Initial work on SAMD

19 files changed, 139 insertions, 316 deletions

diff --git a/ports/atmel-samd/Makefile b/ports/atmel-samd/Makefile
index f4886f96e..5ec91a811 100644
--- a/ports/atmel-samd/Makefile
+++ b/ports/atmel-samd/Makefile
@@ -194,7 +194,6 @@ SRC_ASF := \
 	hpl/gclk/hpl_gclk.c \
 	hpl/nvmctrl/hpl_nvmctrl.c \
 	hpl/pm/hpl_pm.c \
-	hpl/rtc/hpl_rtc.c \
 	hpl/sercom/hpl_sercom.c \
 	hpl/systick/hpl_systick.c \
 	hal/utils/src/utils_list.c \
@@ -258,7 +257,6 @@ SRC_C = \
 	peripherals/samd/timers.c \
 	reset.c \
 	supervisor/shared/memory.c \
-	tick.c \
 	timer_handler.c \
 
 
diff --git a/ports/atmel-samd/background.c b/ports/atmel-samd/background.c
index ca91a31de..767c7f3b6 100644
--- a/ports/atmel-samd/background.c
+++ b/ports/atmel-samd/background.c
@@ -26,7 +26,6 @@
 #include "background.h"
 
 #include "audio_dma.h"
-#include "tick.h"
 #include "supervisor/filesystem.h"
 #include "supervisor/shared/tick.h"
 #include "supervisor/usb.h"
@@ -34,6 +33,7 @@
 #include "py/runtime.h"
 #include "shared-module/network/__init__.h"
 #include "supervisor/shared/stack.h"
+#include "supervisor/port.h"
 
 #ifdef CIRCUITPY_DISPLAYIO
 #include "shared-module/displayio/__init__.h"
@@ -92,10 +92,10 @@ void run_background_tasks(void) {
     running_background_tasks = false;
     assert_heap_ok();
 
-    last_finished_tick = supervisor_ticks_ms64();
+    last_finished_tick = port_get_raw_ticks(NULL);
     finish_background_task();
 }
 
 bool background_tasks_ok(void) {
-    return supervisor_ticks_ms64() - last_finished_tick < 1000;
+    return port_get_raw_ticks(NULL) - last_finished_tick < 1024;
 }
diff --git a/ports/atmel-samd/common-hal/audiobusio/PDMIn.c b/ports/atmel-samd/common-hal/audiobusio/PDMIn.c
index 76e66ab45..a1e35a1dc 100644
--- a/ports/atmel-samd/common-hal/audiobusio/PDMIn.c
+++ b/ports/atmel-samd/common-hal/audiobusio/PDMIn.c
@@ -49,7 +49,6 @@
 #include "samd/dma.h"
 
 #include "audio_dma.h"
-#include "tick.h"
 
 #define OVERSAMPLING 64
 #define SAMPLES_PER_BUFFER 32
diff --git a/ports/atmel-samd/common-hal/displayio/ParallelBus.c b/ports/atmel-samd/common-hal/displayio/ParallelBus.c
index 2479e3b40..405c08c64 100644
--- a/ports/atmel-samd/common-hal/displayio/ParallelBus.c
+++ b/ports/atmel-samd/common-hal/displayio/ParallelBus.c
@@ -33,8 +33,6 @@
 #include "shared-bindings/digitalio/DigitalInOut.h"
 #include "shared-bindings/microcontroller/__init__.h"
 
-#include "tick.h"
-
 void common_hal_displayio_parallelbus_construct(displayio_parallelbus_obj_t* self,
     const mcu_pin_obj_t* data0, const mcu_pin_obj_t* command, const mcu_pin_obj_t* chip_select,
     const mcu_pin_obj_t* write, const mcu_pin_obj_t* read, const mcu_pin_obj_t* reset) {
diff --git a/ports/atmel-samd/common-hal/neopixel_write/__init__.c b/ports/atmel-samd/common-hal/neopixel_write/__init__.c
index ba69174af..175527025 100644
--- a/ports/atmel-samd/common-hal/neopixel_write/__init__.c
+++ b/ports/atmel-samd/common-hal/neopixel_write/__init__.c
@@ -29,7 +29,7 @@
 
