e013050.PDF

GENERAL INTEREST

IR Remote Control

Codes (1)

formats, protocols and

(in)compatibility

By A.N. Other

There are so many different remote

control message formats currently in

use that it can all be a bit confusing. If you are experimenting with remote

controller IC’s then its important to know the different control protocols

used by each manufacturer. This article seeks to describe the most pop-

ular protocols in current use.

Its almost impossible to buy a TV today that

doesn’t have a IR remote controller and its

only when we temporarily mislay this device

that we realise how useful they are. Back in

1975 when the first remote controllers

appeared they used ultra sonic signals to

send the control information, these were later

superseded by the controllers that we are

familiar with today using infra red. The infra

red devices offer lower production costs, wide

operating range and good communication

security. A look inside a typical remote con-

troller will show that it consists of only one

IC. The IC interprets each key press and

sends a coded data signal to the transmitter

IR diode. A simple resonator is also used to

supply a stable clock. On the receiving side

in the equipment being controlled we ﬁnd a

IR detector and demodulator which is nor-

mally integrated into the same device. The

SFH505-xx family of devices from Siemens

contains the receiver, demodulator and out-

put driver so that the received data can be

connected directly to a micro controller or

control decoder. Unfortunately the actual con-

trol protocol used by each manufacturer are

mostly incompatible.

The IR message transmitted by the controller

is subject to interference from other

IR sources in the vicinity. These

include heaters, incandescent lamps

and other heat generators. One stan-

dard method of rejecting this

unwanted interference is to modulate

each transmitted bit with a stable

carrier frequency in the range of 30 to

40 kHz. Another method is the so-

called flash mode, this technique is

employed by the Plessey MV500 chip

(described in the February 1991 edi-

tion of Elektor Electronics ). This

method outputs data in the form of

17 µs short flashes of IR light fol-

lowed by different off periods. Nokia

also use this method with their

IRT1250 IC. This system has however

not gained wide acceptance and the

vast majority of remote controllers

use the modulation technique.

The accompanying oscilloscope

pictures show each of the described

transmission formats received by the

Temic TFMS5360 receiver IC. This

device is optimised for reception of a

signal modulated at 36 KHz but can

also detect other frequencies albeit

with a reduced range. In the upper

half of the picture a single telegram

is shown and in the lower half a con-

tinuous key-press is shown. The out-

put of the IC goes low when the

modulated signal is detected.

It is important to note that the

equipment manufacturer is entirely

at liberty to choose a transmitter

clock frequency and as such the tim-

ing given here may not be accurate

under all conditions. The timings of

pulse lengths may also be affected

by the sample clock in the

TFMS5360 and could have an error of

160 µs (Temic data sheet).

The communications formats

described are the most popular but

it does not represent all the possible

formats that you are likely to find.

Many firms have devised their own

control format, sometimes in order to

reduce costs or sometimes to incor-

porate different control features that

are not catered for with the existing

standards. If you use a mask pro-

grammable micro controller for cod-

ing and decoding you will be com-

Elektor Electronics

3/2001

GENERAL INTEREST

pletely at liberty to devise your own

protocol which may be more suited

to your own particular hardware of

software. This method also ensures

that a manufacturer will not need to

worry about licencing fees or possi-

ble patent infringement.

Some modern remote IR con-

trollers transmit the message a num-

ber of times using different message

formats. For example the controller

will ﬁrst send out the Japanese code

and then 50 ms later sends out the

same command but this time using

RC 5 code. The advantage here for

the equipment manufacturer is that

for future equipment development

you need not wait for a chip manu-

facturer to produce a controller using

a particular IR coding standard. It is

now possible to select the best or

cheapest integrated equipment con-

troller and be sure that the IR remote

controller will produce compatible

control signals.

So which manufacturer and which

coding system? This article

describes some of the most popular

IR coding standards currently in use.

(010023-1)

Code

Manufacturer

RECS80

Thomson, Nordmende

NEC

Harman/Kardon, Yamaha,

Canon

DENON

Denon

SIRCS

Sony

RC5

Loewe, Philips, Grundig,

Marantz

MOTOROLA

Grundig, Kathrein

JAPAN

Panasonic, Loewe

SAMSUNG

Samsung

DAEWOO

Daewoo

RC5 Code

The most widely used coding method for IR control in Europe

is the RC 5 code. This was originally developed by Philips and

has the capacity to send 2048 different commands. 32 address-

able groups each with 64 commands. Each piece of equipment

has its own address so that for example adjusting the volume

of your audio system will not affect the sound level of your TV.

