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Partial debounce failure on keyboard keys

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e100:
Several of the keys on my computer keyboard sometimes generate 2 key press events when pressed once.
Does anyone know how modern keyboards do their debouncing?
I assumed it would all be done inside the keyboard controller chip and therefore I don't understand why only some keys are affected and not all keys.

RoGeorge:
Yes, all debouncing and key codes generating are done on the keyboard side, not on the PC.

Try opening the keyboard and clean it, maybe some liquid was spilled.  Depending on the model, some keyboards have sheets of membrane contacts that can be peeled apart for cleaning.

Bryn:
I had a similar problem with my tablet keyboard, only that it affected the space bar only and most times when I press that it would do several key press events at the one time (even down to the space bar being stuck as a result). I simply threw it out though...

Should also say that the "i" key on my laptop keyboard would sometimes trigger two press events at once but strangely was during the early days I had this laptop and since then had used an external keyboard from my old computer - and still going strong 14 years since I first got it.

SiliconWizard:
So yes, the debouncing is done in the keyboard's firmware.

If you suddenly get multiple key presses for one press, it basically means that the corresponding keys are bouncing for a longer time / slower than normal, which makes the integrated debouncing ineffective.

Reason is likely that the keys are either sticky (from accumulated dirt, liquid, etc) or just plain worn out - which would require a replacement.

You'll have to figure out if this is a membrane keyboard or a "mechanical" one. If this is a membrane keyboard and some basic cleaning doesn't help, unfortunately there's nothing much you'll be able to do except replacing the membrane (if you can even find a replacement.) Probably not worth the trouble compared to buying a new keyboard.

thm_w:
What is the model number of the keyboard?
While debouncing is done in the kb as mentioned above, very high polling rates might make key bounce worse. So if it is a high end keyboard, maybe some small chance you could try adjusting that before cleaning it.

https://www.clickspeedtester.com/keyboard-latency-test/

mx red key switches (linear) seem to be worse than a blue or brown (tactile) for this.

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