stm32f1 periph_rtc implementation gets a 1s resolution by dividing
CLOCK_LSx by 32768. This only make sense if CLOCK_LSE is set,
otherwise CLOCK_LSI=~40000, which will lead to an imprecise rtc.
lpc23xx has 3 sleep modes and one idle mode.
`PM_NUM_MODES` must only count the idle modes.
In practise, this makes no difference since `mode 3` (IDLE) is
the `default` case in `pm_set()` anyway.
The calculation of `_state_index` is broken for `port = 2`
_gpio_isr_map[n + (port<<1)];
Will not yield the right result. As a consequence, IRQs on Port 2
are not working.
The right thing here would be
_gpio_isr_map[n + (port ? 32 : 0)];
But we might just re-using the `_isr_map_entry()` function.
Also only iterate as many times as there are set interrupt bits.
The ARM CortexM vector table has some reserved fields which are used by
some manufacturers to store their custom image information. In
particular, NXP QN908X stores the checksum, Code Read Protection, image
type and boot block pointer in this region.
This patch allows the cpu and board modules to define the value of these
fields at build time by defining a macro.
GCLK_ID and APBCMASK entries are not always uniform.
The previous hack would already break for TCC3.
Just explosively write down the cases, there are only 5 at most.
The CPU has 4 hardware timers.
Configuration for all 4 timers exists, but the compile-time range
check has an off-by-one error, causing the last timer to remain
inaccessible.
This commit enables Cortex-M CPU interrupt sub-priorities
and allows the PendSV interrupt to have a priority different
from the default one. Together these two preprocessor
defines can be used to have PendSV always run as the last interrupt
before returning from the interrupt stack back to the user space.
Running PendSV as the last interrupt before returning to the
user space is recommended by ARM, as it increases efficiency.
Furthermore, that change enhances stability a lot with the
new nRF52 SoftDevice support, currently being worked in
PR #9473.
This commit merely enables sub-priorities and a separate
PendSV priority to be used without changing the default
RIOT behaviour.
The DFLL on samd5x has a hardware bug that requires a special
re-enabling sequence when it is disabled and then re-enabled again.
When running the clock on-demand, the hardware handles the disabling
and re-enabling so that sequence does not get executed.
To reproduce, run `tests/periph_uart` on `same54-xpro`.
Without this patch the test will get seemingly stuck on `sleep_test()`.
(In fact it keeps running, but the DFLL has the wrong frequency so the
UART baudrate is wrong).
In this test, on `same54-xpro` only UART0 is sourced from DFLL.
So if the UART is disabled the DFLL will be turned off as well.
Switch from the on-chip LDO to the on-chip buck voltage regulator
when not fast internal oscillators are used.
On `saml21-xpro` with `examples/default` this gives
**before:** 750 µA
** after:** 385 µA
