Re: Debian GNU/Linux on tablet hardware
On Tue, Dec 13, 2011 at 12:53 PM, Dominique Dumont <dod@debian.org> wrote:
> On Saturday 10 December 2011 02:01:51 Luke Kenneth Casson Leighton wrote:
>> batteries / power. ah. when you say "digital photo frame", do you
>> mean "portable device" or do you mean "put it on the wall or
>> mantlepiece"?
>
> I mean always on power socket. No batteries
whewww :)
> This thread started on tablet hardware. Do you have a price range for such a
> device ? (i.e. with screen and case)
achh... mass-volume pricing? 7in 800x480 LCDs are around $12, a case
would be around... $2 if that. motherboard (in this instance) 2-layer
single-sided including components: probably about... $2.50. bits from
the EOMA-PCMCIA card: about $15 - total comes to about $30 to $35.
it's the lack of a battery (in this instance) that does it (normally
an extra $6 to $10 or so). non-mass-volume pricing would
approximately double things.
profit, tax, shipping etc. usually adds at least 100% on top.
>> an overlay resistive touchscreen is about $5, typically. they do
>> however require calibration: they're also sensitive to temperature,
>> humidity etc.
>
> ok I've seen this kind of device while repairing my kid's gameboy.
achh, pffh, if you've handled those, you're onto a winner - you know
the score. btw you can actually get 7in LCDs which have resistive
touchpanels already attached.
>> bottom line is: touchscreens sound great until you look into the cost
>> and useability.
>
> The alternative is a remote control. Generic ones are used to navigate in
> menus. But this is not user friendly for older people. I'm thinking about
> having a more specific remote control, but I'm worried about the development
> cost (PCB, plastic molds...)
the PCB is peanuts. the circuit's simple enough to use a breadboard.
i think... you _may_ get away with an LCD Driver IC that has legs
(DIP) - can't remember the name of the one that's so low-cost that
everyone keeps using it, even though it's not SMT, it does
voltage-multiplying up to 28v, for arrays of LED backlights.... achh,
apologies.
you do _not_ want to go down the route of having your own case
manufactured. find a box that is "close enough", or spend vast
amounts of time finding something off-the-shelf. despite spending
vast amounts of time, it is guaranteed to be less money than paying to
have a case developed.
if you do not believe this, please review the openpandora blogs.
another option for low-volume is acrylic (which is clear), then paint
it. specialcomp got a case designed that way for the beagleboard.
>> there are some options however for very coarse-grained touchscreens.
>> if you can get away with "button-sized" fixed areas (such as used on
>> microwave ovens) then costs are dramatically reduced.
>
> I guess that such buttons could be drawn on the screen when required. One
> touch anywhere will trigger drawing buttons on screen.
yes - and if you keep it coarse-grained enough, you shouldn't need to
do too much in the way of calibration of the resistive touchpanel.
calibration is only kinda needed if you want millimetre / centimetre
accuracy. if you only care about "the top quadrant" you're laughing.
l.
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