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.
- 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()
The currently supported SAM0 MCUs (samd21, saml21, saml1x) share the same
Timer peripheral, yet each of them carries it's own copy of the Timer
driver.
This introduces a new timer driver that is common for all sam0 MCUs and
uses structs for configuration instead of defines.
The currently supported SAM0 MCUs (samd21, saml21, saml1x) share the
same RTC peripheral, yet each of them carries it's own copy of the RTT
driver.
Unify the drivers and move them to sam0_common.
The currently supported SAM0 MCUs (samd21, saml21, saml1x) share the
same RTC peripheral, yet each of them carries it's own copy of the RTC
driver.
Unify the drivers and move them to sam0_common.
The INTENSET, INTENCLR, INTFLAG registers are write-1-to-confirm
registers, so writing zeroes will not affect anything, on the other
hand, a compiler generated read-modify-write cycle may unintentionally
affect more bits than the one being set. Avoid by using direct
assignment instead of or-assignment (|=) or bitfield writes (.bit.xxx=).