One complete message has a length of 14 bits and is com-

posed of the following bits:

– 2 Start bits to control the AGC levels (Auto gain control) in

the receiver IC.

– 1 Toggle bit indicates that a new key is pressed.

– 5 System address bits

– 6 command bits

The toggle bit changes its value every time a new key is

pressed and is used to tell the difference between pressing

the key again and holding the key down. The ﬁve address bits

follow the toggle bit and indicate which piece of equipment is

being controlled. Lastly the six command bits contain the con-

trol information.

Figure 1. RC5 code at the output of the receiver IC TFMS5360.

Table 1 shows in decimal the correspondence between the

equipment and command codes used for this format.

RC5 code employs biphase encoding, One bit of data is rep-

resented by two half bits. A Low/High combination of these

bits indicates a data ‘1‘ whereas a High/Low combination indi-

cates a data ‘0‘ The length of each bit is 1.778 ms, and a com-

plete message is 24.889 ms long.

113.778ms

The RC5 code is probably the best documented protocol for

IR control and particularly interesting are the two free system

addresses 7 and 13 these are not allocated to any particular

equipment type but are reserved for experimental purposes.

Typical IC’s used for this message format are:

start bits toggle bit

address (bit 4 … bit 0)

command

24.889ms

889us

Transmitter:

SAA3006, SAA3010 (Philips)

HT6230 (Holtek)

"0"

"1"

010023 - 12

1778us

Figure 2. RC5 code message format (Address 1, command 28

shown).

Receiver:

SAA3009, SAA3049 (Philips)

3/2001

Elektor Electronics

GENERAL INTEREST

The RC5 codes:

Address Equipment

0 . . . . . . . . . . . . . . . . .TV1

1 . . . . . . . . . . . . . . . . .TV2

2 . . . . . . . . . . . . . . . . .Videotext

3 . . . . . . . . . . . . . . . . .Expansion for TV1 and TV2

4 . . . . . . . . . . . . . . . . .Laser Vision Player

5 . . . . . . . . . . . . . . . . .Video recorder1 (VCR1)

6 . . . . . . . . . . . . . . . . .Video recorder2 (VCR2)

7 . . . . . . . . . . . . . . . . .Reserved

8 . . . . . . . . . . . . . . . . .SAT1

9 . . . . . . . . . . . . . . . . .Expansion for VCR1 and VCR2

10 . . . . . . . . . . . . . . . .SAT2

11 . . . . . . . . . . . . . . . .Reserved

12 . . . . . . . . . . . . . . . .CD Video

13 . . . . . . . . . . . . . . . .Reserved

14 . . . . . . . . . . . . . . . .CD Photo

15 . . . . . . . . . . . . . . . .Reserved

16 . . . . . . . . . . . . . . . .Audio preampliﬁer1

17 . . . . . . . . . . . . . . . .Tuner

18 . . . . . . . . . . . . . . . .Analogue cassette recorder

19 . . . . . . . . . . . . . . . .Audio preampliﬁer2

20 . . . . . . . . . . . . . . . .CD

21 . . . . . . . . . . . . . . . .Audio Rack or Aufnahmegerät

22 . . . . . . . . . . . . . . . .Audio Satellite receiver

23 . . . . . . . . . . . . . . . .DCC Recorder

24 . . . . . . . . . . . . . . . .Reserved

25 . . . . . . . . . . . . . . . .Reserved

26 . . . . . . . . . . . . . . . .writable CD

27...31 . . . . . . . . . . . . .Reserved

92 . . . . . . . . . . . . . . . .Multi strobe (Date + for system 9)

93 . . . . . . . . . . . . . . . .Main frozen (Date – for system 9)

94 . . . . . . . . . . . . . . . .3/9 multi-scan (Start time + for system 9)

95 . . . . . . . . . . . . . . . .PIP select (Start time – for system 9)

