Re: Remote that breaks current system (was: IR: Port ene driver...) it.

[Jon S. <jon...@gm...>]

On Mon, Aug 2, 2010 at 11:12 AM, Jarod Wilson <ja...@re...> wrote:
> On Sat, Jul 31, 2010 at 05:53:33PM -0400, Jon Smirl wrote:
>> On Sat, Jul 31, 2010 at 2:51 PM, Andy Walls <aw...@md...> wrote:
> ...
>> > Since these two protocols have such close timings that systematic errors
>> > can cause misclassification when using simple mark or space measurements
>> > against fixed thresholds, it indicates that a more sophisticated
>> > discrimination mechanism would be needed.  Perhaps one that takes multiple
>> > successive measurements into account?
>>
>> If we get to the point where we need more sophisticated
>> classifications we can build it. But are we at that point yet? I'd
>> prefer to initially leave everything pretty strict as a way of
>> flushing out driver implementation bugs.
>>
>> Find some remotes and receivers that break the current system.
>
> Got one. The Streamzap PC Remote. Its 14-bit RC5. Can't get it to properly
> decode in-kernel for the life of me. I got lirc_streamzap 99% of the way
> ported over the weekend, but this remote just won't decode correctly w/the
> in-kernel RC5 decoder.

Manchester encoding may need a decoder that waits to get 2-3 edge
changes before deciding what the first bit. As you decode the output
is always a couple bits behind the current input data.

You can build of a table of states
L0 S1 S0 L1  - emit a 1, move forward an edge
S0 S1 L0 L1 - emit a 0, move forward an edge

By doing it that way you don't have to initially figure out the bit clock.

The current decoder code may not be properly tracking the leading
zero. In Manchester encoding it is illegal for a bit to be 11 or 00.
They have to be 01 or 10. If you get a 11 or 00 bit, your decoding is
off by 1/2 a bit cycle.

Did you note the comment that Extended RC-5 has only a single start
bit instead of two?

>
> Working:
> Streamzap receiver + RC6 (MCE) remote, in-kernel decoding
> Streamzap receiver + RC5 (Streamzap) remote, lirc decoding
>
> Not working:
> Streamzap receiver + RC5 (Streamzap) remote, in-kernel decoding
> MCE transceiver + RC5 (Streamzap) remote, in-kernel decoding
>
> Failure mode is identical between the two, leading me to believe my
> streamzap port is good to go, we just have an issue to track down with rc5
> decoding.
>
> Said failure mode is that RC5 fails at STATE_INACTIVE (0) with the initial
> space provided by both receivers, then gets rolling with (I believe) the
> first pulse. It then gets all the way to STATE_FINISHED, and bails,
> because it should be on a space there, but its on a pulse.
>
> I've twiddled the decoder to proceed even if its a pulse, but the
> resulting decoding is still no good, as multiple adjacent keys (which have
> proper decoded values that only differ by 1, per lirc decoding) get
> decoded to the same value as one another.
>
> Still poking around trying to figure out the problem, but here's what the
> (slightly modified to not bail when it gets to STATE_FINISHED with a
> pulse) rc5 decoder is seeing/doing:
>
> ir_rc5_decode: RC5(x) decode started at state 0 (4292819813us space)
> ir_rc5_decode: RC5(x) decode failed at state 0 (4292819813us space)
> ir_rc5_decode: RC5(x) decode started at state 0 (896us pulse)
> ir_rc5_decode: RC5(x) decode started at state 1 (7us pulse)
> ir_rc5_decode: RC5(x) decode started at state 1 (896us space)
> ir_rc5_decode: RC5(x) decode started at state 2 (1920us pulse)
> ir_rc5_decode: RC5(x) decode started at state 1 (1031us pulse)
> ir_rc5_decode: RC5(x) decode started at state 2 (1664us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (775us space)
> ir_rc5_decode: RC5(x) decode started at state 2 (1664us pulse)
> ir_rc5_decode: RC5(x) decode started at state 1 (775us pulse)
> ir_rc5_decode: RC5(x) decode started at state 2 (896us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (7us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (896us pulse)
> ir_rc5_decode: RC5(x) decode started at state 2 (896us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (7us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (896us pulse)
> ir_rc5_decode: RC5(x) decode started at state 2 (1664us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (775us space)
> ir_rc5_decode: RC5(x) decode started at state 2 (896us pulse)
> ir_rc5_decode: RC5(x) decode started at state 3 (7us pulse)
> ir_rc5_decode: RC5(x) decode started at state 3 (896us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (896us space)
> ir_rc5_decode: RC5(x) decode started at state 2 (1920us pulse)
> ir_rc5_decode: RC5(x) decode started at state 1 (1031us pulse)
> ir_rc5_decode: RC5(x) decode started at state 2 (1664us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (775us space)
> ir_rc5_decode: RC5(x) decode started at state 2 (1664us pulse)
> ir_rc5_decode: RC5(x) decode started at state 1 (775us pulse)
> ir_rc5_decode: RC5(x) decode started at state 2 (896us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (7us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (896us pulse)
> ir_rc5_decode: RC5(x) decode started at state 2 (1664us space)
> ir_rc5_decode: RC5(x) decode started at state 1 (775us space)
> ir_rc5_decode: RC5(x) decode started at state 2 (1920us pulse)
> ir_rc5_decode: RC5(x) decode started at state 4 (1031us pulse)
> ir_rc5_decode: RC5 usually ends w/space, wtf?
> ir_rc5_decode: RC5 scancode 0x1129 (toggle: 0)
> ir_getkeycode: unknown key for scancode 0x1129
>
> This was for the OK button on the remote, which in lircd, decodes to
> scancode 0x12 in the lower 6 bits, high 8 bits are 0xa3 for all buttons.
> At least, I think I'm decoding lircd.conf correctly. See here to be sure:
>
> http://lirc.sourceforge.net/remotes/streamzap/lircd.conf.streamzap
>
> --
> Jarod Wilson
> ja...@re...
>
>



-- 
Jon Smirl
jon...@gm...