Add calibration offsets and radii as properties on BNO055 library

[katlings]

Issue #21

the @property decorator + Struct had some interesting __get__ interactions, resulting in some repetition in the code. Happy to revisit if someone has a better idea.

I didn't use the ReadOnlyStructs already defined in this file because letting the user overwrite the calibration is supported in Arduino, so someday it would be nice to do that here too. I don't think it'll take much

[caternuson]

Thanks for the PR. It's not passing the Travis check. Looks like it's missing docstrings. Let us know if you need help checking and reading the Travis report.

[tannewt]

@caternuson Would you mind picking this up? I think @katlings is travelling. They did this during the PyCascades sprint last week.

[katlings]

My bad! @tannewt is right, I'm on the road, but I should be able to find time to fix this up on Monday. If you'd like it sooner, feel free to take over!

[caternuson]

@katlings @tannewt I'm fine with waiting until Monday. I wouldn't be able to get to this myself until then anyway.

[katlings]

@caternuson Check again! :)

[deshipu]

It looks good and is readable, but that's a lot of repeated code. I wonder if it would make sense to have something like a context manager for encapsulating that code. Something like:

class Mode:
    __init__(self, sensor, mode):
        self.sensor = sensor
        self.mode = mode
        self.last_mode = None
   
    ___enter__(self):
        self.last_mode = self.sensor.mode
        self.sensor.mode = mode
        return self
      
    __exit__(self, exc_type, exc_value, traceback):
        self.sensor.mode = last_mode

and then:

with EnsureMode(self, CONFIG_MODE):
    return self._offsets_accelerometer

Alternatively (and I think ultimately better), perhaps we could have a mode-aware version of the Struct class? Something like:

class ModeStruct(Struct):
    def __init__(self, register_address, struct_format, mode):
        super().__init__(register_address, struct_format)
        self.mode = mode

    def __get__(self, obj, objtype=None):
        last_mode = obj.mode
        obj.mode = self.mode
        result = super().__get__(obj, objtype)
        obj.mode = last_mode
        return result

    def __set__(self, obj, value):
        last_mode = obj.mode
        obj.mode = self.mode
        super().__set__(obj, value)
        obj.mode = last_mode

[tannewt]

@deshipu That's a good idea but let's not require it for this PR. That way someone else can pick it up.

[katlings]

@deshipu I like both solutions; the mode struct in particular looks like it would enable manually setting these parameters (which I believe is supported) with no further fuss.

I'm still traveling and am happy to follow up when I get home tomorrow, though I don't have the right board to test this with and might need @tannewt's help for that.

[tannewt]

@katlings I'm happy to get you boards if you want to keep working on this when you get home.

[caternuson]

@katlings Thanks, this is looking good. Nice continued use of adafruit_register. Would you be up for adding write capability as well?

Current code for reading tests and works:

Adafruit CircuitPython 3.1.2 on 2019-01-07; Adafruit ItsyBitsy M0 Express with samd21g18
>>> import board, busio
>>> import adafruit_bno055
>>> i2c = busio.I2C(board.SCL, board.SDA)
>>> bno = adafruit_bno055.BNO055(i2c)
>>> bno.offsets_magnetometer
(0, 0, 0)
>>> bno.offsets_gyroscope
(-2, -2, 0)
>>> bno.offsets_accelerometer
(0, 0, 0)
>>> bno.radius_magnetometer
0
>>> 

[tannewt]

@katlings Still interested in wrapping this up?

[sjirwin]

The code is working from a python point of view, but the board does not always accept the new calibration value

>>> import board, busio
>>> import adafruit_bno055
>>> i2c = busio.I2C(board.SCL, board.SDA)
>>> sensor = adafruit_bno055.BNO055(i2c)
>>> sensor.radius_accelerometer, sensor.radius_magnetometer
((1000,), (0,))
>>> sensor.radius_accelerometer = 999,
>>> sensor.radius_accelerometer, sensor.radius_magnetometer
((1000,), (0,))
>>> sensor.radius_accelerometer = 999,
>>> sensor.radius_accelerometer, sensor.radius_magnetometer
((999,), (0,))
>>> sensor.radius_accelerometer, sensor.radius_magnetometer
((1000,), (0,))
>>> sensor.radius_accelerometer, sensor.radius_magnetometer
((1000,), (43,))

[tannewt]

This ready to go?

[caternuson]

Are 1D tuples the only way to get this to work? I'm concerned that subtle little , that's required when dealing with 1D tuples could end up being a source of confusion.

[sjirwin]

I am pretty sure we can make that more natural. Will look at it this weekend and submit an updated PR.

Any advice on how to submit the PR directly and avoid @katlings having to broker this through her fork?

[tannewt]

@sjirwin you can make a new PR to this repo and we can close this one.

[evaherrada]

Seems this PR was left open by mistake.