[Microbit-Python] Driving Neopixels with Pxx other than P0, P1, P2?

[Nevil Hunt]

Hi Carlos,


I've had a look at the signal on a scope and there is no sign of movement on P8, etc so I don't think it is just a pull up issue. In fact I think the NeoPixel protocol drives the signals both high and low, unlike I2C which relies on the pullups to pull the signal high.


Interestingly looking through your microbit broadcast I notice 4tronix are using NeoPixels on P13 and have a bit of Python and PXT showing how to do it. I wonder if they have actually tried it with Python, or just with PXT.


Interestingly I then tried it with PXT and with the new version of PXT I can't get it to enable the NeoPixel Library so I've dropped Tom & Peli an email.


Cheers,


Nevil


________________________________
From: Microbit <microbit-bounces+nevil.hunt=hotmail.co.uk at python.org> on behalf of Carlos Pereira Atencio <carlosperate at gmail.com>
Sent: 13 December 2016 11:32
To: For Pythonic MicroBit related discussions
Subject: Re: [Microbit-Python] Driving Neopixels with Pxx other than P0, P1, P2?

A bit of shot in the dark, since I haven't really manually driven neopixels before, but if they run on the 1-wire protocol, don't the need a pull up? The large GPIO connectors would have a weak pull up on then, so that could be the main difference.


On 13 December 2016 at 09:40, Nevil Hunt <nevil.hunt at hotmail.co.uk<mailto:nevil.hunt at hotmail.co.uk>> wrote:

Hi Damien,


Thanks for the suggestion. I gave it a go but unfortunately it didn't bring it to life.

I tried P8,12,13,14,15,16 and none of them drive the NeoPixels.

If enabling NeoPixels on these additional Pxx pins would just be a simple s/w change it would be good to have as the P0,P1,P2 are precious resources.

Either way this is the first time I've had a play with NeoPixels and they are good fun!


Cheers,


Nevil


________________________________
From: Microbit <microbit-bounces+nevil.hunt=hotmail.co.uk at python.org<mailto:hotmail.co.uk at python.org>> on behalf of Damien George <damien.p.george at gmail.com<mailto:damien.p.george at gmail.com>>
Sent: 13 December 2016 02:22
To: For Pythonic MicroBit related discussions
Subject: Re: [Microbit-Python] Driving Neopixels with Pxx other than P0, P1, P2?

Hi Nevil,

Neopixels should work on all pins.... make sure the pin is not being
used for something else (eg display), then try doing write_digital on
that pin before using it as a neopixel output.

Cheers,
Damien.

On 13 December 2016 at 06:32, Nevil Hunt <nevil.hunt at hotmail.co.uk<mailto:nevil.hunt at hotmail.co.uk>> wrote:
> Hi,
>
>
> I've just got the micro:bit driving the Adafruit Neopixel Feather board
> using the example Python code in the 'read-the-docs' and it works well! (but
> I might need to buy a new pair of sunglasses!)
>
>
> The 'read-the-docs' says it can use P0, P1 or P2 which I've checked all
> work. I then wondered if it would work with other Pxx such as P8, P12 or P16
> but it doesn't.
>
>
> Since driving Neopixels is entirely digital is there any fundamental reason
> why the use of other Pxx couldn't one day be enabled?
>
>
>
> Cheers,
>
>
> Nevil
>
>
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