--- crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68
On Sun, Jul 31, 2016 at 11:02 PM, Albert ARIBAUD <[email protected]> wrote: > Le Sun, 31 Jul 2016 21:56:13 +0100 > Luke Kenneth Casson Leighton <[email protected]> a écrit: > >> > Hmm... Not getting what you're hinting at. Can you develop? >> >> it's related to mis-detection of keys. if you press certain >> combinations in certain ways, you get "ghost" keys that you can't tell >> if they were actually pressed or not. by reducing the number of keys >> that are "live" (16 fan-in only activates up to 8 maximum where as 8 >> fan-in could activate up to 16 maximum) you reduce the possibility of >> "ghosting". >> >> there was an article online about it... ah! found it: >> http://pcbheaven.com/wikipages/How_Key_Matrices_Works/ > > Ok, got your point now. > > Too late today to do probabilities (heck, even in the morning right > after my coffee shot I would not trust my skills in probabilities). > Still, I intuitively (yeah, I know) think there is no reduction in the > risk of ghosting when transposing the matrix, because there is no > asymmetry in the ghosting problem; ghosting occurs as soon as three of > the four connections between two rows and two columns are closed: at > that point, there is no way to tell whether the fourth connection is > open or closed, and this, regardless of any notion of "row", "column", > or "activity". > > IOW, whether or not a given state of the keyboard matrix will exhibit > ghosting is only defined by the distribution of the depressed keys on > the matrix, not by the rotation with which we look at that matrix or > whether it currently has an active column. my point is: if you've activated 2x the amount of keys because you're firing on "rows" (16 activated) instead of "columns (only 8 activated), there's now 2x the chance of having a "ghosting" problem. i think. too much for my brain to cope with.... _______________________________________________ arm-netbook mailing list [email protected] http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook Send large attachments to [email protected]
