[Microbit-Python] Units for API functions.

[Nicholas H.Tollervey]

WRT the compass... I believe the underlying hardware isn't that great
when it comes accuracy.

N.

On 29/09/15 23:26, Mark Shannon wrote:
> 
> 
> On 29/09/15 15:11, Damien George wrote:
>> Hi Mark,
>>
>> I think brightness should range from 0-9 inclusive.  Reason: that's 10
>> values, it's Pythonic (range(10)), and most importantly you can encode
>> an image in a string using single digits: "09990\n09090\n...".
>>
>> The compass outputs a heading in degrees.
> Really? Mine must need fixing :(
> What about the x,y,z values?
> 
>>
>> The accelerometer is (or should be) in milli-g's.  Ie 1000=9.8m/s^2.
>>
>> I think that arguments which correspond to continuous numeric values
>> should allow int or float (with implicit truncation of float to int),
>> while others should be int only.  Eg set_pixel(x,y) should have x,y
>> int only, yet write_analog(v) should allow v to be a float.
>>
>> Cheers,
>> Damien.
>>
>>
>> On Tue, Sep 29, 2015 at 10:56 PM, Mark Shannon <mark at hotpy.org> wrote:
>>> Hi all,
>>>
>>> We've all had fun discussing the names of functions in the API,
>>> but what about units?
>>>
>>> So far, we have agreed on units for I/O pins and times.
>>>
>>> For pin I/O we accept values in the range 0 to 1023, with a unit of
>>> 3.3/1023
>>> volts.
>>> 0 to 1023 translates directly to the capability of the DAC/ADC on the
>>> device.
>>>
>>> For measuring time, it seems that milliseconds are the standard.
>>>
>>> That leaves brightness, the accelerometer and the compass.
>>>
>>> For brightness, I would like to propose using a linear scale of
>>> *perceived*
>>> brightness. Acceptable values would range from 0 to N, where N is in the
>>> range 10 to ~15.
>>> 0 is off. 1 to N are linearly increasing levels of brightness.
>>> The value passed to the underlying C++ layer must be in the range 0
>>> to 255.
>>> Therefore, a brightness of n would translate to roughly K**(n-1), where
>>> K**(N-1) would be about 255.
>>> Candidates for N are:
>>> 10, 10 is a natural limit for kids used to decimal.
>>> 11, it goes to 11 :)
>>> 15, 15 is the maximum hex digit and about the limit of being able to
>>> distinguish between brightness levels.
>>> (I prefer 11, the bbc iplayer volume goes to 11).
>>>
>>> What about ranges/units for the accelerometer or compass?
>>> Does anyone have any thoughts on those?
>>> If they are to be arbitrary, it might make sense to choose 0-1023 for
>>> consistency with the other I/O.
>>>
>>> In terms of the implementation, I would expect that all inputs take
>>> ints or
>>> floats and all outputs return ints. They should be documented as
>>> "number"
>>> throughout.
>>> E.g. Pin.write_analog(x) will take an int or float and be documented as
>>> taking any number between 0 and 1023.
>>>
>>> Cheers,
>>> Mark.
>>>
>>> P.S.
>>> If you haven't played with brightnesses, then try the attached program.
>>>
>>>
>>>
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>>>
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