Article 13421 of sci.electronics:
From: (dennis armstrong)
Subject: Re: Seeking IR remote control specifications
Keywords: IR remote control
Date: 10 Jan 92 16:37:14 GMT

In <> (Robert Kelly) writes:

>I know there are a number of different systems for the
>infrared remote control of consumer electronics, for
>example video equipment, but I would like to try building
>some infrared-related gadgets and any information would
>be helpful.  What I'm looking for is timing information,
>control code definitions, etc.

The January 1992 issue of Elektor Electronics magazine (UK) has a construction
project to build a universal RC5 code infra-red receiver.

The RC5 code set was developed by Phillips and allows 2048 commands to be
transmitted divided into 32 addressable groups of 64 commands each.
The transmitted code consists of a 14 bit dataword of the following structure.
  2 run-in bits to adjust the AGC level in the receiver IC
  1 check bit
  5 system address bits
  6 command bits.

These have been assigned as follows:
System address     Equipment
  0                TV set
  2                Teletext
  5                Video recorder
  7                experimental
 16                preamplifier
 17                receiver/tuner
 18                tape/cassette recorder
 19                experimental

Command code      Function
 0-9               0-9
 12                standby
 13                mute
 14                presets
 16                volume +
 17                volume -                
 18                brightness +
 19                brightness -
 20                colour saturation +
 21                colour saturation -
 22                bass +
 23                bass -
 24                treble +
 25                treble -
 26                balance right
 27                balance left
 48                pause
 50                fast reverse
 52                fast forward
 53                play
 54                stop
 55                record
 63                system select

The basic timing is derived from a 36KHZ oscillator.
The code is transmitted in biphase format. In this system, a logic 1 is 
transmitted as a half bit time without signal, followed by a half bit time
with signal. A logic 0 has exactly the opposite structure. Each half bit 
consists of 32 shorter pulses. Each transmitted bit has a length of 1.778 msec,
the shorter pulses have a pulse width of 6.9444 usec on time and 20.8332 usec
off time. A complete dataword has a length of 24.889 msec, and is always
transmitted completely. If the key is held pressed the code is repeated in
intervals of 64 bit times (ie 113.778 msec).
The project uses the following ICs SAA3049 and TDA3048 in the receiver.

Transmitters use the following ICs SAA3006, SAA3010 and SAA3027.

You should be able to obtain spec sheets for these from your local Phillips
or Signetics (USA) chip suppliers.

Elektor Electronics 
Worldwide subscription services
unit 4
Gibbs Reed Farm  
Pashley Road
Fax UK(0580) 200616
Tel UK(0580) 200657

Hope this helps.

From: (Tim Channon)
Newsgroups: sci.electronics
Subject: Plans for serial-driven IR remote controller (finally!)
Date: 12 Jun 92 21:29:45 GMT

I'm not quoting that article!

Why no mention of RC5?

There is a list of codes allocated by the remote control committee, some 
mandatory, some not.

14 bit data word.
2 start bits for agc etc.
1 control bit to indicate a new transmission
5 system address bits
6 command bits

Bit period 1.778ms, repeat interval 64 bit periods 113.778ms

A one is a rising edge, a zero a falling edge (ignoring carrier).

Data transmitted msb first.

I'm not typing in all those codes!
CD seems to be sys addr 20.

Numbers 0..9 are codes 0..9, pause 48, stop 54, select system 63.


From: (Adam Goldberg)
Newsgroups: sci.engr,sci.engr.advanced-tv,,sci.electronics
Subject: Re: IR Remotes
Date: 5 Oct 93 14:00:28 GMT

In <> (Eric Olson) writes:

> (Matthew R. Singer) writes:

>>Remote controls for TVs and VCRs appear to use sets of standard codes,
>>or so one would judge from the way things like VCR Plus and generic
>>controllers work.

>I got one of the Radio Shack (sharp GP1U52X) IR detector modules.  
>I hooked the output to a scope and shot several of my Sony & Magnovox
>remotes at it.  I got a 12 bit pulse width modulated signal out.
>on for 500ns, then off for 750ns (logic 0) or 1250ns (logic 1) for each bit.
>So the remotes must take a 12 bit number, pulse width modulate it, then
>modulate it with the 40KHz carrier and blink it out the IR LED.
>(always wanted to make a card for my PC to read it in- someday....)

I am currently looking in to building a box which can send/receive IR
remote signals, hopefully I can send it commands via RS232 to, say,
turn on the TV, etc.

I received from Philips a set of data books 'Semiconductors for
Television and Video Systems' (3 books, books IC02a through IC02c),
and a photocopied article on IR remote signals.  

There seem to be two schemes for IR remotes: RC-5 (Philips-type), and
NEC type.  All I can really explain is the RC-5, because thats what I
have in front of me.

Bits are transmitted on a trailing edge, ie (pardon the ASCII) 

   |---+   |
   |   |   |
   |   |   |
   |   +---|
     Logic 0

   |   +---|
   |   |   |
   |   |   |
   |---+   |
     Logic 1

Each RC-5 code word is 14 bits, in the following format:  2 start
bits, the first is always 1, the second is a field bit denoting
command codes 0-63 (logical 1) or 64-127 (logical 0).  1 control bit
which toggles after each key release and initiates a new transmission
(ie, if you type 5, 5 on the first five this will be z, on the second
!z, to differentiate the second keystroke from just a retransmission
of the first), 5 system address bits for selecting one of 32 possible
systems listed in table 1.  6 command bits representing one of the 128
possible RC-5 commands listed in the tables at the end of the

"Before transmission via the IR LED, the HIGH period of each 1.778ms
symbol is modulated at 36kHz with a duty factor of 0.25.  Each
half-symbol period which is HICH therefore contains 32 pulses with an
on-time of 6.944us and a repetition period of 27.777us."

excerpts from table 1:

System #	Description:

0		TV1
1		TV2 (descrambler tuner)
3		TV1 or TV2 (commands 0-63 or 64-127)
5		VCR1
6		VCR2
16		Audio preamp
17		tuner
23		DAT

Command excerpts for a TV:

Command:	Description
16		Volume +
17		volume -
88		pip on/off
89		pip shift
90		pip/main swap
94		3/9 multiscan (search for 9 TV pictures and display in
			       9 pips)

and on and on and on.


PS: If anyone is interested in collaborating, this is what I have in
mind to build:

A box with on RS232 port, an IR receiver and IR transmitter.  It
should probably have some intelligence on board.  It can receive
signals from a remote (to program it, probably), and send some sort of
identification of what it received to the host via RS232.  It can then
receive this identification back via the RS232 and transmit it.

The idea is to be able to demonstrate to the box what signal means
what, then have the computer on the other end of the RS232 be able to
turn the TV on/off when on vacation, etc.

Adam G., or ...!uunet!mcrware!adamg
The above is not to be construed in any way as the official or unofficial
statements of Microware, or any Microware employees.