diff --git a/drivers/wiznet5k/internet/dns/dns.c b/drivers/wiznet5k/internet/dns/dns.c
index daf4db1230..8b9e966708 100644
--- a/drivers/wiznet5k/internet/dns/dns.c
+++ b/drivers/wiznet5k/internet/dns/dns.c
@@ -52,7 +52,7 @@
 
 #include <string.h>
 #include <stdlib.h>
-#include "tick.h"
+#include "supervisor/shared/tick.h"
 
 //#include "Ethernet/socket.h"
 //#include "Internet/DNS/dns.h"
@@ -125,7 +125,7 @@ uint16_t DNS_MSGID;     // DNS message ID
 
 
 uint32_t HAL_GetTick(void) {
-    return ticks_ms;
+    return supervisor_ticks_ms32();
 }
 
 uint32_t hal_sys_tick;
diff --git a/ports/atmel-samd/background.c b/ports/atmel-samd/background.c
index 386ba07158..ca91a31de6 100644
--- a/ports/atmel-samd/background.c
+++ b/ports/atmel-samd/background.c
@@ -28,6 +28,7 @@
 #include "audio_dma.h"
 #include "tick.h"
 #include "supervisor/filesystem.h"
+#include "supervisor/shared/tick.h"
 #include "supervisor/usb.h"
 
 #include "py/runtime.h"
@@ -44,6 +45,23 @@ bool stack_ok_so_far = true;
 
 static bool running_background_tasks = false;
 
+#ifdef MONITOR_BACKGROUND_TASKS
+// PB03 is physical pin "SCL" on the Metro M4 express
+// so you can't use this code AND an i2c peripheral
+// at the same time unless you change this
+STATIC void start_background_task(void) {
+    REG_PORT_DIRSET1 = (1<<3);
+    REG_PORT_OUTSET1 = (1<<3);
+}
+
+STATIC void finish_background_task(void) {
+    REG_PORT_OUTCLR1 = (1<<3);
+}
+#else
+STATIC void start_background_task(void) {}
+STATIC void finish_background_task(void) {}
+#endif
+
 void background_tasks_reset(void) {
     running_background_tasks = false;
 }
@@ -53,6 +71,9 @@ void run_background_tasks(void) {
     if (running_background_tasks) {
         return;
     }
+
+    start_background_task();
+
     assert_heap_ok();
     running_background_tasks = true;
 
@@ -71,9 +92,10 @@ void run_background_tasks(void) {
     running_background_tasks = false;
     assert_heap_ok();
 
-    last_finished_tick = ticks_ms;
+    last_finished_tick = supervisor_ticks_ms64();
+    finish_background_task();
 }
 
 bool background_tasks_ok(void) {
-    return ticks_ms - last_finished_tick < 1000;
+    return supervisor_ticks_ms64() - last_finished_tick < 1000;
 }
diff --git a/ports/atmel-samd/common-hal/busio/UART.c b/ports/atmel-samd/common-hal/busio/UART.c
index d869f70ff4..4ad47a58da 100644
--- a/ports/atmel-samd/common-hal/busio/UART.c
+++ b/ports/atmel-samd/common-hal/busio/UART.c
@@ -34,8 +34,7 @@
 #include "py/runtime.h"
 #include "py/stream.h"
 #include "supervisor/shared/translate.h"
-
-#include "tick.h"
+#include "supervisor/shared/tick.h"
 
 #include "hpl_sercom_config.h"
 #include "peripheral_clk_config.h"
@@ -272,10 +271,10 @@ size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t
     usart_async_get_io_descriptor(usart_desc_p, &io);
 
     size_t total_read = 0;
-    uint64_t start_ticks = ticks_ms;
+    uint64_t start_ticks = supervisor_ticks_ms64();
 
     // Busy-wait until timeout or until we've read enough chars.
-    while (ticks_ms - start_ticks <= self->timeout_ms) {
+    while (supervisor_ticks_ms64() - start_ticks <= self->timeout_ms) {
         // Read as many chars as we can right now, up to len.
         size_t num_read = io_read(io, data, len);
 
@@ -289,7 +288,7 @@ size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t
         }
         if (num_read > 0) {
             // Reset the timeout on every character read.
-            start_ticks = ticks_ms;
+            start_ticks = supervisor_ticks_ms64();
         }
         RUN_BACKGROUND_TASKS;
         // Allow user to break out of a timeout with a KeyboardInterrupt.
diff --git a/ports/atmel-samd/common-hal/time/__init__.c b/ports/atmel-samd/common-hal/time/__init__.c
index 0d60adef20..2d82b3d1ad 100644
--- a/ports/atmel-samd/common-hal/time/__init__.c
+++ b/ports/atmel-samd/common-hal/time/__init__.c
@@ -28,10 +28,10 @@
 
 #include "shared-bindings/time/__init__.h"
 
-#include "tick.h"
+#include "supervisor/shared/tick.h"
 
 inline uint64_t common_hal_time_monotonic() {
-    return ticks_ms;
+    return supervisor_ticks_ms64();
 }
 
 void common_hal_time_delay_ms(uint32_t delay) {
diff --git a/ports/atmel-samd/mphalport.c b/ports/atmel-samd/mphalport.c
index 957bf6073e..96433d729f 100644
--- a/ports/atmel-samd/mphalport.c
+++ b/ports/atmel-samd/mphalport.c
@@ -45,12 +45,12 @@
 #include "mpconfigboard.h"
 #include "mphalport.h"
 #include "reset.h"
-#include "tick.h"
+#include "supervisor/shared/tick.h"
 
 extern uint32_t common_hal_mcu_processor_get_frequency(void);
 
 void mp_hal_delay_ms(mp_uint_t delay) {
-    uint64_t start_tick = ticks_ms;
+    uint64_t start_tick = supervisor_ticks_ms64();
     uint64_t duration = 0;
     while (duration < delay) {
         RUN_BACKGROUND_TASKS;
@@ -59,7 +59,7 @@ void mp_hal_delay_ms(mp_uint_t delay) {
            MP_STATE_VM(mp_pending_exception) == MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_reload_exception))) {
             break;
         }
-        duration = (ticks_ms - start_tick);
+        duration = (supervisor_ticks_ms64() - start_tick);
         // TODO(tannewt): Go to sleep for a little while while we wait.
     }
 }
diff --git a/ports/atmel-samd/mphalport.h b/ports/atmel-samd/mphalport.h
index 64269b201f..8a762e2584 100644
--- a/ports/atmel-samd/mphalport.h
+++ b/ports/atmel-samd/mphalport.h
@@ -31,11 +31,11 @@
 
