ALARM__INIT__H

ports/nrf/common-hal/alarm/pin/PinAlarm.c

@@ -30,10 +30,9 @@
 #include <stdio.h>
 #include <assert.h>
 
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/pin/PinAlarm.h"
 #include "shared-bindings/microcontroller/__init__.h"
-#include "shared-bindings/microcontroller/Pin.h"
-#include "common-hal/alarm/__init__.h"
 
 #include "nrfx.h"
 #include "nrf_gpio.h"
@@ -101,8 +100,9 @@ mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t
     return mp_const_none;
 }
 
-mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_pin_pinalarm_record_wake_alarm(void) {
-    alarm_pin_pinalarm_obj_t *alarm = m_new_obj(alarm_pin_pinalarm_obj_t);
+    alarm_pin_pinalarm_obj_t *const alarm = &alarm_wake_alarm.pin_alarm;
+
     alarm->base.type = &alarm_pin_pinalarm_type;
     alarm->pin = NULL;
     // Map the pin number back to a pin object.

ports/nrf/common-hal/alarm/pin/PinAlarm.h

@@ -24,9 +24,13 @@
  * THE SOFTWARE.
  */
 
+#pragma once
+
 #include "py/obj.h"
 #include "py/objtuple.h"
 
+#include "shared-bindings/microcontroller/Pin.h"
+
 typedef struct {
     mp_obj_base_t base;
     const mcu_pin_obj_t *pin;
@@ -35,7 +39,7 @@ typedef struct {
 } alarm_pin_pinalarm_obj_t;
 
 mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(void);
+mp_obj_t alarm_pin_pinalarm_record_wake_alarm(void);
 
 void alarm_pin_pinalarm_reset(void);
 void alarm_pin_pinalarm_set_alarms(bool deep_sleep, size_t n_alarms, const mp_obj_t *alarms);

ports/nrf/common-hal/alarm/time/TimeAlarm.c

@@ -28,7 +28,7 @@
 #include "py/runtime.h"
 #include <stdio.h>
 
-#include "common-hal/alarm/__init__.h"
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/time/TimeAlarm.h"
 #include "shared-bindings/time/__init__.h"
 
@@ -49,12 +49,13 @@ mp_obj_t alarm_time_timealarm_find_triggered_alarm(size_t n_alarms, const mp_obj
     return mp_const_none;
 }
 
-mp_obj_t alarm_time_timealarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_time_timealarm_record_wake_alarm(void) {
-    alarm_time_timealarm_obj_t *timer = m_new_obj(alarm_time_timealarm_obj_t);
+    alarm_time_timealarm_obj_t *const alarm = &alarm_wake_alarm.time_alarm;
-    timer->base.type = &alarm_time_timealarm_type;
+
+    alarm->base.type = &alarm_time_timealarm_type;
     // TODO: Set monotonic_time based on the RTC state.
-    timer->monotonic_time = 0.0f;
+    alarm->monotonic_time = 0.0f;
-    return timer;
+    return alarm;
 }
 
 bool alarm_time_timealarm_woke_this_cycle(void) {

ports/nrf/common-hal/alarm/time/TimeAlarm.h

@@ -24,6 +24,7 @@
  * THE SOFTWARE.
  */
 
+#pragma once
 
 #include "py/obj.h"
 
@@ -37,7 +38,7 @@ extern void port_disable_interrupt_after_ticks_ch(uint32_t channel);
 extern void port_interrupt_after_ticks_ch(uint32_t channel, uint32_t ticks);
 
 mp_obj_t alarm_time_timealarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_time_timealarm_create_wakeup_alarm(void);
+mp_obj_t alarm_time_timealarm_record_wake_alarm(void);
 
 bool alarm_time_timealarm_woke_this_cycle(void);
 void alarm_time_timealarm_set_alarms(bool deep_sleep, size_t n_alarms, const mp_obj_t *alarms);

ports/nrf/common-hal/alarm/touch/TouchAlarm.c

@@ -25,6 +25,7 @@
  */
 
 #include "py/runtime.h"
+
 #include "shared-bindings/alarm/touch/TouchAlarm.h"
 #include "shared-bindings/microcontroller/__init__.h"
 
@@ -39,7 +40,7 @@ mp_obj_t alarm_touch_touchalarm_find_triggered_alarm(const size_t n_alarms, cons
     return mp_const_none;
 }
 