 #include "shared-bindings/neopixel_write/__init__.h"
 
-#include "tick.h"
+#include "supervisor/port.h"
 
 #ifdef SAMD51
 #include "hri/hri_cmcc_d51.h"
@@ -91,8 +91,7 @@ static void neopixel_send_buffer_core(volatile uint32_t *clraddr, uint32_t pinMa
                  "");
 }
 
-uint64_t next_start_tick_ms = 0;
-uint32_t next_start_tick_us = 1000;
+uint64_t next_start_raw_ticks = 0;
 
 void common_hal_neopixel_write(const digitalio_digitalinout_obj_t* digitalinout, uint8_t *pixels, uint32_t numBytes) {
     // This is adapted directly from the Adafruit NeoPixel library SAMD21G18A code:
@@ -101,9 +100,9 @@ void common_hal_neopixel_write(const digitalio_digitalinout_obj_t* digitalinout,
     uint32_t  pinMask;
     PortGroup* port;
 
-    // This must be called while interrupts are on in case we're waiting for a
-    // future ms tick.
-    wait_until(next_start_tick_ms, next_start_tick_us);
+    // Wait to make sure we don't append onto the last transmission. This should only be a tick or
+    // two.
+    while (port_get_raw_ticks(NULL) < next_start_raw_ticks) {}
 
     // Turn off interrupts of any kind during timing-sensitive code.
     mp_hal_disable_all_interrupts();
@@ -144,15 +143,8 @@ void common_hal_neopixel_write(const digitalio_digitalinout_obj_t* digitalinout,
 
     #endif
 
-    // ticks_ms may be out of date at this point because we stopped the
-    // interrupt. We'll risk it anyway.
-    current_tick(&next_start_tick_ms, &next_start_tick_us);
-    if (next_start_tick_us < 100) {
-        next_start_tick_ms += 1;
-        next_start_tick_us = 100 - next_start_tick_us;
-    } else {
-        next_start_tick_us -= 100;
-    }
+    // Update the next start.
+    next_start_raw_ticks = port_get_raw_ticks(NULL) + 4;
 
     // Turn on interrupts after timing-sensitive code.
     mp_hal_enable_all_interrupts();
diff --git a/ports/atmel-samd/common-hal/ps2io/Ps2.c b/ports/atmel-samd/common-hal/ps2io/Ps2.c
index 6a06864f2..2579142ad 100644
--- a/ports/atmel-samd/common-hal/ps2io/Ps2.c
+++ b/ports/atmel-samd/common-hal/ps2io/Ps2.c
@@ -41,10 +41,9 @@
 #include "samd/pins.h"
 #include "shared-bindings/microcontroller/__init__.h"
 #include "shared-bindings/ps2io/Ps2.h"
+#include "supervisor/port.h"
 #include "supervisor/shared/translate.h"
 
-#include "tick.h"
-
 #define STATE_IDLE 0
 #define STATE_RECV 1
 #define STATE_RECV_PARITY 2
@@ -168,24 +167,21 @@ static void delay_us(uint32_t t) {
 
 void ps2_interrupt_handler(uint8_t channel) {
     // Grab the current time first.
-    uint32_t current_us;
-    uint64_t current_ms;
-    current_tick(&current_ms, &current_us);
+    uint64_t current_tick = port_get_raw_ticks(NULL);
 
     ps2io_ps2_obj_t* self = get_eic_channel_data(channel);
     int data_bit = gpio_get_pin_level(self->data_pin) ? 1 : 0;
 
     // test for timeout
     if (self->state != STATE_IDLE) {
-        int64_t diff_ms = current_ms - self->last_int_ms;
-        if (diff_ms >= 2) { // a.k.a. > 1.001ms
+        int64_t diff_ms = current_tick - self->last_raw_ticks;
+        if (diff_ms > 1) { // a.k.a. > 1.001ms
             self->last_errors |= ERROR_TIMEOUT;
             self->state = STATE_IDLE;
         }
     }
 
