The UART TX and TX lines on SAMD5x and SAML1x can be inverted.
However, the flags don't do exactly what one would expect.
See errata 2.18.5: SERCOM-UART: TXINV and RXINV Bits Reference:
> The TXINV and RXINV bits in the CTRLA register have inverted functionality.
>
> Workaround:
> In software interpret the TXINV bit as a functionality of RXINV, and conversely,
> interpret the RXINV bit as a functionality of TXINV.
This adds the feature `periph_wdt_warning_period` that indicates that a
platform WDT driver implementation supports a configurable
CONFIG_WDT_WARNING_PERIOD.
When the SPI peripheral is disabled, the output lines will become HIGH-Z.
If the clk pin is not pulled HIGH or LOW, connected SPI slaves will start drawing current expectedly.
Writing a 1 bit clears the interrupt flag, writing with |= is thus
uneccecary (and actually an error as this would clear *all* flags).
This cleanup was already done for rtt.c, but rtc.c missed out.
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.
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.)
This moves the following modules to a architecture-specific Makefile.dep
file:
- cortexm_common
- cortexm_common_periph
- newlib
- newlib_nano
- periph
Add a fucntion to switch between LDO and Buck concerter to provide the
internal CPU voltage.
The Buck Converter is not compatible with internal fast oscillators (DFLL, DPLL)
and requires an inductivity to be present on the board.
The ROM size is encoded in the part number of the Atmel SAM chips.
RAM size is not encoded directly, so get it by parsing the chip's vendor file.
The file remains in the page cache for the compiler to use, so the overhead
should be minimal:
on master:
Benchmark #1: make BOARD=samr21-xpro -j
Time (mean ± σ): 527.9 ms ± 4.9 ms [User: 503.1 ms, System: 69.6 ms]
Range (min … max): 519.7 ms … 537.2 ms 10 runs
with this patch:
Benchmark #1: make BOARD=samr21-xpro -j
Time (mean ± σ): 535.6 ms ± 4.0 ms [User: 507.6 ms, System: 75.1 ms]
Range (min … max): 530.6 ms … 542.0 ms 10 runs
All the more recent vendor files have them, so include them for samr30 too.
It is expected for this to become obsolete with the next vendor file update.