-mp_obj_t alarm_touch_touchalarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_touch_touchalarm_record_wake_alarm(void) {
     return mp_const_none;
 }
 

ports/nrf/common-hal/alarm/touch/TouchAlarm.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_COMMON_HAL_ALARM_TOUCH_TOUCHALARM_H
+#pragma once
-#define MICROPY_INCLUDED_COMMON_HAL_ALARM_TOUCH_TOUCHALARM_H
 
 #include "py/obj.h"
 #include "common-hal/microcontroller/Pin.h"
@@ -37,11 +36,9 @@ typedef struct {
 
 // Find the alarm object that caused us to wake up or create an equivalent one.
 mp_obj_t alarm_touch_touchalarm_find_triggered_alarm(const size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_touch_touchalarm_create_wakeup_alarm(void);
+mp_obj_t alarm_touch_touchalarm_record_wake_alarm(void);
 // Check for the wake up alarm from pretend deep sleep.
 void alarm_touch_touchalarm_set_alarm(const bool deep_sleep, const size_t n_alarms, const mp_obj_t *alarms);
 void alarm_touch_touchalarm_prepare_for_deep_sleep(void);
 bool alarm_touch_touchalarm_woke_this_cycle(void);
 void alarm_touch_touchalarm_reset(void);
-
-#endif  // MICROPY_INCLUDED_COMMON_HAL_ALARM_TOUCH_TOUCHALARM_H

ports/nrf/supervisor/port.c

@@ -64,11 +64,11 @@
 
 #include "lib/tinyusb/src/device/usbd.h"
 
-#ifdef CIRCUITPY_AUDIOBUSIO
+#if CIRCUITPY_AUDIOBUSIO
 #include "common-hal/audiobusio/I2SOut.h"
 #endif
 
-#ifdef CIRCUITPY_AUDIOPWMIO
+#if CIRCUITPY_AUDIOPWMIO
 #include "common-hal/audiopwmio/PWMAudioOut.h"
 #endif
 

ports/raspberrypi/common-hal/alarm/SleepMemory.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_ALARM_SLEEPMEMORY_H
+#pragma once
-#define MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_ALARM_SLEEPMEMORY_H
 
 #include "py/obj.h"
 
@@ -34,5 +33,3 @@ typedef struct {
 } alarm_sleep_memory_obj_t;
 
 extern void alarm_sleep_memory_reset(void);
-
-#endif // MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_ALARM_SLEEPMEMORY_H

ports/raspberrypi/common-hal/alarm/__init__.c

@@ -96,6 +96,10 @@ const alarm_sleep_memory_obj_t alarm_sleep_memory_obj = {
     },
 };
 
+// Non-heap alarm object recording alarm (if any) that woke up CircuitPython after light or deep sleep.
+// This object lives across VM instantiations, so none of these objects can contain references to the heap.
+alarm_wake_alarm_union_t alarm_wake_alarm;
+
 void alarm_reset(void) {
     alarm_sleep_memory_reset();
     alarm_pin_pinalarm_reset();
@@ -131,17 +135,17 @@ bool common_hal_alarm_woken_from_sleep(void) {
     return _get_wakeup_cause() != RP_SLEEP_WAKEUP_UNDEF;
 }
 
-mp_obj_t common_hal_alarm_create_wake_alarm(void) {
+mp_obj_t common_hal_alarm_record_wake_alarm(void) {
     // If woken from deep sleep, create a copy alarm similar to what would have
     // been passed in originally. Otherwise, just return none
     uint8_t cause = _get_wakeup_cause();
     switch (cause) {
         case RP_SLEEP_WAKEUP_RTC: {
-            return alarm_time_timealarm_create_wakeup_alarm();
+            return alarm_time_timealarm_record_wake_alarm();
         }
 
         case RP_SLEEP_WAKEUP_GPIO: {
-            return alarm_pin_pinalarm_create_wakeup_alarm();
+            return alarm_pin_pinalarm_record_wake_alarm();
         }
 
         case RP_SLEEP_WAKEUP_UNDEF:

ports/raspberrypi/common-hal/alarm/__init__.h

@@ -24,10 +24,11 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_ALARM__INIT__H
+#pragma once
-#define MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_ALARM__INIT__H
 
 #include "common-hal/alarm/SleepMemory.h"
+#include "common-hal/alarm/pin/PinAlarm.h"
+#include "common-hal/alarm/time/TimeAlarm.h"
 
 #include "hardware/regs/clocks.h"
 
