[Arm-netbook] IR controller in Allwinner 10

[jonsmirl at gmail.com]

On Sat, Jan 7, 2012 at 12:39 PM, lkcl luke <luke.leighton at gmail.com> wrote:
> On Sat, Jan 7, 2012 at 4:17 PM, jonsmirl at gmail.com <jonsmirl at gmail.com> wrote:
>> On Sat, Jan 7, 2012 at 11:03 AM, Iliya Georgiev <ikgeorgiev at gmail.com> wrote:
>>> I found on Allwinners site a diagram showing the A1X chip family has an
>>> infrared controller. It can be useful for remote control device if someone
>>> wants to use the product as IPTV.
>>
>> It is probably IRDA which is a way tablets communicate data. That is
>> incompatible with consumer IR.
>>
>> A GPIO timer pin works just fine as an interface to an IR receiver
>> chip. The IR receiver chip demodulates the IR signal down to baseband.
>> Then the timer GPIO times the edge transitions. The timing of the edge
>> transitions is fed into the kernel's IR subsystem.
>
>  ... at which point, it would be possible to support, in software,
> absolutely any protocol rather than the one dictated by the hard-coded
> decision made for the CPU.

Note that this has to be a hardware timer pin. The kind that will give
you the number of microseconds between edges. It is too hard to time
these pulses completely in software. Not all GPIO pins are the same.
Only a few will have the timer interrupt capability. You want them to
interrupt on each edge and then record the number of microseconds in a
FIFO that is gets passed to the kernel's IR subsystem.

>  [thanks for answering this jon]
>
>  Iliya, hi,
>
>  here is where the pinouts for the expansion header are being
> evaluated, see section "Features".
>  http://rhombus-tech.net/allwinner_a10/orders/
>
>  each set of pins on the expansion header is *only* going to be
> accessible when the PCB is used for "factory installation" purposes or
> for R&D, experimentation or other small-volume (under 10,000 units)
> purposes.
>
>  that having been said, i'm looking for compelling reasons to include
> specific features on it - as well as compelling reasons to add an
> extra expansion header.
>
>  btw there is now a list of the full pinouts descriptions in the kicad
> library component at http://git.rhombus-tech.net/eoma
>
>  to help with that evaluation i've created a pinouts page which has an
> overview of the functions (including multiplexed ones) of each pin
> group.
>
>  l.
>
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-- 
Jon Smirl
jonsmirl at gmail.com