 #include "lib/oofatfs/ff.h"
 
-// Global millisecond tick count (driven by SysTick interrupt).
-extern volatile uint64_t ticks_ms;
+#include "supervisor/shared/tick.h"
 
+// Global millisecond tick count (driven by SysTick interrupt).
 static inline mp_uint_t mp_hal_ticks_ms(void) {
-  return ticks_ms;
+  return supervisor_ticks_ms32();
 }
 // Number of bytes in receive buffer
 volatile uint8_t usb_rx_count;
diff --git a/ports/atmel-samd/tick.c b/ports/atmel-samd/tick.c
index 4d7bb9dca7..f996440ae3 100644
--- a/ports/atmel-samd/tick.c
+++ b/ports/atmel-samd/tick.c
@@ -28,47 +28,21 @@
 
 #include "peripheral_clk_config.h"
 
-#include "supervisor/shared/autoreload.h"
-#include "supervisor/filesystem.h"
+#include "supervisor/shared/tick.h"
 #include "shared-bindings/microcontroller/__init__.h"
 #include "shared-bindings/microcontroller/Processor.h"
 
-#if CIRCUITPY_GAMEPAD
-#include "shared-module/gamepad/__init__.h"
-#endif
-
-#if CIRCUITPY_GAMEPADSHIFT
-#include "shared-module/gamepadshift/__init__.h"
-#endif
-// Global millisecond tick count
-volatile uint64_t ticks_ms = 0;
-
 void SysTick_Handler(void) {
     // SysTick interrupt handler called when the SysTick timer reaches zero
     // (every millisecond).
     common_hal_mcu_disable_interrupts();
-    ticks_ms += 1;
 
     // Read the control register to reset the COUNTFLAG.
     (void) SysTick->CTRL;
     common_hal_mcu_enable_interrupts();
 
-#if CIRCUITPY_FILESYSTEM_FLUSH_INTERVAL_MS > 0
-    filesystem_tick();
-#endif
-#ifdef CIRCUITPY_AUTORELOAD_DELAY_MS
-        autoreload_tick();
-#endif
-#ifdef CIRCUITPY_GAMEPAD_TICKS
-    if (!(ticks_ms & CIRCUITPY_GAMEPAD_TICKS)) {
-        #if CIRCUITPY_GAMEPAD
-        gamepad_tick();
-        #endif
-        #if CIRCUITPY_GAMEPADSHIFT
-        gamepadshift_tick();
-        #endif
-    }
-#endif
+    // Do things common to all ports when the tick occurs
+    supervisor_tick();
 }
 
 void tick_init() {
@@ -115,7 +89,7 @@ void current_tick(uint64_t* ms, uint32_t* us_until_ms) {
     uint32_t tick_status = SysTick->CTRL;
     uint32_t current_us = SysTick->VAL;
     uint32_t tick_status2 = SysTick->CTRL;
-    uint64_t current_ms = ticks_ms;
+    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 ||
@@ -129,5 +103,5 @@ void current_tick(uint64_t* ms, uint32_t* us_until_ms) {
 
 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 (ticks_ms <= ms && SysTick->VAL / ticks_per_us >= us_until_ms) {}
+    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
index c8c8d739ab..334352df26 100644
--- a/ports/atmel-samd/tick.h
+++ b/ports/atmel-samd/tick.h
@@ -28,8 +28,6 @@
 
 #include "py/mpconfig.h"
 
-extern volatile uint64_t ticks_ms;
-
 extern struct timer_descriptor ms_timer;
 
 void tick_init(void);
diff --git a/ports/cxd56/common-hal/time/__init__.c b/ports/cxd56/common-hal/time/__init__.c
index 8f7326b629..6f5eedd419 100644
--- a/ports/cxd56/common-hal/time/__init__.c
+++ b/ports/cxd56/common-hal/time/__init__.c
@@ -26,10 +26,10 @@
 
 #include "py/mphal.h"
 
-#include "tick.h"
+#include "supervisor/shared/tick.h"
 
 uint64_t common_hal_time_monotonic(void) {
-    return ticks_ms;
+    return supervisor_ticks_ms64();
 }
 
 void common_hal_time_delay_ms(uint32_t delay) {
diff --git a/ports/cxd56/mphalport.c b/ports/cxd56/mphalport.c
index 79d93f9759..1305706caa 100644
--- a/ports/cxd56/mphalport.c
+++ b/ports/cxd56/mphalport.c
@@ -31,7 +31,7 @@
 
 #include "py/mpstate.h"
 
-#include "tick.h"
+#include "supervisor/shared/tick.h"
 
 #define DELAY_CORRECTION    (700)
 #define DELAY_INTERVAL      (50)
@@ -57,7 +57,7 @@ mp_uint_t mp_hal_ticks_cpu(void) {
 }
 
 void mp_hal_delay_ms(mp_uint_t delay) {
-    uint64_t start_tick = ticks_ms;
+    uint64_t start_tick = supervisor_ticks_ms64();
     uint64_t duration = 0;
     while (duration < delay) {
         #ifdef MICROPY_VM_HOOK_LOOP
@@ -68,7 +68,7 @@ void mp_hal_delay_ms(mp_uint_t delay) {
            MP_STATE_VM(mp_pending_exception) == MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_reload_exception))) {
             break;
         }
-        duration = (ticks_ms - start_tick);
+        duration = (supervisor_ticks_ms64() - start_tick);
         // TODO(tannewt): Go to sleep for a little while while we wait.
     }
 }
diff --git a/ports/cxd56/mphalport.h b/ports/cxd56/mphalport.h
index 25bca97ad7..a2be10b8d0 100644
--- a/ports/cxd56/mphalport.h
+++ b/ports/cxd56/mphalport.h
@@ -31,6 +31,4 @@
 
 #include "lib/utils/interrupt_char.h"
 
-extern volatile uint64_t ticks_ms;
-
 #endif // MICROPY_INCLUDED_CXD56_MPHALPORT_H
diff --git a/ports/cxd56/tick.c b/ports/cxd56/tick.c
index 6529db7901..671b82b744 100644
--- a/ports/cxd56/tick.c
+++ b/ports/cxd56/tick.c
@@ -27,19 +27,10 @@
 #include "tick.h"
 