@@ -35,8 +36,12 @@
 #define RP_SLEEP_WAKEUP_GPIO    1
 #define RP_SLEEP_WAKEUP_RTC     2
 
+typedef union {
+    alarm_pin_pinalarm_obj_t pin_alarm;
+    alarm_time_timealarm_obj_t time_alarm;
+} alarm_wake_alarm_union_t;
+
+extern alarm_wake_alarm_union_t alarm_wake_alarm;
 extern const alarm_sleep_memory_obj_t alarm_sleep_memory_obj;
 
 extern void alarm_reset(void);
-
-#endif // MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_ALARM__INIT__H

ports/raspberrypi/common-hal/alarm/pin/PinAlarm.c

@@ -26,10 +26,10 @@
 
 #include "py/runtime.h"
 
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/pin/PinAlarm.h"
 #include "shared-bindings/microcontroller/__init__.h"
 #include "common-hal/microcontroller/__init__.h"
-#include "shared-bindings/microcontroller/Pin.h"
 
 #include "pico/stdlib.h"
 #include "hardware/gpio.h"
@@ -94,10 +94,12 @@ mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t
     return mp_const_none;
 }
 
-mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_pin_pinalarm_record_wake_alarm(void) {
-    alarm_pin_pinalarm_obj_t *alarm = m_new_obj(alarm_pin_pinalarm_obj_t);
+    alarm_pin_pinalarm_obj_t *const alarm = &alarm_wake_alarm.pin_alarm;
+
     alarm->base.type = &alarm_pin_pinalarm_type;
     // TODO: how to obtain the correct pin from memory?
+    alarm->pin = NULL;
     return alarm;
 }
 

ports/raspberrypi/common-hal/alarm/pin/PinAlarm.h

@@ -24,9 +24,13 @@
  * THE SOFTWARE.
  */
 
+#pragma once
+
 #include "py/obj.h"
 #include "py/objtuple.h"
 
+#include "shared-bindings/microcontroller/Pin.h"
+
 typedef struct {
     mp_obj_base_t base;
     const mcu_pin_obj_t *pin;
@@ -36,7 +40,7 @@ typedef struct {
 } alarm_pin_pinalarm_obj_t;
 
 mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(void);
+mp_obj_t alarm_pin_pinalarm_record_wake_alarm(void);
 
 void alarm_pin_pinalarm_reset(void);
 void alarm_pin_pinalarm_light_reset(void);

ports/raspberrypi/common-hal/alarm/time/TimeAlarm.c

@@ -26,6 +26,7 @@
 
 #include "py/runtime.h"
 
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/time/TimeAlarm.h"
 #include "shared-bindings/time/__init__.h"
 
@@ -58,12 +59,13 @@ mp_obj_t alarm_time_timealarm_find_triggered_alarm(size_t n_alarms, const mp_obj
     return mp_const_none;
 }
 
-mp_obj_t alarm_time_timealarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_time_timealarm_record_wake_alarm(void) {
-    alarm_time_timealarm_obj_t *timer = m_new_obj(alarm_time_timealarm_obj_t);
+    alarm_time_timealarm_obj_t *const alarm = &alarm_wake_alarm.time_alarm;
-    timer->base.type = &alarm_time_timealarm_type;
+
+    alarm->base.type = &alarm_time_timealarm_type;
     // TODO: Set monotonic_time based on the RTC state.
-    timer->monotonic_time = 0.0f;
+    alarm->monotonic_time = 0.0f;
-    return timer;
+    return alarm;
 }
 
 bool alarm_time_timealarm_woke_this_cycle(void) {

ports/raspberrypi/common-hal/alarm/time/TimeAlarm.h

@@ -24,6 +24,7 @@
  * THE SOFTWARE.
  */
 
+#pragma once
 
 #include "py/obj.h"
 
@@ -33,7 +34,7 @@ typedef struct {
 } alarm_time_timealarm_obj_t;
 
 mp_obj_t alarm_time_timealarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_time_timealarm_create_wakeup_alarm(void);
+mp_obj_t alarm_time_timealarm_record_wake_alarm(void);
 
 void alarm_time_timealarm_reset(void);
 void alarm_time_timealarm_set_alarms(bool deep_sleep, size_t n_alarms, const mp_obj_t *alarms);

ports/raspberrypi/common-hal/alarm/touch/TouchAlarm.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_ALARM_TOUCH_TOUCHALARM_H
+#pragma once
-#define MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_ALARM_TOUCH_TOUCHALARM_H
 
