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GPIO for limit switches?  

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-Matt-
(@matt-26)
Member
GPIO for limit switches?

I've read a few comments where users complain about the homing system (which relies on stall detection).

It has made me wonder about the capabilities of the GPIO board. Would the inputs be fast enough to support hardware limit or homing switches as a potential mod or upgrade?

Posted : 05/08/2025 9:02 am
-Matt-
(@matt-26)
Member
Topic starter answered:
RE:

I found the Prusa open source page on the GPIO board...

https://help.prusa3d.com/article/gpio-module_734695

The IC on the GPIO board seems fairly promising, it apparently has 100kHz (standard mode) and 400kHz (fast mode) and supports inturrupts on the inputs.

TI Datasheet for TCA6408A

However, one of the comments on the Prusa open source page led me to an older version of that page with a bit more info on the inputs...

https://help.prusa3d.com/article/gpio-module_73469 5" target="_blank" rel="noopener"> https://web.archive.org/web/20250115150956/https://help.prusa3d.com/article/gpio-module_734695

Unfortunately this suggests that the GPIO inputs are only polled every half second, which may not be fast enough for limit or homing switches.

It seems like using the GPIO board for limit or homing switches could potentially be viable, but it would probably need a custom firmware from Prusa to work well.

Posted : 05/08/2025 11:16 am
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