[Arm-netbook] Keyboard

[Luke Kenneth Casson Leighton]

---
crowd-funded eco-conscious hardware: https://www.crowdsupply.com/eoma68


On Sat, Aug 27, 2016 at 6:54 PM, Vincent Legoll
<vincent.legoll at gmail.com> wrote:
> Hi,
>
> I don't know why, but I was kind of expecting this kind of answer ;-)

 :)

>>> Is the laptop's keyboard only option the
>>> Chicony P/N MP-03756GB-5287.
>>
>>  and associated variants, yes.
>
> In fact the question I had in mind was more:
>
> If there are such associated variants that can be (almost) drop-in
> replacement, but with backlighting...

 you need *exact* drop-in replacement, not "almost" - tolerances
are... what... 0.3mm so the keyboard doesn't fall out?  and the
connector really does have to be exact.

> Because I naively expected the producers to reuse their designs when
> adding such slight variations...
>
> So the answer is no... Too bad

 pretty mad, huh?

>>> Or maybe the laptop case can be modified to allow placement of a few
>>> leds around the screen that would get light on the keyboard. I had
>>> this on an old T42p and it was better than nothing.
>>
>>  that would be much simpler - it's still abouuut... 2-3 weeks of work,
>> redesigning casework
>
> Ouch, I was thinking of just one or two small holes in the casing, and friction
> slip the LEDs inside... I would not have expected this to take significant
> work. It could even be done by careful drilling, without redesign.

 it's best if you either run the 3D CAD stuff (see the youmagine
page), 3d-print a set out, then you'll have a clear idea.  you don't
really need to drill it (ok you could for a 1st revision).

>> that's assuming no LED circuits are needed and
>> there's a convenient place to draw power off of.  if it was under PWM
>> control of something (to change brightness) that's.. 3-5 weeks of PCB
>> design work and PCB assembly, 1-2 weeks of component sourcing and
>> verification.
>
> Here I show my almost complete lack of electronics-fu, I thought LEDs
> were so low power that they could get piggybacked to the display power
> line with just a 1K resistor added, and maybe a switch, to avoid needing
> to route a GPIO there just for that.

 the backlight's at 17v (appx) - LEDs are current-controlled not
voltage-controlled, they're not negligeable current, and you really
don't want to be overloading the power chip.

 l.