 #include "supervisor/shared/autoreload.h"
-#include "supervisor/filesystem.h"
-
-// Global millisecond tick count
-volatile uint64_t ticks_ms = 0;
+#include "supervisor/shared/tick.h"
 
 void board_timerhook(void)
 {
-    ticks_ms += 1;
-
-#if CIRCUITPY_FILESYSTEM_FLUSH_INTERVAL_MS > 0
-    filesystem_tick();
-#endif
-#ifdef CIRCUITPY_AUTORELOAD_DELAY_MS
-    autoreload_tick();
-#endif
+    // Do things common to all ports when the tick occurs
+    supervisor_tick();
 }
diff --git a/ports/cxd56/tick.h b/ports/cxd56/tick.h
index a0d9ee5263..d641d9cd4f 100644
--- a/ports/cxd56/tick.h
+++ b/ports/cxd56/tick.h
@@ -29,6 +29,4 @@
 
 #include "py/mpconfig.h"
 
-extern volatile uint64_t ticks_ms;
-
 #endif  // MICROPY_INCLUDED_CXD56_TICK_H
diff --git a/ports/nrf/common-hal/_bleio/Adapter.c b/ports/nrf/common-hal/_bleio/Adapter.c
index ec8d361115..85c159c6d5 100644
--- a/ports/nrf/common-hal/_bleio/Adapter.c
+++ b/ports/nrf/common-hal/_bleio/Adapter.c
@@ -40,6 +40,7 @@
 #include "py/objstr.h"
 #include "py/runtime.h"
 #include "supervisor/shared/safe_mode.h"
+#include "supervisor/shared/tick.h"
 #include "supervisor/usb.h"
 #include "shared-bindings/_bleio/__init__.h"
 #include "shared-bindings/_bleio/Adapter.h"
@@ -343,7 +344,7 @@ STATIC bool scan_on_ble_evt(ble_evt_t *ble_evt, void *scan_results_in) {
     ble_gap_evt_adv_report_t *report = &ble_evt->evt.gap_evt.params.adv_report;
 
     shared_module_bleio_scanresults_append(scan_results,
-                                           ticks_ms,
+                                           supervisor_ticks_ms64(),
                                            report->type.connectable,
                                            report->type.scan_response,
                                            report->rssi,
diff --git a/ports/nrf/common-hal/_bleio/CharacteristicBuffer.c b/ports/nrf/common-hal/_bleio/CharacteristicBuffer.c
index 5f280e121f..9f9b453de4 100644
--- a/ports/nrf/common-hal/_bleio/CharacteristicBuffer.c
+++ b/ports/nrf/common-hal/_bleio/CharacteristicBuffer.c
@@ -39,6 +39,7 @@
 
 #include "shared-bindings/_bleio/__init__.h"
 #include "shared-bindings/_bleio/Connection.h"
+#include "supervisor/shared/tick.h"
 #include "common-hal/_bleio/CharacteristicBuffer.h"
 
 STATIC void write_to_ringbuf(bleio_characteristic_buffer_obj_t *self, uint8_t *data, uint16_t len) {
@@ -100,10 +101,10 @@ void common_hal_bleio_characteristic_buffer_construct(bleio_characteristic_buffe
 }
 
 int common_hal_bleio_characteristic_buffer_read(bleio_characteristic_buffer_obj_t *self, uint8_t *data, size_t len, int *errcode) {
-    uint64_t start_ticks = ticks_ms;
+    uint64_t start_ticks = supervisor_ticks_ms64();
 
     // Wait for all bytes received or timeout
-    while ( (ringbuf_count(&self->ringbuf) < len) && (ticks_ms - start_ticks < self->timeout_ms) ) {
+    while ( (ringbuf_count(&self->ringbuf) < len) && (supervisor_ticks_ms64() - start_ticks < self->timeout_ms) ) {
         RUN_BACKGROUND_TASKS;
         // Allow user to break out of a timeout with a KeyboardInterrupt.
         if ( mp_hal_is_interrupted() ) {
diff --git a/ports/nrf/common-hal/busio/UART.c b/ports/nrf/common-hal/busio/UART.c
index a0ae8af00e..9cdc197e7c 100644
--- a/ports/nrf/common-hal/busio/UART.c
+++ b/ports/nrf/common-hal/busio/UART.c
@@ -231,10 +231,10 @@ size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t
     }
 
     size_t rx_bytes = 0;
-    uint64_t start_ticks = ticks_ms;
+    uint64_t start_ticks = supervisor_ticks_ms64();
 
     // Wait for all bytes received or timeout
-    while ( (ringbuf_count(&self->rbuf) < len) && (ticks_ms - start_ticks < self->timeout_ms) ) {
+    while ( (ringbuf_count(&self->rbuf) < len) && (supervisor_ticks_ms64() - start_ticks < self->timeout_ms) ) {
         RUN_BACKGROUND_TASKS;
         // Allow user to break out of a timeout with a KeyboardInterrupt.
         if ( mp_hal_is_interrupted() ) {
diff --git a/ports/nrf/common-hal/time/__init__.c b/ports/nrf/common-hal/time/__init__.c
index e3cb481ef4..976f519db2 100644
--- a/ports/nrf/common-hal/time/__init__.c
+++ b/ports/nrf/common-hal/time/__init__.c
@@ -29,7 +29,7 @@
 #include "tick.h"
 
 uint64_t common_hal_time_monotonic(void) {
-    return ticks_ms;
+    return supervisor_ticks_ms64();
 }
 
 void common_hal_time_delay_ms(uint32_t delay) {
diff --git a/ports/nrf/mphalport.c b/ports/nrf/mphalport.c
index bcd9fb1145..3885d5a826 100644
--- a/ports/nrf/mphalport.c
+++ b/ports/nrf/mphalport.c
@@ -31,12 +31,13 @@
 #include "py/mphal.h"
 #include "py/mpstate.h"
 #include "py/gc.h"
+#include "supervisor/shared/tick.h"
 
