[Microbit-Python] Slowness as integers move beyond 256

[Mark Shannon]

Hi,

We actually use an exponential scale of pwm duty-cycles, rather than bcm:
https://github.com/bbcmicrobit/micropython/blob/master/source/microbit/microbitdisplay.cpp#L193

The shortest of which is only 35 microseconds. You'll need a fast camera :)

The complete cycle to illuminate all the LEDs takes 18 millseconds.
If you could film at some multiple of that rate, then apply a low-pass
filter afterwards, you might get the correct visual effect.
I doubt it is worth the effort.

Cheers,
Mark.

On 06/01/16 18:38, David Whale wrote:
> The micro:bit uses BCM for the on screen LEDS (Binary Coded Modulation),
> and the update rate is such that it interferes quite badly with POV
> (persistence of vision) style implementations. I was chatting to Joe
> Finney at Lancaster about this and we came to the conclusion it's not
> worth 'going there', as the update rate of the display would need
> changing, and this would affect a range of other timing events.
>
> David.
>
> ___________________________________________________________
> David Whale, B.Sc (Hons), MIET
> *Software Engineer and IET Schools Liaison Officer, Essex*
>
> email: dwhale at theiet.org <mailto:dwhale at theiet.org>
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> On 6 January 2016 at 14:04, M.-A. Lemburg <mal at egenix.com
> <mailto:mal at egenix.com>> wrote:
>
>     I've fixed the logic for calculating the argument for math.sin()
>     to always be in the range of 0..2*pi. This makes the slowness
>     go away.
>
>     BTW: I tried to film the waves display, but found that the LEDs
>     appear to be using pulse-width modulation (PWM) to output different
>     brightness levels. As a result the film doesn't show the nice
>     modulation,
>     but instead a more or less erratic blinking.
>
>     Cheers,
>     --
>     Marc-Andre Lemburg
>     eGenix.com
>
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