-    self->last_int_us = current_us;
-    self->last_int_ms = current_ms;
+    self->last_raw_ticks = current_tick;
 
     if (self->state == STATE_IDLE) {
         self->bits = 0;
diff --git a/ports/atmel-samd/common-hal/ps2io/Ps2.h b/ports/atmel-samd/common-hal/ps2io/Ps2.h
index cce6ae474..588dfdd8b 100644
--- a/ports/atmel-samd/common-hal/ps2io/Ps2.h
+++ b/ports/atmel-samd/common-hal/ps2io/Ps2.h
@@ -39,8 +39,7 @@ typedef struct {
     uint8_t data_pin;
 
     uint8_t state;
-    uint64_t last_int_ms;
-    uint32_t last_int_us;
+    uint64_t last_raw_ticks;
 
     uint16_t bits;
     bool parity;
diff --git a/ports/atmel-samd/common-hal/pulseio/PulseIn.c b/ports/atmel-samd/common-hal/pulseio/PulseIn.c
index a2494f102..147081d18 100644
--- a/ports/atmel-samd/common-hal/pulseio/PulseIn.c
+++ b/ports/atmel-samd/common-hal/pulseio/PulseIn.c
@@ -42,8 +42,6 @@
 #include "shared-bindings/pulseio/PulseIn.h"
 #include "supervisor/shared/translate.h"
 
-#include "tick.h"
-
 static void pulsein_set_config(pulseio_pulsein_obj_t* self, bool first_edge) {
     uint32_t sense_setting;
     if (!first_edge) {
@@ -61,9 +59,9 @@ static void pulsein_set_config(pulseio_pulsein_obj_t* self, bool first_edge) {
 
 void pulsein_interrupt_handler(uint8_t channel) {
     // Grab the current time first.
-    uint32_t current_us;
-    uint64_t current_ms;
-    current_tick(&current_ms, &current_us);
+    uint32_t current_us = 0;
+    uint64_t current_ms = 0;
+    // current_tick(&current_ms, &current_us);
 
     // current_tick gives us the remaining us until the next tick but we want the number since the
     // last ms.
diff --git a/ports/atmel-samd/common-hal/rtc/RTC.c b/ports/atmel-samd/common-hal/rtc/RTC.c
index 4c888418b..7651fdef6 100644
--- a/ports/atmel-samd/common-hal/rtc/RTC.c
+++ b/ports/atmel-samd/common-hal/rtc/RTC.c
@@ -30,76 +30,46 @@
 #include <hal_init.h>
 #include <hpl_gclk_base.h>
 #include <hpl_pm_base.h>
-#include <hal_calendar.h>
 
 #include "py/obj.h"
 #include "py/runtime.h"
 #include "lib/timeutils/timeutils.h"
 #include "shared-bindings/rtc/__init__.h"
+#include "supervisor/port.h"
 #include "supervisor/shared/translate.h"
 
-static struct calendar_descriptor calendar;
-
-void rtc_init(void) {
-#ifdef SAMD21
-    _gclk_enable_channel(RTC_GCLK_ID, CONF_GCLK_RTC_SRC);
-#endif
-#ifdef SAMD51
-    hri_mclk_set_APBAMASK_RTC_bit(MCLK);
-#endif
-    calendar_init(&calendar, RTC);
-    calendar_set_baseyear(&calendar, 2000);
-    calendar_enable(&calendar);
-}
+// This is the time in seconds since 2000 that the RTC was started.
+static uint32_t rtc_offset = 0;
 
 void common_hal_rtc_get_time(timeutils_struct_time_t *tm) {
-    struct calendar_date_time datetime;
-    calendar_get_date_time(&calendar, &datetime);
-
-    tm->tm_year = datetime.date.year;
-    tm->tm_mon  = datetime.date.month;
-    tm->tm_mday = datetime.date.day;
-    tm->tm_hour = datetime.time.hour;
-    tm->tm_min  = datetime.time.min;
-    tm->tm_sec  = datetime.time.sec;
+    uint64_t ticks_s = port_get_raw_ticks(NULL) / 1024;
+    timeutils_seconds_since_2000_to_struct_time(rtc_offset + ticks_s, tm);
 }
 