 /*------------------------------------------------------------------*/
 /* delay
  *------------------------------------------------------------------*/
 void mp_hal_delay_ms(mp_uint_t delay) {
-    uint64_t start_tick = ticks_ms;
+    uint64_t start_tick = supervisor_ticks_ms64();
     uint64_t duration = 0;
     while (duration < delay) {
         RUN_BACKGROUND_TASKS;
@@ -45,7 +46,7 @@ void mp_hal_delay_ms(mp_uint_t delay) {
            MP_STATE_VM(mp_pending_exception) == MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_reload_exception))) {
             break;
         }
-        duration = (ticks_ms - start_tick);
+        duration = (supervisor_ticks_ms64() - start_tick);
         // TODO(tannewt): Go to sleep for a little while while we wait.
     }
 }
diff --git a/ports/nrf/mphalport.h b/ports/nrf/mphalport.h
index a1929a4ace..8bb351401a 100644
--- a/ports/nrf/mphalport.h
+++ b/ports/nrf/mphalport.h
@@ -33,12 +33,11 @@
 #include "lib/utils/interrupt_char.h"
 #include "nrfx_uarte.h"
 #include "py/mpconfig.h"
+#include "supervisor/shared/tick.h"
 
 extern nrfx_uarte_t serial_instance;
 
-extern volatile uint64_t ticks_ms;
-
-#define mp_hal_ticks_ms()       ((mp_uint_t) ticks_ms)
+#define mp_hal_ticks_ms()       ((mp_uint_t) supervisor_ticks_ms32())
 #define mp_hal_delay_us(us)     NRFX_DELAY_US((uint32_t) (us))
 
 bool mp_hal_stdin_any(void);
diff --git a/ports/nrf/tick.c b/ports/nrf/tick.c
index 6d8fd13e0a..ac825a7f1f 100644
--- a/ports/nrf/tick.c
+++ b/ports/nrf/tick.c
@@ -26,31 +26,14 @@
 
 #include "tick.h"
 
-#include "supervisor/shared/autoreload.h"
-#include "supervisor/filesystem.h"
+#include "supervisor/shared/tick.h"
 #include "shared-module/gamepad/__init__.h"
 #include "shared-bindings/microcontroller/Processor.h"
 #include "nrf.h"
 
-// Global millisecond tick count
-volatile uint64_t ticks_ms = 0;
-
 void SysTick_Handler(void) {
-    // SysTick interrupt handler called when the SysTick timer reaches zero
-    // (every millisecond).
-    ticks_ms += 1;
-
-#if CIRCUITPY_FILESYSTEM_FLUSH_INTERVAL_MS > 0
-    filesystem_tick();
-#endif
-#ifdef CIRCUITPY_AUTORELOAD_DELAY_MS
-    autoreload_tick();
-#endif
-#ifdef CIRCUITPY_GAMEPAD_TICKS
-    if (!(ticks_ms & CIRCUITPY_GAMEPAD_TICKS)) {
-        gamepad_tick();
-    }
-#endif
+    // Do things common to all ports when the tick occurs
+    supervisor_tick();
 }
 
 void tick_init() {
@@ -61,11 +44,11 @@ void tick_init() {
 void tick_delay(uint32_t us) {
     uint32_t ticks_per_us = common_hal_mcu_processor_get_frequency() / 1000 / 1000;
     uint32_t us_between_ticks = SysTick->VAL / ticks_per_us;
-    uint64_t start_ms = ticks_ms;
+    uint64_t start_ms = supervisor_ticks_ms64();
     while (us > 1000) {
-        while (ticks_ms == start_ms) {}
+        while (supervisor_ticks_ms64() == start_ms) {}
         us -= us_between_ticks;
-        start_ms = ticks_ms;
+        start_ms = supervisor_ticks_ms64();
         us_between_ticks = 1000;
     }
     while (SysTick->VAL > ((us_between_ticks - us) * ticks_per_us)) {}
@@ -74,11 +57,11 @@ void tick_delay(uint32_t 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;
-    *ms = ticks_ms;
+    *ms = supervisor_ticks_ms64();
     *us_until_ms = SysTick->VAL / 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(ticks_ms <= ms && SysTick->VAL / ticks_per_us >= us_until_ms) {}
+    while(supervisor_ticks_ms64() <= ms && SysTick->VAL / ticks_per_us >= us_until_ms) {}
 }
diff --git a/ports/nrf/tick.h b/ports/nrf/tick.h
index 838e9fbea8..d638ad0251 100644
--- a/ports/nrf/tick.h
+++ b/ports/nrf/tick.h
@@ -30,8 +30,6 @@
 
 #include <stdint.h>
 
-extern volatile uint64_t ticks_ms;
-
 extern struct timer_descriptor ms_timer;
 
 void tick_init(void);
diff --git a/ports/stm32f4/common-hal/busio/UART.c b/ports/stm32f4/common-hal/busio/UART.c
index f0e0cc9eb4..aa792dae18 100644
--- a/ports/stm32f4/common-hal/busio/UART.c
+++ b/ports/stm32f4/common-hal/busio/UART.c
@@ -250,10 +250,10 @@ size_t common_hal_busio_uart_read(busio_uart_obj_t *self, uint8_t *data, size_t
     }
 
     size_t rx_bytes = 0;
-    uint64_t start_ticks = ticks_ms;
+    uint64_t start_ticks = supervisor_ticks_ms64();
 
     // Wait for all bytes received or timeout, same as nrf
-    while ( (ringbuf_count(&self->rbuf) < len) && (ticks_ms - start_ticks < self->timeout_ms) ) {
+    while ( (ringbuf_count(&self->rbuf) < len) && (supervisor_ticks_ms64() - start_ticks < self->timeout_ms) ) {
         RUN_BACKGROUND_TASKS;
         //restart if it failed in the callback
         if (errflag != HAL_OK) {
diff --git a/ports/stm32f4/common-hal/microcontroller/__init__.c b/ports/stm32f4/common-hal/microcontroller/__init__.c
index c7493a4d60..ffab5d1e50 100644
--- a/ports/stm32f4/common-hal/microcontroller/__init__.c
+++ b/ports/stm32f4/common-hal/microcontroller/__init__.c
@@ -48,9 +48,9 @@ STATIC uint32_t get_us(void) {
     uint32_t ticks_per_us = HAL_RCC_GetSysClockFreq()/1000000;
     uint32_t micros, sys_cycles;
     do {
-        micros = ticks_ms;
+        micros = supervisor_ticks_ms32();
         sys_cycles = SysTick->VAL; //counts backwards
-    } while (micros != ticks_ms); //try again if ticks_ms rolled over
+    } while (micros != supervisor_ticks_ms32()); //try again if ticks_ms rolled over
     return (micros * 1000) + (ticks_per_us * 1000 - sys_cycles) / ticks_per_us;
 }
 
