[Arm-netbook] IC for analog and digital buttons (EOMA-68)

[Daniel Iglesias]

Hi everyone, Miguel brought me here :) Thanks for everyone's help and sorry if this message doesn't turn up in the proper thread or if the quotes are messed up since I'm not used to mailing lists.

> ------------------------------------------------------------------------
> On Mon, Jul 28, 2014 at 9:13 AM, Miguel Garcia <gacuest at gmail.com <http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook>> wrote:
> >  Peter Green is right. We need 6 ADCs.
> >
> >  2014-07-27 17:06 GMT+02:00 Luke Kenneth Casson Leighton <lkcl at lkcl.net <http://lists.phcomp.co.uk/mailman/listinfo/arm-netbook>>:
> >>   but you should be able to do keyboard matrix scanning to cover 16
> >>  buttons, 4 input 4 output... unless you really really want all
> >>  possible button combinations, hmmm...
> >>
> >>   are there any keys which may not be pressed together, so you can do
> >>  matrix-scanning on those, at least?
> >
> >  Matrix-scanning is not a good idea. We want all possible button combinations.
> 
>  thought so
> 
>  ok so you have an IC for the GPIO, and one for the ADC.

We could use two different IC's, but wouldn't using an appropriate microcontroller be a less complex solution? That would probably make the schematics and PCB easier to design, although having to develop the software for the uc is a big con. Plus those I2C expansion chips look pretty neat.

Some uc's in the ATtiny48 family have 6 ADCs and enough I/O pins. Also, while we're only considering what we need for user input, there may be other needs I don't know about (an extra ADC for battery monitoring? I have no idea). That would be a point in favor of using a uc.