On Fri, Dec 9, 2011 at 6:11 PM, Dominique Dumont<dod@debian.org> wrote:
Hello Luke
Le Saturday 3 December 2011 22:36:41, vous avez écrit :
about the digital photo frame idea: that's an even simpler version of
a tablet, effectively. are you looking to build it yourself? if so,
below
No really build it myself.
great!
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"?
Then, we'd need to field test our device. This could be done with netbooks or
small tablets, but not with a bunch of boards and wires ;-) . We'd need ~ 10
of them to lend to family and neighbours and get feedbacks.
ok, well we have about 17 committed so far. the hardware development
costs (PCB, tooling) are about $USD 2,000. with 10 more, that would
be about $75 each for one (fully-populated, fully-functional but with
no external case) CPU card.
Once this is done, we'll need a small serie (~ 100 depending on price) to
really get serious.
ok, once the first $2000 of NREs is done, that's it: it doesn't have
to be paid again (NREs: non-recurring expenses. go figure).
subsequent PCBs therefore can be much reduced pricing.
Regarding the device, we'd need something quite standard. The screen should be
at least 800x600. Bigger would be better, but the device price for the small
serie will be the main limiting factor.
Regarding user input, I'm wondering if a touchscreen would not be better than
buttons behind the frame. Navigating in a menus with these rear buttons is not
user friendly. But buttons are needed in case customer loose the remote
control. May be a touchscreen as a fallback is better for users. Still
scratching head there.
an overlay resistive touchscreen is about $5, typically. they do
however require calibration: they're also sensitive to temperature,
humidity etc.
capacitive ones made of glass are *MORE* expensive than the
same-sized LCD! absolutely ridiculous, but that's the way it goes.
they're also heavier (because they have to be structurally strong).
there do exist plastic capacitive touchpanels, they're still in
development, the price _will_ come down... at some point.
bottom line is: touchscreens sound great until you look into the cost
and useability.
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.
the right kind of low-speed, low-resolution LCD panel (800x600,
800x480, 480x320 etc.) you could almost connect it up directly to the
EOMA-PCMCIA connector. if you didn't need a brightness control, that
would bring the cost down as well. the IR receiver you can get as a
USB device. if you kept it _that_ simple you'd hardly need a PCB at
all!
That would be better: I've not done HW design for a while (~ 20 years).
fortunately, electrons haven't changed charge or anything like that:
the speed of light is still the same constant, as best we are aware,
and V still equals I times R :)
l.
p.s. i've successfully compiled the allwinner a10 reference source
code, using the emdebian cross-compile toolchain.