diff --git a/ports/stm32f4/common-hal/time/__init__.c b/ports/stm32f4/common-hal/time/__init__.c
index e3cb481ef4..976f519db2 100644
--- a/ports/stm32f4/common-hal/time/__init__.c
+++ b/ports/stm32f4/common-hal/time/__init__.c
@@ -29,7 +29,7 @@
 #include "tick.h"
 
 uint64_t common_hal_time_monotonic(void) {
-    return ticks_ms;
+    return supervisor_ticks_ms64();
 }
 
 void common_hal_time_delay_ms(uint32_t delay) {
diff --git a/ports/stm32f4/mphalport.c b/ports/stm32f4/mphalport.c
index ea864e7ceb..f78e9c7501 100644
--- a/ports/stm32f4/mphalport.c
+++ b/ports/stm32f4/mphalport.c
@@ -31,11 +31,13 @@
 #include "py/mpstate.h"
 #include "py/gc.h"
 
+#include "supervisor/shared/tick.h"
+
 /*------------------------------------------------------------------*/
 /* delay
  *------------------------------------------------------------------*/
 void mp_hal_delay_ms(mp_uint_t delay) {
-    uint64_t start_tick = ticks_ms;
+    uint64_t start_tick = supervisor_ticks_ms64();
     uint64_t duration = 0;
     while (duration < delay) {
         #ifdef MICROPY_VM_HOOK_LOOP
@@ -46,7 +48,7 @@ void mp_hal_delay_ms(mp_uint_t delay) {
            MP_STATE_VM(mp_pending_exception) == MP_OBJ_FROM_PTR(&MP_STATE_VM(mp_reload_exception))) {
             break;
         }
-        duration = (ticks_ms - start_tick);
+        duration = (supervisor_ticks_ms64() - start_tick);
         // TODO(tannewt): Go to sleep for a little while while we wait.
     }
 }
diff --git a/ports/stm32f4/mphalport.h b/ports/stm32f4/mphalport.h
index d184138f78..df2f0ca65a 100644
--- a/ports/stm32f4/mphalport.h
+++ b/ports/stm32f4/mphalport.h
@@ -32,10 +32,10 @@
 
 #include "lib/utils/interrupt_char.h"
 #include "py/mpconfig.h"
+#include "supervisor/shared/tick.h"
 
-extern volatile uint64_t ticks_ms;
 
-#define mp_hal_ticks_ms()       ((mp_uint_t) ticks_ms)
+#define mp_hal_ticks_ms()       ((mp_uint_t) supervisor_ticks_ms32())
 //#define mp_hal_delay_us(us)     NRFX_DELAY_US((uint32_t) (us))
 
 bool mp_hal_stdin_any(void);
diff --git a/ports/stm32f4/tick.c b/ports/stm32f4/tick.c
index 688f71dbd4..f4adf183aa 100644
--- a/ports/stm32f4/tick.c
+++ b/ports/stm32f4/tick.c
@@ -26,37 +26,23 @@
 
 #include "tick.h"
 
-#include "supervisor/shared/autoreload.h"
 #include "supervisor/filesystem.h"
-#include "shared-module/gamepad/__init__.h"
+#include "supervisor/shared/tick.h"
 #include "shared-bindings/microcontroller/Processor.h"
 
 #include "stm32f4xx.h"
 
-// Global millisecond tick count
-volatile uint64_t ticks_ms = 0;
-
 void SysTick_Handler(void) {
     // SysTick interrupt handler called when the SysTick timer reaches zero
     // (every millisecond).
-    ticks_ms += 1;
 
-#if CIRCUITPY_FILESYSTEM_FLUSH_INTERVAL_MS > 0
-    filesystem_tick();
-#endif
-#ifdef CIRCUITPY_AUTORELOAD_DELAY_MS
-    autoreload_tick();
-#endif
-#ifdef CIRCUITPY_GAMEPAD_TICKS
-    if (!(ticks_ms & CIRCUITPY_GAMEPAD_TICKS)) {
-        gamepad_tick();
-    }
-#endif
+    // Do things common to all ports when the tick occurs
+    supervisor_tick();
 }
 
 uint32_t HAL_GetTick(void) //override ST HAL
 {
-  return (uint32_t)ticks_ms;
+  return (uint32_t)supervisor_ticks_ms32();
 }
 
 void tick_init() {
@@ -72,11 +58,11 @@ void tick_init() {
 void tick_delay(uint32_t us) {
     uint32_t ticks_per_us = SystemCoreClock / 1000 / 1000;
     uint32_t us_between_ticks = SysTick->VAL / ticks_per_us;
-    uint64_t start_ms = ticks_ms;
+    uint64_t start_ms = supervisor_ticks_ms64();
     while (us > 1000) {
-        while (ticks_ms == start_ms) {}
+        while (supervisor_ticks_ms64() == start_ms) {}
         us -= us_between_ticks;
-        start_ms = ticks_ms;
+        start_ms = supervisor_ticks_ms64();
         us_between_ticks = 1000;
     }
     while (SysTick->VAL > ((us_between_ticks - us) * ticks_per_us)) {}
@@ -85,11 +71,11 @@ void tick_delay(uint32_t us) {
 // us counts down!
 void current_tick(uint64_t* ms, uint32_t* us_until_ms) {
     uint32_t ticks_per_us = SystemCoreClock / 1000 / 1000;
-    *ms = ticks_ms;
+    *ms = supervisor_ticks_ms32();
     *us_until_ms = SysTick->VAL / ticks_per_us;
 }
 
 void wait_until(uint64_t ms, uint32_t us_until_ms) {
     uint32_t ticks_per_us = SystemCoreClock / 1000 / 1000;
-    while(ticks_ms <= ms && SysTick->VAL / ticks_per_us >= us_until_ms) {}
+    while(supervisor_ticks_ms64() <= ms && SysTick->VAL / ticks_per_us >= us_until_ms) {}
 }
diff --git a/ports/stm32f4/tick.h b/ports/stm32f4/tick.h
index e4772fa2cf..999acc7a3c 100644
--- a/ports/stm32f4/tick.h
+++ b/ports/stm32f4/tick.h
@@ -30,8 +30,6 @@
 
 #include <stdint.h>
 
-extern volatile uint64_t ticks_ms;
-
 extern struct timer_descriptor ms_timer;
 
 void tick_init(void);
diff --git a/py/circuitpy_mpconfig.h b/py/circuitpy_mpconfig.h
index b1e7bc05aa..3e83d0c510 100644
--- a/py/circuitpy_mpconfig.h
+++ b/py/circuitpy_mpconfig.h
@@ -28,11 +28,12 @@
 // sure that the same feature set and settings are used, such as in atmel-samd
 // and nrf.
 
