Some SAMD21 CPUs from the D series have an additional TCC3 and / or
an additional analog comperator.
Add those to `vectors.c`.
Also rename the i2s interrupt to the proper name used by other sam0
devices.
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 sam0 MCUs all have a DAC peripheral.
The DAC has a resulution of 10 or 12 bits and can have one or two
output channels.
The output pins are always hard-wired to PA2 for DAC0 and PA5 for DAC1
if it exists.
On the same54-xpro I would only get a max value of ~1V when using the
internal reference, so I configured it to use an external voltage reference.
The external reference pin is hard-wired to PA3, so you'll have to connect
that to 3.3V to get results.
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.
Also adapt the defines to the documentation
- CPUs define up to 4 power modes (from zero, the lowest power mode,
to PM_NUM_MODES-1, the highest)
- >> there is an implicit extra idle mode (which has the number PM_NUM_MODES) <<
Previously on saml21 this would always generate pm_set(3) which is an illegal state.
Now pm_layered will correctly generate pm_set(2) for IDLE modes.
Idle power consumption dropped from 750µA to 368µA and wake-up from standby is also
possible. (Before it would just enter STANDBY again as the mode register was never
written with the illegal value.)
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.
Creating an `exti_config` array for a new MCU manually is tedious and error prone.
Luckiely all information is already availiable in the vendor files.
Credit for this discovery & method goes to @Sizurka
The file was generated with
```C
int main(void) {
puts("static const int8_t exti_config[PORT_GROUPS][32] = {");
for (unsigned port = 1; port < 5; ++port) {
printf("#if PORT_GROUPS >= %d\n{\n", port);
for (unsigned pin = 0; pin < 32; ++pin) {
printf("#ifdef PIN_P%c%02uA_EIC_EXTINT_NUM\n", '@' + port, pin);
printf(" PIN_P%c%02uA_EIC_EXTINT_NUM,\n", '@' + port, pin);
printf("#else\n -1,\n#endif\n");
}
printf("},\n#endif\n\n");
}
puts("};");
return 0;
}
```
No changes in generated code are expected, but this makes adding new members
of the sam0 CPU families much easier.
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.
