Don't use a state machine in AK8963: the start_measurements() method
should be called only once. Even if there's a magnetic sensor overflow
the only thing we should do is to discard the new data.
This also moves the _collect_samples() method to be inside _update()
since it's the only place it should be called from, the one running on
the timer thread.
We need to check the AK8963's id before anything else Here we are
reordering the calls to _calibrate() and _check_id(). After that we
don't need to read and write again the AK8963_CNTL1 register.
While at it do some renames as well:
- _configure() -> _setup_mode(): since now there's a
_bus->configure() it became confusing what actually it's
doing.
- make error messages say what we were actually trying to do but
couldn't. Also remove PSTR since this is linux-only.
- start_conversion() -> start_measurements(): We are instructing the
bus to start to get the samples, not to tell the chip to start an
analog->digital conversion like in other sensors.
Similar code was added in the read_raw() implementation for each bus.
Add a new POD struct read_raw to contain the registers from the AK8963
and use it instead as argument.
Lucas De Marchi
Staroselskii Georgii
Julien BERAUD
Andrew Tridgell
Víctor Mayoral Vilches