 #include "py/obj.h"
 #include "common-hal/microcontroller/Pin.h"
@@ -34,5 +33,3 @@ typedef struct {
     mp_obj_base_t base;
     const mcu_pin_obj_t *pin;
 } alarm_touch_touchalarm_obj_t;
-
-#endif  // MICROPY_INCLUDED_RASPBERRYPI_COMMON_HAL_ALARM_TOUCH_TOUCHALARM_H

ports/stm/common-hal/alarm/SleepMemory.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_SLEEPMEMORY_H
+#pragma once
-#define MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_SLEEPMEMORY_H
 
 #include "py/obj.h"
 
@@ -34,5 +33,3 @@ typedef struct {
 } alarm_sleep_memory_obj_t;
 
 extern void alarm_sleep_memory_reset(void);
-
-#endif // MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_SLEEPMEMORY_H

ports/stm/common-hal/alarm/__init__.c

@@ -47,6 +47,10 @@ const alarm_sleep_memory_obj_t alarm_sleep_memory_obj = {
     },
 };
 
+// Non-heap alarm object recording alarm (if any) that woke up CircuitPython after light or deep sleep.
+// This object lives across VM instantiations, so none of these objects can contain references to the heap.
+alarm_wake_alarm_union_t alarm_wake_alarm;
+
 STATIC stm_sleep_source_t true_deep_wake_reason;
 
 void alarm_reset(void) {
@@ -81,16 +85,16 @@ bool common_hal_alarm_woken_from_sleep(void) {
     return alarm_get_wakeup_cause() != STM_WAKEUP_UNDEF;
 }
 
-mp_obj_t common_hal_alarm_create_wake_alarm(void) {
+mp_obj_t common_hal_alarm_record_wake_alarm(void) {
     // If woken from deep sleep, create a copy alarm similar to what would have
     // been passed in originally. Otherwise, just return none
     stm_sleep_source_t cause = alarm_get_wakeup_cause();
     switch (cause) {
         case STM_WAKEUP_RTC: {
-            return alarm_time_timealarm_create_wakeup_alarm();
+            return alarm_time_timealarm_record_wake_alarm();
         }
         case STM_WAKEUP_GPIO: {
-            return alarm_pin_pinalarm_create_wakeup_alarm();
+            return alarm_pin_pinalarm_record_wake_alarm();
         }
         case STM_WAKEUP_UNDEF:
         default:

ports/stm/common-hal/alarm/__init__.h

@@ -24,10 +24,11 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM__INIT__H
+#pragma once
-#define MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM__INIT__H
 
 #include "common-hal/alarm/SleepMemory.h"
+#include "common-hal/alarm/pin/PinAlarm.h"
+#include "common-hal/alarm/time/TimeAlarm.h"
 
 extern const alarm_sleep_memory_obj_t alarm_sleep_memory_obj;
 
@@ -37,10 +38,15 @@ typedef enum {
     STM_WAKEUP_RTC
 } stm_sleep_source_t;
 
+typedef union {
+    alarm_pin_pinalarm_obj_t pin_alarm;
+    alarm_time_timealarm_obj_t time_alarm;
+} alarm_wake_alarm_union_t;
+
+extern alarm_wake_alarm_union_t alarm_wake_alarm;
+
 #define STM_ALARM_FLAG      (RTC->BKP0R)
 
 extern void alarm_set_wakeup_reason(stm_sleep_source_t reason);
-stm_sleep_source_t alarm_get_wakeup_cause(void);
+extern stm_sleep_source_t alarm_get_wakeup_cause(void);
 extern void alarm_reset(void);
-
-#endif // MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM__INIT__H

ports/stm/common-hal/alarm/pin/PinAlarm.c

@@ -26,6 +26,7 @@
 
 #include "py/runtime.h"
 
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/pin/PinAlarm.h"
 
 #include "peripherals/exti.h"
@@ -100,8 +101,9 @@ mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t
     return mp_const_none;
 }
 
-mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_pin_pinalarm_record_wake_alarm(void) {
-    alarm_pin_pinalarm_obj_t *alarm = m_new_obj(alarm_pin_pinalarm_obj_t);
+    alarm_pin_pinalarm_obj_t *const alarm = &alarm_wake_alarm.pin_alarm;
+
     alarm->base.type = &alarm_pin_pinalarm_type;
     // TODO: replace this if/when other WKUP pins are supported
     alarm->pin = &pin_PA00;

ports/stm/common-hal/alarm/pin/PinAlarm.h

@@ -24,12 +24,13 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_PINALARM_H
+#pragma once
-#define MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_PINALARM_H
 
