🚀 go-pugleaf

In article <3090@utai.UUCP> dudek@utai.UUCP (Gregory Dudek) writes:
>
>    I have a SONY TV at home with a RM-729 remote control. 
>    What I'd like to do is build a decoder so that I could control other
>    things with the same remote control.

	The easiest way to do this is to get a schematic for the TV from
a distributor that handles Sony service information and duplicate the
remote control circuitry from the TV with appropriate modifications to
control whatever you have in mind.

	This will inevitably mean that you use either one or two of the
ICs Sony uses to decode the remote control information.  They should
be available from the distributor at the usual slightly outraguous
prices Sony charges.  Duplicating the same functionality in MSI TTL
is not easy (and would mean many chips), your only real alternative to
their chips is to implement a decoder using the preamplifier/demodulator chip
and do your own decoding of the digital data with a dedicated microprocessor.

	If you choose to use the dedicated micrroprocessor approach you
might find using a logic analyzer (borrow one over a weekend from work)
to look at the bit patterns emitted by the remote control would
make your life much easier as many IR remote controls only send
the command information once when you press a button. I believe the
data is prefixed with a remote control type code that allows the
receiver to reject commands for someone elses TV or VCR.

	{any remote controls use a bursts of light pulses at between 40
and 70 0 khz to encode a space(or one bit) and no light to encode a mark
(or zero bit); the actual data is send as either manchester coding
(like a single density floppy) or mfm (like a quad density floppy) at about
1000 bits per second.  The data format will consist of a start bit and
some fixed preamble bits (the control type code) followed by a 
command code (which button you pushed)

	Obviously the easiest way to decode the data is to use the
chip Sony uses and figure out what its outputs are.  This may be easy to
do for one or two outputs, some of the others may be in a more complex
format that is not as easy to access.  (If you do the logical thing
and poke around in the TV with a scope to see what the interface signals are 
remember - MANY TV's have one side of the power line tied to the
chassis and can KILL YOU if you aren't careful to use an isolation
transformer). 

	Good luck.
-- 
          David I. Emery   Charles River Data Systems
983 Concord St., Framingham, MA 01701 (617) 626-1102 uucp: decvax!frog!die