 void common_hal_rtc_set_time(timeutils_struct_time_t *tm) {
-    // Reset prescaler to increase initial precision. Otherwise we can be up to 1 second off already.
-    uint32_t freqcorr = hri_rtcmode0_read_FREQCORR_reg(calendar.device.hw);
-    calendar_deinit(&calendar);
-    rtc_init();
-    hri_rtcmode0_write_FREQCORR_reg(calendar.device.hw, freqcorr);
-
-    struct calendar_date date = {
-        .year = tm->tm_year,
-        .month = tm->tm_mon,
-        .day = tm->tm_mday,
-    };
-    calendar_set_date(&calendar, &date);
-
-    struct calendar_time time = {
-        .hour = tm->tm_hour,
-        .min = tm->tm_min,
-        .sec = tm->tm_sec,
-    };
-    calendar_set_time(&calendar, &time);
+    uint64_t ticks_s = port_get_raw_ticks(NULL) / 1024;
+    uint32_t epoch_s = timeutils_seconds_since_2000(
+        tm->tm_year, tm->tm_mon, tm->tm_mday, tm->tm_hour, tm->tm_min, tm->tm_sec
+    );
+    rtc_offset = epoch_s - ticks_s;
 }
 
 // A positive value speeds up the clock by removing clock cycles.
 int common_hal_rtc_get_calibration(void) {
-    int calibration = hri_rtcmode0_read_FREQCORR_VALUE_bf(calendar.device.hw);
+    int calibration = hri_rtcmode0_read_FREQCORR_VALUE_bf(RTC);
 
-    if (!hri_rtcmode0_get_FREQCORR_SIGN_bit(calendar.device.hw))
+    if (!hri_rtcmode0_get_FREQCORR_SIGN_bit(RTC)) {
         calibration = -calibration;
+    }
 
     return calibration;
 }
 
 void common_hal_rtc_set_calibration(int calibration) {
-    if (calibration > 127 || calibration < -127)
+    if (calibration > 127 || calibration < -127) {
         mp_raise_ValueError(translate("calibration value out of range +/-127"));
+    }
 
-    hri_rtcmode0_write_FREQCORR_SIGN_bit(calendar.device.hw, calibration < 0 ? 0 : 1);
-    hri_rtcmode0_write_FREQCORR_VALUE_bf(calendar.device.hw, abs(calibration));
+    hri_rtcmode0_write_FREQCORR_SIGN_bit(RTC, calibration < 0 ? 0 : 1);
+    hri_rtcmode0_write_FREQCORR_VALUE_bf(RTC, abs(calibration));
 }
diff --git a/ports/atmel-samd/common-hal/rtc/RTC.h b/ports/atmel-samd/common-hal/rtc/RTC.h
index 1d63b2dea..19cbc0b5c 100644
--- a/ports/atmel-samd/common-hal/rtc/RTC.h
+++ b/ports/atmel-samd/common-hal/rtc/RTC.h
@@ -27,6 +27,4 @@
 #ifndef MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_RTC_RTC_H
 #define MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_RTC_RTC_H
 
-extern void rtc_init(void);
-
 #endif  // MICROPY_INCLUDED_ATMEL_SAMD_COMMON_HAL_RTC_RTC_H
diff --git a/ports/atmel-samd/common-hal/time/__init__.c b/ports/atmel-samd/common-hal/time/__init__.c
deleted file mode 100644
index 652e455fc..000000000
--- a/ports/atmel-samd/common-hal/time/__init__.c
+++ /dev/null
@@ -1,48 +0,0 @@
-/*
- * This file is part of the MicroPython project, http://micropython.org/
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2016 Scott Shawcroft for Adafruit Industries
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-#include "py/mphal.h"
-
-#include "shared-bindings/time/__init__.h"
-
-#include "supervisor/shared/tick.h"
-#include "tick.h"
-
-inline uint64_t common_hal_time_monotonic(void) {
-    return supervisor_ticks_ms64();
-}
-
-uint64_t common_hal_time_monotonic_ns(void) {
-    uint64_t ms;
-    uint32_t us_until_ms;
-    current_tick(&ms, &us_until_ms);
-    // us counts down.
-    return 1000 * (ms * 1000 + (1000 - us_until_ms));
-}
-
-void common_hal_time_delay_ms(uint32_t delay) {
-    mp_hal_delay_ms(delay);
-}
diff --git a/ports/atmel-samd/mphalport.c b/ports/atmel-samd/mphalport.c
index 96433d729..23a9b4330 100644
--- a/ports/atmel-samd/mphalport.c
+++ b/ports/atmel-samd/mphalport.c
@@ -49,21 +49,6 @@
 
 extern uint32_t common_hal_mcu_processor_get_frequency(void);
 