 #include "py/obj.h"
 #include "py/objtuple.h"
 
+#include "shared-bindings/microcontroller/Pin.h"
+
 typedef struct {
     mp_obj_base_t base;
     const mcu_pin_obj_t *pin;
@@ -38,11 +39,9 @@ typedef struct {
 } alarm_pin_pinalarm_obj_t;
 
 mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(void);
+mp_obj_t alarm_pin_pinalarm_record_wake_alarm(void);
 
 void alarm_pin_pinalarm_reset(void);
 void alarm_pin_pinalarm_set_alarms(bool deep_sleep, size_t n_alarms, const mp_obj_t *alarms);
 void alarm_pin_pinalarm_prepare_for_deep_sleep(void);
 bool alarm_pin_pinalarm_woke_this_cycle(void);
-
-#endif  // MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_PINALARM_H

ports/stm/common-hal/alarm/time/TimeAlarm.c

@@ -26,6 +26,7 @@
 
 #include "py/runtime.h"
 
+#include "shared-bindings/alarm/__init__.h"
 #include "shared-bindings/alarm/time/TimeAlarm.h"
 #include "shared-bindings/time/__init__.h"
 #include "peripherals/rtc.h"
@@ -53,12 +54,13 @@ mp_obj_t alarm_time_timealarm_find_triggered_alarm(size_t n_alarms, const mp_obj
     return mp_const_none;
 }
 
-mp_obj_t alarm_time_timealarm_create_wakeup_alarm(void) {
+mp_obj_t alarm_time_timealarm_record_wake_alarm(void) {
-    alarm_time_timealarm_obj_t *timer = m_new_obj(alarm_time_timealarm_obj_t);
+    alarm_time_timealarm_obj_t *const alarm = &alarm_wake_alarm.time_alarm;
-    timer->base.type = &alarm_time_timealarm_type;
+
+    alarm->base.type = &alarm_time_timealarm_type;
     // TODO: Set monotonic_time based on the RTC state.
-    timer->monotonic_time = 0.0f;
+    alarm->monotonic_time = 0.0f;
-    return timer;
+    return alarm;
 }
 
 // This is run in the timer task. We use it to wake the main CircuitPython task.

ports/stm/common-hal/alarm/time/TimeAlarm.h

@@ -24,8 +24,7 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_TIMEALARM_H
+#pragma once
-#define MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_TIMEALARM_H
 
 #include "py/obj.h"
 
@@ -35,12 +34,10 @@ typedef struct {
 } alarm_time_timealarm_obj_t;
 
 mp_obj_t alarm_time_timealarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms);
-mp_obj_t alarm_time_timealarm_create_wakeup_alarm(void);
+mp_obj_t alarm_time_timealarm_record_wake_alarm(void);
 
 bool alarm_time_timealarm_woke_this_cycle(void);
 void alarm_time_timealarm_set_alarms(bool deep_sleep, size_t n_alarms, const mp_obj_t *alarms);
 void alarm_time_timealarm_reset(void);
 
 void alarm_time_timealarm_prepare_for_deep_sleep(void);
-
-#endif  // MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_TIMEALARM_H

ports/stm/common-hal/alarm/touch/TouchAlarm.h

@@ -24,12 +24,9 @@
  * THE SOFTWARE.
  */
 
-#ifndef MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_TOUCHALARM_H
+#pragma once
-#define MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_TOUCHALARM_H
 
 typedef struct {
     mp_obj_base_t base;
     const mcu_pin_obj_t *pin;
 } alarm_touch_touchalarm_obj_t;
-
-#endif  // MICROPY_INCLUDED_STM32_COMMON_HAL_ALARM_TOUCHALARM_H

shared-bindings/alarm/__init__.h

@@ -55,7 +55,7 @@ extern void common_hal_alarm_pretending_deep_sleep(void);
 extern mp_obj_t shared_alarm_get_wake_alarm(void);
 
 // Creates a new alarm object after exiting deep sleep (real or fake)
-extern mp_obj_t common_hal_alarm_create_wake_alarm(void);
+extern mp_obj_t common_hal_alarm_record_wake_alarm(void);
 
 // Saves alarm to global array
 void shared_alarm_save_wake_alarm(mp_obj_t alarm);