Orthogonal matrix PS/2 kbd controller, low-power?
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From: msg on 7 Jul 2008 10:46 I need to make a wearable PS/2 keyboard (one-off) and would like some input to help me decide between some inconvenient alternatives. The device needs to be small enough to wear comfortably strapped to an arm, have keys with positive action and not too closely spaced so as to require a stylus to depress. I have one candidate already made; a cash-register programming keyboard by TEC, which is just an orthogonal matrix of 5 rows by 12 columns, arranged as QWERTY plus specials, but there seems to be no OTS controller chip that can be easily adapted as all seem to scramble the matrix for whatever reasons (phantom key handling, rollover statistics, etc???). I have cannibalized a number of 101/102/104 AT PS/2 keyboards and found each to have used a different matrix arrangement; I picked the controller from one with the lowest stated quiescent power consumption and vowed to try and slice and dice the TEC matrix to adapt to it, but the task is daunting. I also considered making a new keyboard using ALPS micro-pushbutton switches salvaged from a variety of consumer digital equipment (found in everything from mice to laser printer front panels) and wire-wrapping the interconnects on the longish leads to accommodate the salvaged controller. I don't have PIC dev systems or tools or those for any other lower power MCU for that matter, nor really the time to ramp up for a one- off project like this. Does anyone here have some code for a low power part that permits key assignments to accommodate my ortho matrix? Does anyone happen to have one of a few vendors 'wrist keyboards' that they no longer need? Thanks, Michael
From: larwe on 7 Jul 2008 12:35 On Jul 7, 10:46 am, msg <msg@_cybertheque.org_> wrote: > power part that permits key assignments to accommodate my ortho matrix? > Does anyone happen to have one of a few vendors 'wrist keyboards' I have some Palm keyboards which would be about the size of a deck of playing cards and have a serial output. But why don't you buy a $10 rubber "rollup" keyboard off eBay and attach a couple of velcro strips to it?
From: msg on 7 Jul 2008 12:55 larwe wrote: > On Jul 7, 10:46 am, msg <msg@_cybertheque.org_> wrote: > > >>power part that permits key assignments to accommodate my ortho matrix? >>Does anyone happen to have one of a few vendors 'wrist keyboards' > > > I have some Palm keyboards which would be about the size of a deck of > playing cards and have a serial output. But why don't you buy a $10 > rubber "rollup" keyboard off eBay and attach a couple of velcro strips > to it? Those rubber rollups were the first option I investigated, but strapping a 16 inch long dead fish to my arm and trying to get positive key action from same didn't seem too appealing. I suppose I could make a backboard for it but then why not just strap a conventional keyboard somewhere, perhaps to a leg? Years ago there were some cute little PS/2 keyboards by Dauphin for handhelds but they have vanished from commerce; two vendors currently offer some tiny militarized 5 inch long wearables starting at about $375.00. Earlier this year there was a thread about building a positive-action keyboard; I just wondered if the O.P. may have coded a controller with code that could be adapted for my project. Michael
From: msg on 7 Jul 2008 13:17 msg wrote: > larwe wrote: <snip> >> But why don't you buy a $10 >> rubber "rollup" keyboard off eBay and attach a couple of velcro strips >> to it? > > > Those rubber rollups were the first option I investigated... <snip> Also, they certainly aren't marketed as low-power, all of the ones with stated figures show 250ma; my scrap controller states 50ma with all LEDs lit (I have yet to measure with LEDs off, but suspect somewhere around 10ma). The mini militarized keyboards have fancy power management modes and quiesce at some microamp range. Michael
From: Guy Macon on 7 Jul 2008 14:47
msg wrote: >I need to make a wearable PS/2 keyboard (one-off) and would like >some input to help me decide between some inconvenient alternatives. >The device needs to be small enough to wear comfortably strapped to >an arm, have keys with positive action and not too closely spaced >so as to require a stylus to depress. I have one candidate already >made; a cash-register programming keyboard by TEC, which is just >an orthogonal matrix of 5 rows by 12 columns, arranged as QWERTY >plus specials, but there seems to be no OTS controller chip that >can be easily adapted as all seem to scramble the matrix for >whatever reasons (phantom key handling, rollover statistics, etc???). > >I have cannibalized a number of 101/102/104 AT PS/2 keyboards and >found each to have used a different matrix arrangement; I picked >the controller from one with the lowest stated quiescent power >consumption and vowed to try and slice and dice the TEC matrix >to adapt to it, but the task is daunting. > >I also considered making a new keyboard using ALPS micro-pushbutton >switches salvaged from a variety of consumer digital equipment >(found in everything from mice to laser printer front panels) and >wire-wrapping the interconnects on the longish leads to accommodate >the salvaged controller. > >I don't have PIC dev systems or tools or those for any other lower >power MCU for that matter, nor really the time to ramp up for a one- >off project like this. Does anyone here have some code for a low >power part that permits key assignments to accommodate my ortho matrix? >Does anyone happen to have one of a few vendors 'wrist keyboards' >that they no longer need? You could do it all with a BasicX-24 [ http://www.basicx.com/ ] $99.95 for the chip plus development kit, and it is very esy to bang out code for one-off projects like yours. -- Guy Macon <http://www.GuyMacon.com/> |