-#include <stdint.h>
-
 #ifndef __INCLUDED_MPCONFIG_CIRCUITPY_H
 #define __INCLUDED_MPCONFIG_CIRCUITPY_H
 
+#include <stdint.h>
+#include <stdatomic.h>
+
 // This is CircuitPython.
 #define CIRCUITPY 1
 
@@ -652,14 +653,14 @@ extern const struct _mp_obj_module_t ustack_module;
     FLASH_ROOT_POINTERS \
     NETWORK_ROOT_POINTERS \
 
-void run_background_tasks(void);
-#define RUN_BACKGROUND_TASKS (run_background_tasks())
+void supervisor_run_background_tasks_if_tick(void);
+#define RUN_BACKGROUND_TASKS (supervisor_run_background_tasks_if_tick())
 
 // TODO: Used in wiznet5k driver, but may not be needed in the long run.
 #define MICROPY_THREAD_YIELD()
 
-#define MICROPY_VM_HOOK_LOOP run_background_tasks();
-#define MICROPY_VM_HOOK_RETURN run_background_tasks();
+#define MICROPY_VM_HOOK_LOOP RUN_BACKGROUND_TASKS;
+#define MICROPY_VM_HOOK_RETURN RUN_BACKGROUND_TASKS;
 
 #define CIRCUITPY_AUTORELOAD_DELAY_MS 500
 #define CIRCUITPY_FILESYSTEM_FLUSH_INTERVAL_MS 1000
diff --git a/shared-module/displayio/Display.c b/shared-module/displayio/Display.c
index 862d2cf598..11db0f8ff2 100644
--- a/shared-module/displayio/Display.c
+++ b/shared-module/displayio/Display.c
@@ -35,6 +35,7 @@
 #include "shared-module/displayio/__init__.h"
 #include "shared-module/displayio/display_core.h"
 #include "supervisor/shared/display.h"
+#include "supervisor/shared/tick.h"
 #include "supervisor/usb.h"
 
 #include <stdint.h>
@@ -313,7 +314,7 @@ uint16_t common_hal_displayio_display_get_rotation(displayio_display_obj_t* self
 
 bool common_hal_displayio_display_refresh(displayio_display_obj_t* self, uint32_t target_ms_per_frame, uint32_t maximum_ms_per_real_frame) {
     if (!self->auto_refresh && !self->first_manual_refresh) {
-        uint64_t current_time = ticks_ms;
+        uint64_t current_time = supervisor_ticks_ms64();
         uint32_t current_ms_since_real_refresh = current_time - self->core.last_refresh;
         // Test to see if the real frame time is below our minimum.
         if (current_ms_since_real_refresh > maximum_ms_per_real_frame) {
@@ -327,7 +328,7 @@ bool common_hal_displayio_display_refresh(displayio_display_obj_t* self, uint32_
         }
         uint32_t remaining_time = target_ms_per_frame - (current_ms_since_real_refresh % target_ms_per_frame);
         // We're ahead of the game so wait until we align with the frame rate.
-        while (ticks_ms - self->last_refresh_call < remaining_time) {
+        while (supervisor_ticks_ms64() - self->last_refresh_call < remaining_time) {
             RUN_BACKGROUND_TASKS;
         }
     }
@@ -350,20 +351,20 @@ STATIC void _update_backlight(displayio_display_obj_t* self) {
     if (!self->auto_brightness || self->updating_backlight) {
         return;
     }
-    if (ticks_ms - self->last_backlight_refresh < 100) {
+    if (supervisor_ticks_ms64() - self->last_backlight_refresh < 100) {
         return;
     }
     // TODO(tannewt): Fade the backlight based on it's existing value and a target value. The target
     // should account for ambient light when possible.
     common_hal_displayio_display_set_brightness(self, 1.0);
 
-    self->last_backlight_refresh = ticks_ms;
+    self->last_backlight_refresh = supervisor_ticks_ms64();
 }
 
 void displayio_display_background(displayio_display_obj_t* self) {
     _update_backlight(self);
 
-    if (self->auto_refresh && (ticks_ms - self->core.last_refresh) > self->native_ms_per_frame) {
+    if (self->auto_refresh && (supervisor_ticks_ms64() - self->core.last_refresh) > self->native_ms_per_frame) {
         _refresh_display(self);
     }
 }
diff --git a/shared-module/displayio/EPaperDisplay.c b/shared-module/displayio/EPaperDisplay.c
index 252b39eb74..91d4bb7f9f 100644
--- a/shared-module/displayio/EPaperDisplay.c
+++ b/shared-module/displayio/EPaperDisplay.c
@@ -36,6 +36,7 @@
 #include "shared-bindings/time/__init__.h"
 #include "shared-module/displayio/__init__.h"
 #include "supervisor/shared/display.h"
+#include "supervisor/shared/tick.h"
 #include "supervisor/usb.h"
 
 #include <stdint.h>
@@ -176,7 +177,7 @@ uint32_t common_hal_displayio_epaperdisplay_get_time_to_refresh(displayio_epaper
         return 0;
     }
     // Refresh at seconds per frame rate.
-    uint32_t elapsed_time = ticks_ms - self->core.last_refresh;
+    uint32_t elapsed_time = supervisor_ticks_ms64() - self->core.last_refresh;
     if (elapsed_time > self->milliseconds_per_frame) {
         return 0;
     }
@@ -340,7 +341,7 @@ void displayio_epaperdisplay_background(displayio_epaperdisplay_obj_t* self) {
             bool busy = common_hal_digitalio_digitalinout_get_value(&self->busy);
             refresh_done = busy != self->busy_state;
         } else {
-            refresh_done = ticks_ms - self->core.last_refresh > self->refresh_time;
+            refresh_done = supervisor_ticks_ms64() - self->core.last_refresh > self->refresh_time;
         }
         if (refresh_done) {
             self->refreshing = false;
diff --git a/shared-module/displayio/display_core.c b/shared-module/displayio/display_core.c
index a73ea81d1f..658daa8d69 100644
--- a/shared-module/displayio/display_core.c
+++ b/shared-module/displayio/display_core.c
@@ -35,6 +35,7 @@
 #include "shared-bindings/time/__init__.h"
 #include "shared-module/displayio/__init__.h"
 #include "supervisor/shared/display.h"
+#include "supervisor/shared/tick.h"
 
