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geekhack Community => Keyboards => Topic started by: unicomp on Fri, 15 October 2010, 08:55:54

Title: How does a keyboard actually work?
Post by: unicomp on Fri, 15 October 2010, 08:55:54

I am quite interested in having a reasonable understanding of what goes on at the level of the electronics between the actuation of a key and the data being sent to the computer. Can anyone help me here? The reason that I am not just looking on some technical specification is because I don't want specific details, I just want to understand how the process works.

I know that the switches must complete a circuit, however it doesn't seem like every key would be wired to a controller that would then parse this in some individual way. Is this the notion of scanning?

Edit: I am also not particularly bothered about the explanation of the mechanics of the different switches, only that they all act as switches in that they complete circuits.

Title: How does a keyboard actually work?
Post by: keyboardlover on Fri, 15 October 2010, 10:05:24

Freakin keyboards, how do they work??

(http://www.littlelostrobot.com/images/slobot_guy.jpg)

Title: How does a keyboard actually work?
Post by: Findecanor on Fri, 15 October 2010, 10:16:40

This page explains it in more detail, with pictures: Keyboard Matrix Help (http://www.dribin.org/dave/keyboard/one_html/). It also explains how ghosting can be avoided using diodes.

Most keyboards, though, have anti-ghosting done in the controller. It simply detects situations where there could potentially be phantom key presses and then prevents new key presses to be sent to the host computer until keys have been released.

Title: How does a keyboard actually work?
Post by: Rajagra on Sat, 16 October 2010, 03:10:13

Quote from: ripster;234206

Transistors are easier to understand than diodes.

A transistor is a nun that likes to dress up in Priest clothes.

A diode is a dude who enjoys his I/O.

Title: How does a keyboard actually work?
Post by: elservo on Sat, 16 October 2010, 03:37:49

Thanks for the link, Findecanor.  Keyboards make a bit more sense now.  Diodes are now a little more than just a word to me.

If only I could figure out how fish work, I would know EVERYTHING.