96 . . . . . . . . . . . . . . . .Mosaic/multi-PIP (Record program + for system 9)

97 . . . . . . . . . . . . . . . .Picture DNR (Record program – for system 9)

98 . . . . . . . . . . . . . . . .Main stored (Alternate channel for system 9)

99 . . . . . . . . . . . . . . . .PIP strobe (Stop time + for system 9)

100 . . . . . . . . . . . . . . .Recall main picture (Stop time – for system 9)

101 . . . . . . . . . . . . . . .PIP freeze

102 . . . . . . . . . . . . . . .PIP step up +

103 . . . . . . . . . . . . . . .PIP step down –

118 . . . . . . . . . . . . . . .Sub mode

119 . . . . . . . . . . . . . . .Options sub mode

123 . . . . . . . . . . . . . . .Connect

124 . . . . . . . . . . . . . . .Disconnect

Special commands for equipment addresses 0 und 1 (TV1 / TV2) :

Code Key Function

10 . . . . . . . . . . . . . . . .1/2/3 digits / 10

11 . . . . . . . . . . . . . . . .Freq./prog./ch./11

12 . . . . . . . . . . . . . . . .Standby

13 . . . . . . . . . . . . . . . .Mute/de-mute

14 . . . . . . . . . . . . . . . .Personal pref.

15 . . . . . . . . . . . . . . . .Display

28 . . . . . . . . . . . . . . . .Contrast +

29 . . . . . . . . . . . . . . . .Contrast –

30 . . . . . . . . . . . . . . . .Search +

31 . . . . . . . . . . . . . . . .Tint/hue –

32 . . . . . . . . . . . . . . . .Ch./prog. +

33 . . . . . . . . . . . . . . . .Ch./prog. –

34 . . . . . . . . . . . . . . . .Altern./ch.

35 . . . . . . . . . . . . . . . .? language

36 . . . . . . . . . . . . . . . .Spatial stereo

37 . . . . . . . . . . . . . . . .Stereo/mono

38 . . . . . . . . . . . . . . . .Sleep timer

39 . . . . . . . . . . . . . . . .Tint/hue. +

40 . . . . . . . . . . . . . . . .RF switch

41 . . . . . . . . . . . . . . . .Store/execute/vote

42 . . . . . . . . . . . . . . . .Time

43 . . . . . . . . . . . . . . . .Scan fwd./increm.

44 . . . . . . . . . . . . . . . .Decrement

46 . . . . . . . . . . . . . . . .Sec con/menu

47 . . . . . . . . . . . . . . . .Show clock

48 . . . . . . . . . . . . . . . .Pause

49 . . . . . . . . . . . . . . . .Erase/correct

50 . . . . . . . . . . . . . . . .Rewind

51 . . . . . . . . . . . . . . . .Go to

52 . . . . . . . . . . . . . . . .Wind

53 . . . . . . . . . . . . . . . .Play

54 . . . . . . . . . . . . . . . .Stop

55 . . . . . . . . . . . . . . . .Record

56 . . . . . . . . . . . . . . . .External 1

57 . . . . . . . . . . . . . . . .External 2

59 . . . . . . . . . . . . . . . .Advance

60 . . . . . . . . . . . . . . . .TXT sub-mode/12

61 . . . . . . . . . . . . . . . .Sys. Standby

62 . . . . . . . . . . . . . . . .Crispener

70 . . . . . . . . . . . . . . . .Speech/music

79 . . . . . . . . . . . . . . . .Sound scroll

104 . . . . . . . . . . . . . . .PIP size

105 . . . . . . . . . . . . . . .Pic. Scroll

106 . . . . . . . . . . . . . . .Act. On/off

107 . . . . . . . . . . . . . . .Red

108 . . . . . . . . . . . . . . .Green

109 . . . . . . . . . . . . . . .Yellow

110 . . . . . . . . . . . . . . .Cyan

111 . . . . . . . . . . . . . . .Index/white

112 . . . . . . . . . . . . . . .Next

113 . . . . . . . . . . . . . . .Previous

122 . . . . . . . . . . . . . . .Store open/close

126 . . . . . . . . . . . . . . .Movie expand

127 . . . . . . . . . . . . . . .Parental access

keycodes:

