Jeff Epler 7f744a2369 Supervisor: move most of systick to the supervisor
This code is shared by most parts, except where not all the #ifdefs
inside the tick function were present in all ports.  This mostly would
have broken gamepad tick support on non-samd ports.

The "ms32" and "ms64" variants of the tick functions are introduced
because there is no 64-bit atomic read.  Disabling interrupts avoids
a low probability bug where milliseconds could be off by ~49.5 days
once every ~49.5 days (2^32 ms).

Avoiding disabling interrupts when only the low 32 bits are needed is a minor
optimization.

Testing performed: on metro m4 express, USB still works and
time.monotonic_ns() still counts up
2019-11-18 11:01:23 -06:00
..
2019-07-11 13:41:10 -04:00
2019-06-28 16:34:27 -04:00
2019-06-28 16:34:27 -04:00
2019-07-23 13:48:59 -04:00

CircuitPython Port To The ST Microelectronics STM32F4 Series

This is a port of CircuitPython to the STM32F4 series of chips.