Some terminology issues are fixed. (The speed of an UART interface is
the symbol rate. The unit it is measured in is baud, which is symbols
per second. There is no such thing as baudrate or even baud/s.)
The return codes are changed to use negative errno constants on error
to match the driver design rules. For backward compatibility, the
enum was updated to match the error codes. Unless an application
depends on the exact numerical value (which would be insane), this is
not breaking any code.
RTC on RTT usually runs at a frequency greater than 1 Hz, so sub-second
precision is available.
Add a function to get the current RTC timestamp together with it's sub-second
component.
The Silicon Labs Si705x sensors (Si7050/1/3/4/5) are very similar to the
Si7021 sensors featuring only a temperature sensor and no humidity
sensor. The only difference between the Si705x is the temperature
accuracy of the reading, ranging from +/- 0.1 C in the Si7051 to +/- 1 C
in the Si7050.
This patch adds support for this family of sensors extending the
functionality of the existing si70xx driver. Following the style of
other modules, this implements a pseudomodule per supported chip, adding
si7050, si7051, si7053, si7054 and si7055 pseudomodules.
As a minor change this patch also implements the missing
si70xx_get_serial, si70xx_get_id and si70xx_get_revision functions that
were declared in the si70xx.h header but implemented as private
functions. The si70xx_get_id() may be relevant for the application to
know at run time exactly which version of the hardware is installed.
The updated test running with a Si7051 shows the following output, which
seems consistent with the room temperature conditions during the test.
```
make SI70XX_VARIANT=si7051 -C tests/driver_si70xx/ all flash
```
```
SI70XX temperature and humidity sensor test application
Initializing sensor...
[OK]
Found SI7051 sensor, revision 32
temperature: 24.71 C
temperature: 24.69 C
```
tests/driver_ds3231
drivers/ds3231: add alarm support with IRQ
drivers/ds3231: alarm support and documentation
drivers/ds3231: alarm interrupt with mutex
drivers/ds3231: alarm, _unlock function
fixup! drivers/ds3231: add alarm support