Code Key Function

0 . . . . . . . . . . . . . . . . .0

1 . . . . . . . . . . . . . . . . .1

2 . . . . . . . . . . . . . . . . .2

3 . . . . . . . . . . . . . . . . .3

4 . . . . . . . . . . . . . . . . .4

5 . . . . . . . . . . . . . . . . .5

6 . . . . . . . . . . . . . . . . .6

7 . . . . . . . . . . . . . . . . .7

8 . . . . . . . . . . . . . . . . .8

9 . . . . . . . . . . . . . . . . .9

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

63 . . . . . . . . . . . . . . . .System select

71 . . . . . . . . . . . . . . . .Dim local display

77 . . . . . . . . . . . . . . . .Linear function increment

78 . . . . . . . . . . . . . . . .Linear function decrement

80 . . . . . . . . . . . . . . . .Step up

81 . . . . . . . . . . . . . . . .Step down

82 . . . . . . . . . . . . . . . .Menu on

83 . . . . . . . . . . . . . . . .Menu off

84 . . . . . . . . . . . . . . . .Display A/V system status

85 . . . . . . . . . . . . . . . .Step left

86 . . . . . . . . . . . . . . . .Step right

87 . . . . . . . . . . . . . . . .Acknowledge

88 . . . . . . . . . . . . . . . .PIP on/off (Pay TV channel + for system 3)

89 . . . . . . . . . . . . . . . .PIP shift (Pay TV channel - for system 3)

90 . . . . . . . . . . . . . . . .PIP / main swap (Radio channel + for system 3)

91 . . . . . . . . . . . . . . . .Strobe on/off (Radio system – for channel 3)

Elektor Electronics

3/2001

GENERAL INTEREST

SIRCS/Control S Code

error is detected. SIRCS message coding is identical to CNTRL

S, but SIRCS modulates the code at 40 kHz ready to be sent to

an IR diode. CNTRL-S is the baseband (unmodulated) signal

and is used between equipment where a communications

cable is ﬁtted. Sony produce the following IC:

Transmitter:

KIE RA275 S42

Figure 3. SIRCS code at the output of the TFMS5360 receiver

IC.

45ms

A message sent using the SIRCS or CNTRL S protocol from

Sony consists of twelve to twenty bits. Five to thirteen of these

bits is used for the address field and seven bits for the key

code.

A Start bit (2.4 ms) is sent followed by a 0.6 ms space or

pause. Next comes the data. A ’1’ is represented by a 1.2 ms

ON or mark followed by a 0.6 ms OFF or pause. A ’0’ is repre-

sented by a 0.6 ms ON and a 0.6 ms OFF. A typical message

is shown in Figure 4 . The message is sent a minimum of twice

(five times for a camcorder). The message is discarded if an

2.4ms 0.6 ms

start bit

2 command (bit 0 … bit 6)

address (bit 0 … bit 4)

ext. +3...8 bit

0.6ms

1.2ms

"0"

"1"

010023 - 14

1.2ms

1.8ms

Figure 4. CNTRL-S and SIRCS message format.

The Sony

008 . . . . . . . . . . . . . . .9 button

009 . . . . . . . . . . . . . . .10 button/0 button

011 . . . . . . . . . . . . . . .Enter

016 . . . . . . . . . . . . . . .Channel up

017 . . . . . . . . . . . . . . .Channel down

018 . . . . . . . . . . . . . . .Volume up

019 . . . . . . . . . . . . . . .Volume down

020 . . . . . . . . . . . . . . .Mute

021 . . . . . . . . . . . . . . .Power

022 . . . . . . . . . . . . . . .Reset TV

023 . . . . . . . . . . . . . . .Audio mode:

