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Protocol 3
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Attributed to: bbb@kuhub.cc.ukans.edu (Brett Bennett)
Description:
I can tell you about what I call the "Japanese-Format."(JF)
I call it this because my VCR (Toshiba) and my Stereo
(Pioneer) both use the same format, while my TV (RCA) uses a
completely different format. It would be interesting to see
if other Japanese manufactures are using same format as
well. As I'll explain in a moment, the JF allows for 256
different devices to be controlled, so it is possible that
each manufacture could have been allocated a range of
numbers. Then again it might just be coincidence. A
picture would really help here, but I'm not up to trying to
draw an ASCII graphic.
The JF consists of 3 parts. The first part is what I'll
call the preamble. It is a 8 ms wide pulse of the carrier
followed by 4 ms of no carrier. ( In case you don't already
know the carrier is an IR light beam modulated at 40 KHz. My JF
equipment uses 40 KHz , while my RCA TV uses about a 36 KHz
carrier. This made my IR controller that I built more
complicated because the difference was enough that I
couldn't use as single time base. More on the controller
later.) The second part of the code is 16 bits of data.
The first 8 bits are what I call the Device Code(DC),followed
8 bits that are the logical not of the preceeding 8 bits(DC).
(This apparently is used as a checksum to insure data validity.
and protect against random noise.)
The third part is 16 more bits of data, the first 8 being
what I call the Function Code (FC). This FC is then followed by
its logical NOT as was the DC.
This provides the ability to control up to 256 different devices,
each having up to 256 functions. There appear to even be some
special sequences, like for my CD deck, which consists of two JF
frames back to back that cause special functions to occur.
In general however, most functions are controlled with a
single JF frame.
The timing of the data is as follows:
Each bit cell is proceeded by an IR pulse that is about .6
ms long (600us). It is then followed by a no-carrier period
that is ether .4ms long or 1.2ms long. A zero is sent if
the off period is .4ms, and one is sent if the off period is
1.2 ms. Another way of thinking about it is, a 0 is bit cell
who's total time is about 1 ms, and a 1 is a bit cell who's
total time is about 2 ms, i.e. pulse period modulation.
The DC and FC are sent LSB first. So in time it looks like:
DC LSB->MSB, NOT-DC LSB-MSB , FC LSB-MSB , NOT-FC LSB-MSB
The DCs I know are: (all numbers in hex)
A5 Pioneer amp
A4 Pioneer tuner
A2 Pioneer CD
A1 Pioneer cassette deck.
(I've wondered what A3 might be, open reel tape deck
perhaps)
44 Toshiba SV-771 VCR
The FCs share great commonalty across 8]
E-mail: 
info@telesys.ru