-void mp_hal_delay_ms(mp_uint_t delay) {
-    uint64_t start_tick = supervisor_ticks_ms64();
-    uint64_t duration = 0;
-    while (duration < delay) {
-        RUN_BACKGROUND_TASKS;
-        // Check to see if we've been CTRL-Ced by autoreload or the user.
-        if(MP_STATE_VM(mp_pending_exception) == MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_kbd_exception)) ||
-           MP_STATE_VM(mp_pending_exception) == MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_reload_exception))) {
-            break;
-        }
-        duration = (supervisor_ticks_ms64() - start_tick);
-        // TODO(tannewt): Go to sleep for a little while while we wait.
-    }
-}
-
 // Use mp_hal_delay_us() for timing of less than 1ms.
 // Do a simple timing loop to wait for a certain number of microseconds.
 // Can be used when interrupts are disabled, which makes tick_delay() unreliable.
diff --git a/ports/atmel-samd/supervisor/port.c b/ports/atmel-samd/supervisor/port.c
index 01ca797ca..61f23a791 100644
--- a/ports/atmel-samd/supervisor/port.c
+++ b/ports/atmel-samd/supervisor/port.c
@@ -70,10 +70,10 @@
 #include "samd/dma.h"
 #include "shared-bindings/rtc/__init__.h"
 #include "reset.h"
-#include "tick.h"
 
 #include "supervisor/shared/safe_mode.h"
 #include "supervisor/shared/stack.h"
+#include "supervisor/shared/tick.h"
 
 #include "tusb.h"
 
@@ -132,6 +132,38 @@ static void save_usb_clock_calibration(void) {
 }
 #endif
 
+static void rtc_init(void) {
+#ifdef SAMD21
+    _gclk_enable_channel(RTC_GCLK_ID, CONF_GCLK_RTC_SRC);
+#endif
+#ifdef SAMD51
+    hri_mclk_set_APBAMASK_RTC_bit(MCLK);
+#endif
+
+    RTC->MODE0.CTRLA.reg = RTC_MODE0_CTRLA_ENABLE |
+                     RTC_MODE0_CTRLA_MODE_COUNT32 |
+                     RTC_MODE0_CTRLA_PRESCALER_DIV2 |
+                     RTC_MODE0_CTRLA_COUNTSYNC;
+    RTC->MODE0.INTENSET.reg = RTC_MODE0_INTENSET_OVF;
+
+    // Set all peripheral interrupt priorities to the lowest priority by default.
+    for (uint16_t i = 0; i < PERIPH_COUNT_IRQn; i++) {
+        NVIC_SetPriority(i, (1UL << __NVIC_PRIO_BITS) - 1UL);
+    }
+    // Bump up the rtc interrupt so nothing else interferes with timekeeping.
+    NVIC_SetPriority(RTC_IRQn, 0);
+    #ifdef SAMD21
+    NVIC_SetPriority(USB_IRQn, 1);
+    #endif
+
+    #ifdef SAMD51
+    NVIC_SetPriority(USB_0_IRQn, 1);
+    NVIC_SetPriority(USB_1_IRQn, 1);
+    NVIC_SetPriority(USB_2_IRQn, 1);
+    NVIC_SetPriority(USB_3_IRQn, 1);
+    #endif
+}
+
 safe_mode_t port_init(void) {
 #if defined(SAMD21)
 
@@ -220,12 +252,7 @@ safe_mode_t port_init(void) {
     clock_init(BOARD_HAS_CRYSTAL, DEFAULT_DFLL48M_FINE_CALIBRATION);
 #endif
 
-    // Configure millisecond timer initialization.
-    tick_init();
-
-#if CIRCUITPY_RTC
     rtc_init();
-#endif
 
     init_shared_dma();
 
