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[Bug]: Using BSS138 based level shifters #234

@specialcircumstances

Description

@specialcircumstances

Description of the bug

So, this isn't really a bug, but perhaps someone will find this and it will help them solve this issue. Perhaps it could be added to the FAQ / Documentation for this very useful plugin :)

When using a level shifter based on BSS138 MOSFET types things won't work properly as they cannot support the frequencies properly.

In my case the issue was some colour issue, but especially the first LED (of an 8 pixel GRBW Neopixel strip) was always green.

The units in question are common and often provide 4 channels of bidirectional level conversion, for example:

https://www.adafruit.com/product/757
or
https://cdn.sparkfun.com/datasheets/BreakoutBoards/BSS138.pdf

Anyway, don't use them for this project, use 74AHCT125 instead.

Steps to reproduce

Use a BSS138 MOSFET type and you'll hit issues.

What happened instead?

Poor and incorrect pixel colours and activation.

Plugin version

any

OctoPrint version

any

(if relevant) OctoPi version

No response

Log Files & Screenshots

Image Image Image

Anything else?

You can close this, unless you want to keep it open until the FAQ is updated?

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