The Atmel I2C peripheral supports arbitrary I2C frequencies.
Since the `i2c_speed_t` enum just encodes the raw frequency values,
we can just use them in the peripheral definition.
We just have to remove the switch-case block that will generate an error
for values outside of `i2c_speed_t`.
Currently only samd21 used the 32 kHz clock for EXTI which makes it miss fast events.
All newer members of the family use the MAIN clock.
While touching this, also make the clock source configurable to this can be overwritten,
e.g. in the board config if desired.
If a write to a full tsrb is attempted with disabled interrupts
or in a interrupt then a deadlock will occure. To avoid this make
space in the ringbuffer by synchronously writing to uart.
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.
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.
For consistency, use named GCLKs.
- `SAM0_GCLK_32KHZ` will always be 2 for samd21
- `SAM0_GCLK_MAIN` will always be 0
So no change in functionality, just makes the code easier to understand.
bitarithm.h is not needed for the interface of shed but may cause conflicts
due to different definitions of SETBIT and CLRBIT
common implementations are: (value, offset) xor (value, mask) bitarithm
implements the later
frac.c and nrf52/usbdev.c use bitarithm.h but where missing the include
sam0/rtt.c defined a bit using mask from bitarithm,
changed that to the soulution used in sam0/rtc.c
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.
To simplify board definitions and for unification between samd2x and
newer models, don't use the GCLK bitmask in board definitions.
Instead use the GCLK index and generate the bitmask when needed.
The common ADC API dictates that a sample call must return -1 on an
incorrect resolution. The sam0 ADC implementation instead threw an
assertion failure.
Currently, spi_acquire() will always re-configure the SPI bus.
If the configuration did not change, this is entirely uneccecary
and makes SPI operations take longer than needed.
Instead, compare the current configuration with the new configuration
and skip the initialisation if it didn't change since the last call.
The RTC expects to be clocked from a 1kHz source.
Previously it would re-configure GCLK2 from 32kHz to 1kHz when used.
Since GCLK2 is also used by EIC, this would break external interrupts
in strange and unexpected ways.
Dedicate a 1kHz clock to it to avoid the damage.
From the data sheet:
> The COUNT register requires synchronization when reading.
> Disabling the synchronization will prevent reading valid
> values from the COUNT register.
Without this bit enabled, rtt_get_counter() will always return 0.
This change is for all boards with a sam0 cpu. This cpu just has one ADC.
It is unnecessary to have defines with ADC_0_ prefix as if multiple ADCs
are possible.
Some defines were not used, such as ADC_0_EN, ADC_0_CHANNELS,
ADC_MAX_CHANNELS, ADC_0_CLK_SOURCE, ADC_0_CHANNELS
Change all ADC_0_ prefixes to ADC_
In fractional mode, 3 bits are used to store the fractional part.
Therefore we must multiply / divide by 8 instead of 10 in order to
get the correct values.
A naive implementation may set a RTC alarm in 30s by calling
struct tm now;
rtc_get_time(&now);
now.tm_sec += 30;
rtc_set_alarm(&now, _cb, NULL);
This works for RTC implementations that use a RTT internally and call
mktime() to convert the struct tm to a unix timestamp, as mktime() will
normalize the struct in the process.
Call rtc_tm_normalize() when the RTC uses separate registers for time / date
components to ensure it is normalized.
This also modifies tests/periph_rtc to exercise this case.
The INTFLAGS register is cleared by writing a 1 to the corresponding interrupt
flag bit. From the samr21's manual:
> Writing a zero to this bit has no effect.
> Writing a one to this bit clears the Compare 0 interrupt flag.
This is a common pattern in flag registers.
This RTT driver is using or-equal to clear the flags, which means it can
possibly clear other interrupts. There's a small chance that one event is
missed if it happens very close to another event.
Credits to @benpicco, @dylad for pointing out missing fixes.
_exti() always assumes only 2 ports, so it will always fail when using
e.g. port C or port D on same54.
Instead, determine the number of ports from the dimensions of the exti_config
array.
This adds supoprt for the Atmel SAMD51 & SAME54 SoC.
The SAME5x/SAMD5x is a line of Cortex-M4F MCUs that share peripherals
with the samd2x Cortex-M0+ and saml1x Cortex-M23 parts.
This cleans up the sam0 timer driver:
- remove the check for the unused freq parameter
- the MCU provides dedicated SET/CLR registers to avoid
read-modify-write, so don't do read-modify-write on them.
- workaround a possible hardware bug on SAMD5x:
loop until the CMD_READSYNC is really set
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.