 #include <stdint.h>
 #include <string.h>
@@ -281,7 +282,7 @@ void displayio_display_core_set_region_to_update(displayio_display_core_t* self,
 }
 
 void displayio_display_core_start_refresh(displayio_display_core_t* self) {
-    self->last_refresh = ticks_ms;
+    self->last_refresh = supervisor_ticks_ms64();
 }
 
 void displayio_display_core_finish_refresh(displayio_display_core_t* self) {
@@ -289,7 +290,7 @@ void displayio_display_core_finish_refresh(displayio_display_core_t* self) {
         displayio_group_finish_refresh(self->current_group);
     }
     self->full_refresh = false;
-    self->last_refresh = ticks_ms;
+    self->last_refresh = supervisor_ticks_ms64();
 }
 
 void release_display_core(displayio_display_core_t* self) {
diff --git a/shared-module/network/__init__.c b/shared-module/network/__init__.c
index 96648b260c..925e9a2a30 100644
--- a/shared-module/network/__init__.c
+++ b/shared-module/network/__init__.c
@@ -31,6 +31,8 @@
 #include "py/mphal.h"
 #include "py/mperrno.h"
 
+#include "supervisor/shared/tick.h"
+
 #include "shared-bindings/random/__init__.h"
 
 #include "shared-module/network/__init__.h"
@@ -53,7 +55,7 @@ void network_module_deinit(void) {
 
 void network_module_background(void) {
     static uint32_t next_tick = 0;
-    uint32_t this_tick = ticks_ms;
+    uint32_t this_tick = supervisor_ticks_ms32();
     if (this_tick < next_tick) return;
     next_tick = this_tick + 1000;
 
diff --git a/shared-module/usb_hid/Device.c b/shared-module/usb_hid/Device.c
index bed7d163f9..8744f2ed31 100644
--- a/shared-module/usb_hid/Device.c
+++ b/shared-module/usb_hid/Device.c
@@ -30,6 +30,7 @@
 #include "shared-bindings/usb_hid/Device.h"
 #include "shared-module/usb_hid/Device.h"
 #include "supervisor/shared/translate.h"
+#include "supervisor/shared/tick.h"
 #include "tusb.h"
 
 uint8_t common_hal_usb_hid_device_get_usage_page(usb_hid_device_obj_t *self) {
@@ -46,8 +47,8 @@ void common_hal_usb_hid_device_send_report(usb_hid_device_obj_t *self, uint8_t*
     }
 
     // Wait until interface is ready, timeout = 2 seconds
-    uint64_t end_ticks = ticks_ms + 2000;
-    while ( (ticks_ms < end_ticks) && !tud_hid_ready() ) {
+    uint64_t end_ticks = supervisor_ticks_ms64() + 2000;
+    while ( (supervisor_ticks_ms64() < end_ticks) && !tud_hid_ready() ) {
         RUN_BACKGROUND_TASKS;
     }
 
diff --git a/supervisor/shared/rgb_led_status.c b/supervisor/shared/rgb_led_status.c
index 940cbf1f27..f751a7ffd5 100644
--- a/supervisor/shared/rgb_led_status.c
+++ b/supervisor/shared/rgb_led_status.c
@@ -27,6 +27,7 @@
 #include "mphalport.h"
 #include "shared-bindings/microcontroller/Pin.h"
 #include "rgb_led_status.h"
+#include "supervisor/shared/tick.h"
 
 #ifdef MICROPY_HW_NEOPIXEL
 uint8_t rgb_status_brightness = 63;
@@ -360,7 +361,7 @@ void prep_rgb_status_animation(const pyexec_result_t* result,
                                rgb_status_animation_t* status) {
     #if defined(MICROPY_HW_NEOPIXEL) || (defined(MICROPY_HW_APA102_MOSI) && defined(MICROPY_HW_APA102_SCK)) || (defined(CP_RGB_STATUS_LED))
     new_status_color(ALL_DONE);
-    status->pattern_start = ticks_ms;
+    status->pattern_start = supervisor_ticks_ms32();
     status->safe_mode = safe_mode;
     status->found_main = found_main;
     status->total_exception_cycle = 0;
@@ -405,11 +406,11 @@ void prep_rgb_status_animation(const pyexec_result_t* result,
 
 void tick_rgb_status_animation(rgb_status_animation_t* status) {
     #if defined(MICROPY_HW_NEOPIXEL) || (defined(MICROPY_HW_APA102_MOSI) && defined(MICROPY_HW_APA102_SCK)) || (defined(CP_RGB_STATUS_LED))
-    uint32_t tick_diff = ticks_ms - status->pattern_start;
+    uint32_t tick_diff = supervisor_ticks_ms32() - status->pattern_start;
     if (status->ok) {
         // All is good. Ramp ALL_DONE up and down.
         if (tick_diff > ALL_GOOD_CYCLE_MS) {
-            status->pattern_start = ticks_ms;
+            status->pattern_start = supervisor_ticks_ms32();
             tick_diff = 0;
         }
 
@@ -424,7 +425,7 @@ void tick_rgb_status_animation(rgb_status_animation_t* status) {
         }
     } else {
         if (tick_diff > status->total_exception_cycle) {
-            status->pattern_start = ticks_ms;
+            status->pattern_start = supervisor_ticks_ms32();
             tick_diff = 0;
         }
         // First flash the file color.
diff --git a/supervisor/shared/safe_mode.c b/supervisor/shared/safe_mode.c
index d8d3ab379c..363181da06 100644
--- a/supervisor/shared/safe_mode.c
+++ b/supervisor/shared/safe_mode.c
@@ -34,6 +34,7 @@
 #include "supervisor/shared/rgb_led_colors.h"
 #include "supervisor/shared/rgb_led_status.h"
 #include "supervisor/shared/translate.h"
+#include "supervisor/shared/tick.h"
 