@@ -275,9 +302,6 @@ void reset_port(void) {
     analogin_reset();
     analogout_reset();
 #endif
-#if CIRCUITPY_RTC
-    rtc_reset();
-#endif
 
     reset_gclks();
 
@@ -352,6 +376,70 @@ uint32_t port_get_saved_word(void) {
     return *safe_word;
 }
 
+// TODO: Move this to an RTC backup register so we can preserve it when only the BACKUP power domain
+// is enabled.
+static volatile uint64_t overflowed_ticks = 0;
+
+void RTC_Handler(void) {
+    uint32_t intflag = RTC->MODE0.INTFLAG.reg;
+    if (intflag & RTC_MODE0_INTFLAG_OVF) {
+        RTC->MODE0.INTFLAG.reg = RTC_MODE0_INTFLAG_OVF;
+        // Our RTC is 32 bits and we're clocking it at 16.384khz which is 16 (2 ** 4) subticks per
+        // tick.
+        overflowed_ticks += (1L<< (32 - 4));
+
+    } else if (intflag & RTC_MODE0_INTFLAG_PER2) {
+        RTC->MODE0.INTFLAG.reg = RTC_MODE0_INTFLAG_PER2;
+        // Do things common to all ports when the tick occurs
+        supervisor_tick();
+    } else if (intflag & RTC_MODE0_INTFLAG_CMP0) {
+        RTC->MODE0.INTENCLR.reg = RTC_MODE0_INTENCLR_CMP0;
+        RTC->MODE0.INTFLAG.reg = RTC_MODE0_INTFLAG_CMP0;
+    }
+}
+
+uint64_t port_get_raw_ticks(uint8_t* subticks) {
+    while ((RTC->MODE0.SYNCBUSY.reg & (RTC_MODE0_SYNCBUSY_COUNTSYNC | RTC_MODE0_SYNCBUSY_COUNT)) != 0) {}
+    uint32_t current_ticks = RTC->MODE0.COUNT.reg;
+    if (subticks != NULL) {
+        *subticks = (current_ticks % 16) * 2;
+    }
+
+    return overflowed_ticks + current_ticks / 16;
+}
+
+// Enable 1/1024 second tick.
+void port_enable_tick(void) {
+    // PER2 will generate an interrupt every 32 ticks of the source 32.768 clock.
+    RTC->MODE0.INTENSET.reg = RTC_MODE0_INTFLAG_PER2;
+}
+
+// Disable 1/1024 second tick.
+void port_disable_tick(void) {
+    RTC->MODE0.INTENCLR.reg = RTC_MODE0_INTFLAG_PER2;
+}
+
+void port_interrupt_after_ticks(uint32_t ticks) {
+    while ((RTC->MODE0.SYNCBUSY.reg & (RTC_MODE0_SYNCBUSY_COUNTSYNC | RTC_MODE0_SYNCBUSY_COUNT)) != 0) {}
+    uint32_t current_ticks = RTC->MODE0.COUNT.reg;
+    if (ticks > 1 << 28) {
+        // We'll interrupt sooner with an overflow.
+        return;
+    }
+    RTC->MODE0.COMP[0].reg = current_ticks + (ticks << 4);
+    RTC->MODE0.INTENSET.reg = RTC_MODE0_INTENSET_CMP0;
+}
+
+void port_sleep_until_interrupt(void) {
+    // Clear the FPU interrupt because it can prevent us from sleeping.
+    if (__get_FPSCR()  & ~(0x9f)) {
+        __set_FPSCR(__get_FPSCR()  & ~(0x9f));
+        (void) __get_FPSCR();
+    }
+    // Call wait for interrupt ourselves if the SD isn't enabled.
+    __WFI();
+}
+
 /**
  * \brief Default interrupt handler for unused IRQs.
  */
diff --git a/ports/atmel-samd/tick.c b/ports/atmel-samd/tick.c
deleted file mode 100644
index f996440ae..000000000
--- a/ports/atmel-samd/tick.c
+++ /dev/null
@@ -1,107 +0,0 @@
-/*
- * This file is part of the MicroPython project, http://micropython.org/
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-
-#include "tick.h"
-
-#include "peripheral_clk_config.h"
-
-#include "supervisor/shared/tick.h"
-#include "shared-bindings/microcontroller/__init__.h"
-#include "shared-bindings/microcontroller/Processor.h"
-
-void SysTick_Handler(void) {
-    // SysTick interrupt handler called when the SysTick timer reaches zero
-    // (every millisecond).
-    common_hal_mcu_disable_interrupts();
-
-    // Read the control register to reset the COUNTFLAG.
-    (void) SysTick->CTRL;
-    common_hal_mcu_enable_interrupts();
-
-    // Do things common to all ports when the tick occurs
-    supervisor_tick();
-}
-
-void tick_init() {
-    uint32_t ticks_per_ms = common_hal_mcu_processor_get_frequency() / 1000;
-    SysTick_Config(ticks_per_ms-1);
-    NVIC_EnableIRQ(SysTick_IRQn);
-    // Set all peripheral interrupt priorities to the lowest priority by default.
-    for (uint16_t i = 0; i < PERIPH_COUNT_IRQn; i++) {
-        NVIC_SetPriority(i, (1UL << __NVIC_PRIO_BITS) - 1UL);
-    }
