Re: [tuxdroid-user] RC5 again

[David B. <da...@ja...>]

On Fri, 13 Apr 2007 00:34:30 +0200, Philippe Teuwen <ph...@te...>  
wrote:

>
>> Or as I have plans to change that to be a kind of universal
>> receiver/emitter, the thing to do is sample the received code at a
>> higher frequency and send the raw data to the computer. That should
>> give us an idea of the signal your tux receives.
> I remember of a quite efficient way a program on my HP48 worked to act
> as universal remote:
> It encodes the stream as a succession of counter values, each of them
> being the duration of a receiving/non-receiving state. If a duration
> exceeds 256 then special value is used to code duration on more than one
> byte (thinks of UTF-8 coding style).
> The result still takes some bytes, could take quite a lot of time to
> transmit with the small packets of the radio :-/

I once found an application note of cypress that did just that, that's  
pretty neat imo. I'll try to find the link again.

> We could also have a look at the way lirc encodes learned codes and use
> directly that coding on the tux.

That's what I'd like to know before changing the IR emiter/receiver  
functions. We certainly want to benefit from lirc and there are already  
some simple homemade IR receivers for lirc. It's maybe better to do  
something compatible with that instead of having a custom coding and  
writing a specific lirc driver.

> BTW what is the IR receiver hardware? Does it demodulates already the
> 36kHz and outputs in TTL?
> In other words, do we have to sample the modulation or just the
> bits/Manchester-bits?

It uses a common IR receiver module which demodulates the 37.9kHz and  
outputs the logical signal bits directly. Actually it's the 940nm IR light  
wave which is modulated at 37.9kHz and pulsed with the logical signal for  
the coding and protocol which is RC5 here (manchester coding.)

david