 #define SAFE_MODE_DATA_GUARD 0xad0000af
 #define SAFE_MODE_DATA_GUARD_MASK 0xff0000ff
@@ -59,14 +60,14 @@ safe_mode_t wait_for_safe_mode_reset(void) {
     common_hal_digitalio_digitalinout_construct(&status_led, MICROPY_HW_LED_STATUS);
     common_hal_digitalio_digitalinout_switch_to_output(&status_led, true, DRIVE_MODE_PUSH_PULL);
     #endif
-    uint64_t start_ticks = ticks_ms;
+    uint64_t start_ticks = supervisor_ticks_ms64();
     uint64_t diff = 0;
     while (diff < 700) {
         #ifdef MICROPY_HW_LED_STATUS
         // Blink on for 100, off for 100, on for 100, off for 100 and on for 200
         common_hal_digitalio_digitalinout_set_value(&status_led, diff > 100 && diff / 100 != 2 && diff / 100 != 4);
         #endif
-        diff = ticks_ms - start_ticks;
+        diff = supervisor_ticks_ms64() - start_ticks;
     }
     #ifdef MICROPY_HW_LED_STATUS
     common_hal_digitalio_digitalinout_deinit(&status_led);
diff --git a/supervisor/shared/tick.c b/supervisor/shared/tick.c
new file mode 100644
index 0000000000..69256081c4
--- /dev/null
+++ b/supervisor/shared/tick.c
@@ -0,0 +1,94 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Jeff Epler 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 "supervisor/shared/tick.h"
+#include "supervisor/filesystem.h"
+#include "supervisor/shared/autoreload.h"
+
+static volatile uint64_t ticks_ms;
+static volatile uint32_t background_ticks_ms32;
+
+#if CIRCUITPY_GAMEPAD
+#include "shared-module/gamepad/__init__.h"
+#endif
+
+#if CIRCUITPY_GAMEPADSHIFT
+#include "shared-module/gamepadshift/__init__.h"
+#endif
+
+#include "shared-bindings/microcontroller/__init__.h"
+
+void supervisor_tick(void) {
+
+    ticks_ms ++;
+
+#if CIRCUITPY_FILESYSTEM_FLUSH_INTERVAL_MS > 0
+    filesystem_tick();
+#endif
+#ifdef CIRCUITPY_AUTORELOAD_DELAY_MS
+    autoreload_tick();
+#endif
+#ifdef CIRCUITPY_GAMEPAD_TICKS
+    if (!(ticks_ms & CIRCUITPY_GAMEPAD_TICKS)) {
+        #if CIRCUITPY_GAMEPAD
+        gamepad_tick();
+        #endif
+        #if CIRCUITPY_GAMEPADSHIFT
+        gamepadshift_tick();
+        #endif
+    }
+#endif
+}
+
+uint64_t supervisor_ticks_ms64() {
+    uint64_t result;
+    common_hal_mcu_disable_interrupts();
+    result = ticks_ms;
+    common_hal_mcu_enable_interrupts();
+    return result;
+}
+
+uint32_t supervisor_ticks_ms32() {
+    return ticks_ms;
+}
+
+extern void run_background_tasks(void);
+
+void supervisor_run_background_tasks_if_tick() {
+    uint32_t now32 = ticks_ms;
+
+    if (now32 == background_ticks_ms32) {
+        return;
+    }
+    background_ticks_ms32 = now32;
+
+    run_background_tasks();
+}
+
+void supervisor_fake_tick() {
+    uint32_t now32 = ticks_ms;
+    background_ticks_ms32 = (now32 - 1);
+}
diff --git a/supervisor/shared/tick.h b/supervisor/shared/tick.h
new file mode 100644
index 0000000000..7ce8281ba9
--- /dev/null
+++ b/supervisor/shared/tick.h
@@ -0,0 +1,67 @@
+/*
+ * This file is part of the MicroPython project, http://micropython.org/
+ *
+ * The MIT License (MIT)
+ *
+ * Copyright (c) 2019 Jeff Epler 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 __INCLUDED_SUPERVISOR_TICK_H
+#define __INCLUDED_SUPERVISOR_TICK_H
+
+#include <stdint.h>
+
+/** @brief To be called once every ms
+ *
+ * The port must call supervisor_tick once per millisecond to perform regular tasks.
+ * This is called from the SysTick interrupt or similar, and is safe to call in an
+ * interrupt context.
+ */
+extern void supervisor_tick(void);
+/** @brief Cause background tasks to be called soon
+ *
+ * Normally, background tasks are only run once per tick.  For other cases where
+ * an event noticed from an interrupt context needs to be completed by a background
+ * task activity, the interrupt can call supervisor_fake_tick.
+ */
+extern void supervisor_fake_tick(void);
+/** @brief Get the lower 32 bits of the time in milliseconds
+ *
+ * This can be more efficient than supervisor_ticks_ms64, for sites where a wraparound
+ * of ~49.5 days is not harmful.
+ */
+extern uint32_t supervisor_ticks_ms32(void);
+/** @brief Get the full time in milliseconds
+ *
+ * Because common ARM mcus cannot atomically work with 64-bit quantities, this
+ * function must briefly disable interrupts in order to return the value.  If
+ * only relative durations of less than about ~49.5 days need to be considered,
+ * then it may be possible to use supervisor_ticks_ms64 instead.
+ */
+extern uint64_t supervisor_ticks_ms64(void);
+/** @brief Run background ticks, but only about every millisecond.
+ *
+ * Normally, this is not called directly.  Instead use the RUN_BACKGROUND_TASKS
+ * macro.
+ */
+extern void supervisor_run_background_if_tick(void);
+
+#endif
diff --git a/supervisor/supervisor.mk b/supervisor/supervisor.mk
index b2e4eb1dcf..5e997ee78e 100644
--- a/supervisor/supervisor.mk
+++ b/supervisor/supervisor.mk
@@ -10,6 +10,7 @@ SRC_SUPERVISOR = \
 	supervisor/shared/safe_mode.c \
 	supervisor/shared/stack.c \
 	supervisor/shared/status_leds.c \
+	supervisor/shared/tick.c \
 	supervisor/shared/translate.c
 
 ifndef $(NO_USB)