-    // Bump up the systick interrupt so nothing else interferes with timekeeping.
-    NVIC_SetPriority(SysTick_IRQn, 0);
-    #ifdef SAMD21
-    NVIC_SetPriority(USB_IRQn, 1);
-    #endif
-
-    #ifdef SAMD51
-    NVIC_SetPriority(USB_0_IRQn, 1);
-    NVIC_SetPriority(USB_1_IRQn, 1);
-    NVIC_SetPriority(USB_2_IRQn, 1);
-    NVIC_SetPriority(USB_3_IRQn, 1);
-    #endif
-}
-
-void tick_delay(uint32_t us) {
-    uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
-    uint32_t us_until_next_tick = SysTick->VAL / ticks_per_us;
-    uint32_t start_tick;
-    while (us >= us_until_next_tick) {
-        start_tick = SysTick->VAL;  // wait for SysTick->VAL to  RESET
-        while (SysTick->VAL < start_tick) {}
-        us -= us_until_next_tick;
-        us_until_next_tick = 1000;
-    }
-    while (SysTick->VAL > ((us_until_next_tick - us) * ticks_per_us)) {}
-}
-
-// us counts down!
-void current_tick(uint64_t* ms, uint32_t* us_until_ms) {
-    uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
-
-    // We disable interrupts to prevent ticks_ms from changing while we grab it.
-    common_hal_mcu_disable_interrupts();
-    uint32_t tick_status = SysTick->CTRL;
-    uint32_t current_us = SysTick->VAL;
-    uint32_t tick_status2 = SysTick->CTRL;
-    uint64_t current_ms = supervisor_ticks_ms64();
-    // The second clause ensures our value actually rolled over. Its possible it hit zero between
-    // the VAL read and CTRL read.
-    if ((tick_status & SysTick_CTRL_COUNTFLAG_Msk) != 0 ||
-        ((tick_status2 & SysTick_CTRL_COUNTFLAG_Msk) != 0 && current_us > ticks_per_us)) {
-        current_ms++;
-    }
-    common_hal_mcu_enable_interrupts();
-    *ms = current_ms;
-    *us_until_ms = current_us / ticks_per_us;
-}
-
-void wait_until(uint64_t ms, uint32_t us_until_ms) {
-    uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
-    while (supervisor_ticks_ms64() <= ms && SysTick->VAL / ticks_per_us >= us_until_ms) {}
-}
diff --git a/ports/atmel-samd/tick.h b/ports/atmel-samd/tick.h
deleted file mode 100644
index 334352df2..000000000
--- a/ports/atmel-samd/tick.h
+++ /dev/null
@@ -1,42 +0,0 @@
-/*
- * This file is part of the MicroPython project, http://micropython.org/
- *
- * The MIT License (MIT)
- *
- * Copyright (c) 2017 Scott Shawcroft for Adafruit Industries
- *
- * Permission is hereby granted, free of charge, to any person obtaining a copy
- * of this software and associated documentation files (the "Software"), to deal
- * in the Software without restriction, including without limitation the rights
- * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
- * copies of the Software, and to permit persons to whom the Software is
- * furnished to do so, subject to the following conditions:
- *
- * The above copyright notice and this permission notice shall be included in
- * all copies or substantial portions of the Software.
- *
- * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
- * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
- * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
- * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
- * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
- * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
- * THE SOFTWARE.
- */
-#ifndef MICROPY_INCLUDED_ATMEL_SAMD_TICK_H
-#define MICROPY_INCLUDED_ATMEL_SAMD_TICK_H
-
-#include "py/mpconfig.h"
-
-extern struct timer_descriptor ms_timer;
-
-void tick_init(void);
-
-void tick_delay(uint32_t us);
-
-void current_tick(uint64_t* ms, uint32_t* us_until_ms);
-// Do not call this with interrupts disabled because it may be waiting for
-// ticks_ms to increment.
-void wait_until(uint64_t ms, uint32_t us_until_ms);
-
-#endif  // MICROPY_INCLUDED_ATMEL_SAMD_TICK_H
diff --git a/ports/nrf/common-hal/rtc/RTC.c b/ports/nrf/common-hal/rtc/RTC.c
index 6b582ef26..9f56f2f0d 100644
--- a/ports/nrf/common-hal/rtc/RTC.c
+++ b/ports/nrf/common-hal/rtc/RTC.c
@@ -33,9 +33,6 @@
 #include "supervisor/port.h"
 #include "supervisor/shared/translate.h"
 
