- The `periph_flashpage` driver expects the manual write bit to be set
This should be set by default, but the SAM D20/SAM D21 errata sheets
correct that this is indeed *not* set by default, which may cause
spurious writes.
- SAM D20 may not wake up from any sleep mode if sleep power reduction
is enabled for the NVM block.
It turns out hooking up an unused peripheral to a disabled GCLK
leads to surprising power savings.
Name the GCLK to be more explicit (and since not all members of
the extended samd2x family have a GCLK7).
Turns out we can just use a non-existing GCLK ID for this, this
even saves us a real GCLK that we can use for something else.
Also make sure to disable *all* peripherals by using
`GCLK_CLKCTRL_ID_Msk` instead of relying on a magic value.
Looks like we previously missed some, since this leads to some
additional power savings:
master: 4.22 mA
this patch: 4.09 mA
The split between GEN2_ULP32K and GEN3_ULP32K was introduced to fix
a failure in tests/periph_wdt when the external oscillator was used.
By not running the external oscillator on demand, the failure can no
longer be observed, so default GEN3_ULP32K to GEN2_ULP32K.
Instead of hard-coding the peripheral clocks to CLOCK_CORECLOCK
introduce helper functions to return the frequency of the individual
GCLKs and use those for baud-rate calculations.
This requires the GCLK to be part of the peripheral's config struct.
While this is already the case for most peripherals, this also adds
it for those where it wasn't used before.
As it defaults to 0 (CLOCK_CORECLOCK) no change is to be expected.
- Removed stdio_init() from newlib's _init(), as this is too late in the boot
process to allow DEBUG()ing during periph_init()
- Added stdio_init() to the various cpu_init() routines of the ARM CPUs just
before periph_init()
