Fix typo in unknown_1 register access

[Gadgetoid]

This would have silently created a property on the class instance, rather than writing the register.

In a nutshell, this is why using properties in this way - while super tidy - is a bad idea. It's extremely easy to mistype a property name, and since Python will happily create this property instead of throwing an AttributeError you'll be none the wiser.

There must be a way to lint for this- but I couldn't find anything more graceful than __slots__ which is tediously verbose and may have unintended side-effects.

[siddacious]

@Gadgetoid I've definitely been bitten by the issue you mentioned with properties so I'm all for coming up with a more robust solution. Having a linter or other automated check catch them would be nice but I'm open to other suggestions as well. Feel free to open an issue on https://github.com/adafruit/Adafruit_CircuitPython_Register with any ideas.

I'm rather fond of the Register library but I'll be the first to admit that it's due for a re-think

[Gadgetoid]

Ha! And I'm rather fond of my i2c-device library, but I'd also be first in line to criticise it.

My favourite possible solution to this problem is generative i2c bindings, using a device descriptor to auto-generate the code. As much as this idea tickles me I can immediately see all the ongoing maintenance issues with it (people changing the generated code instead of the course, and so on).

I love how clean the Register library is versus the huge glob of runtime definition I use in i2c-device, see this horror:

https://github.com/pimoroni/bme280-python/blob/a2da3f1c12b0c12bc630fc1b31021f06f3c29a1d/library/bme280/__init__.py#L123-L206

i2c-device does some chilling things under the hood to make this work and is also subject to typos, failing with cryptic errors. Masking out multiple fields in multi-byte registers is also particularly onerous. Doing this in lieu of a struct.unpack is... yeah:

https://github.com/pimoroni/bme280-python/blob/a2da3f1c12b0c12bc630fc1b31021f06f3c29a1d/library/bme280/__init__.py#L184-L205

But I'm keen to be able to express an i2c device in a declarative manner and not have to fiddle with bit shifting or conversion more than once.

With Register I guess you can overload __setattr__ to refuse to set attributes that aren't already in __dict__.