-#include "nrfx_rtc.h"
-#include "nrf_clock.h"
-
 // This is the time in seconds since 2000 that the RTC was started.
 static uint32_t rtc_offset = 0;
 
diff --git a/ports/nrf/supervisor/port.c b/ports/nrf/supervisor/port.c
index 2a4604091..17e980dff 100644
--- a/ports/nrf/supervisor/port.c
+++ b/ports/nrf/supervisor/port.c
@@ -78,7 +78,9 @@ static volatile uint64_t overflowed_ticks = 0;
 
 void rtc_handler(nrfx_rtc_int_type_t int_type) {
     if (int_type == NRFX_RTC_INT_OVERFLOW) {
-        overflowed_ticks += (1L<<24);
+        // Our RTC is 24 bits and we're clocking it at 32.768khz which is 32 (2 ** 5) subticks per
+        // tick.
+        overflowed_ticks += (1L<< (24 - 5));
     } else if (int_type == NRFX_RTC_INT_TICK && nrfx_rtc_counter_get(&rtc_instance) % 32 == 0) {
         // Do things common to all ports when the tick occurs
         supervisor_tick();
diff --git a/py/circuitpy_defns.mk b/py/circuitpy_defns.mk
index 92021d0d0..135782cf4 100644
--- a/py/circuitpy_defns.mk
+++ b/py/circuitpy_defns.mk
@@ -282,8 +282,7 @@ SRC_COMMON_HAL_ALL = \
 	rtc/RTC.c \
 	rtc/__init__.c \
 	supervisor/Runtime.c \
-	supervisor/__init__.c \
-	time/__init__.c
+	supervisor/__init__.c
 
 SRC_COMMON_HAL = $(filter $(SRC_PATTERNS), $(SRC_COMMON_HAL_ALL))
 
@@ -358,13 +357,14 @@ SRC_SHARED_MODULE_ALL = \
 	network/__init__.c \
 	storage/__init__.c \
 	struct/__init__.c \
+	time/__init__.c \
 	terminalio/Terminal.c \
 	terminalio/__init__.c \
 	uheap/__init__.c \
 	ustack/__init__.c \
 	_pew/__init__.c \
 	_pew/PewPew.c \
-        _eve/__init__.c
+    _eve/__init__.c
 
 # All possible sources are listed here, and are filtered by SRC_PATTERNS.
 SRC_SHARED_MODULE = $(filter $(SRC_PATTERNS), $(SRC_SHARED_MODULE_ALL))
diff --git a/ports/nrf/common-hal/time/__init__.c b/shared-module/time/__init__.c
index 21fe98926..21fe98926 100644
--- a/ports/nrf/common-hal/time/__init__.c
+++ b/shared-module/time/__init__.c