mono/SAP/stereo

024 . . . . . . . . . . . . . . .Picture up

025 . . . . . . . . . . . . . . .Picture down

026 . . . . . . . . . . . . . . .Colour up

027 . . . . . . . . . . . . . . .Colour down

030 . . . . . . . . . . . . . . .Brightness up

031 . . . . . . . . . . . . . . .Brightness down

032 . . . . . . . . . . . . . . .Hue up

033 . . . . . . . . . . . . . . .Hue down

034 . . . . . . . . . . . . . . .Sharpness up

035 . . . . . . . . . . . . . . .Sharpness down

036 . . . . . . . . . . . . . . .Select TV tuner

038 . . . . . . . . . . . . . . .Balance left

039 . . . . . . . . . . . . . . .Balance right

041 . . . . . . . . . . . . . . .Surround on/off

042 . . . . . . . . . . . . . . .Aux/Ant

047 . . . . . . . . . . . . . . .Power off

048 . . . . . . . . . . . . . . .Time display

054 . . . . . . . . . . . . . . .Sleep timer

058 . . . . . . . . . . . . . . .Channel display

059 . . . . . . . . . . . . . . .Channel jump

064 . . . . . . . . . . . . . . .Select input video1

065 . . . . . . . . . . . . . . .Select input video2

066 . . . . . . . . . . . . . . .Select input video3

074 . . . . . . . . . . . . . . .Noise reduction on/off

078 . . . . . . . . . . . . . . .Cable/broadcast

079 . . . . . . . . . . . . . . .Notch ﬁlter on/off

088 . . . . . . . . . . . . . . .PIP channel up

089 . . . . . . . . . . . . . . .PIP channel down

091 . . . . . . . . . . . . . . .PIP on

092 . . . . . . . . . . . . . . .Freeze screen

094 . . . . . . . . . . . . . . .PIP position

095 . . . . . . . . . . . . . . .PIP swap

096 . . . . . . . . . . . . . . .Guide

097 . . . . . . . . . . . . . . .Video setup

098 . . . . . . . . . . . . . . .Audio setup

099 . . . . . . . . . . . . . . .Exit setup

107 . . . . . . . . . . . . . . .Auto program

112 . . . . . . . . . . . . . . .Treble up

113 . . . . . . . . . . . . . . .Treble down

114 . . . . . . . . . . . . . . .Bass up

115 . . . . . . . . . . . . . . .Bass down

116 . . . . . . . . . . . . . . .+ key

117 . . . . . . . . . . . . . . .– key

120 . . . . . . . . . . . . . . .Add channel

121 . . . . . . . . . . . . . . .Delete channel

125 . . . . . . . . . . . . . . .Trinitone on/off

127 . . . . . . . . . . . . . . .Displays a red RtestS

on the screen

codes:

Equipment address codes (decimal):

Address Equipment type

1 . . . . . . . . . . . . . . . . .TV

2 . . . . . . . . . . . . . . . . .VTR1

4 . . . . . . . . . . . . . . . . .VTR2

6 . . . . . . . . . . . . . . . . .Laserdisc

7 . . . . . . . . . . . . . . . . .VTR2

11 . . . . . . . . . . . . . . . .VTR3

12 . . . . . . . . . . . . . . . .Surround sound

processor

16 . . . . . . . . . . . . . . . .Cassette deck, tuner

17 . . . . . . . . . . . . . . . .CD Player

18 . . . . . . . . . . . . . . . .Equaliser

164 . . . . . . . . . . . . . . .TV digital effects

(8 bit device code)

keycodes:

code key Function

000 . . . . . . . . . . . . . . .1 button

001 . . . . . . . . . . . . . . .2 button

002 . . . . . . . . . . . . . . .3 button

003 . . . . . . . . . . . . . . .4 button

004 . . . . . . . . . . . . . . .5 button

005 . . . . . . . . . . . . . . .6 button

006 . . . . . . . . . . . . . . .7 button

007 . . . . . . . . . . . . . . .8 button

3/2001

Elektor Electronics

GENERAL INTEREST

RECS80 Code

this time period will be represented by a burst of carrier fre-

quency. If conﬁgured to ﬂash mode the IR transmitter will be

flashed on at this time. A ‘0’ has a space of 5.06 ms while a

‘1’ has a space of 7.60 ms (derived from a 455 kHz resonator in

the remote control transmitter). Although the length of the

data packet is dependent on the commands sent, the time

between two messages is ﬁxed at 121 ms. The modulation fre-

quency is 38 kHz.

Typical ICs for remote control:

Transmitter:

SAA3004, SAA3007 and SAA3008 (Philips)

M3004, M3005, M3006 (ST Microelectronics)

Figure 5. RECS80 code at the output of the TFMS5360 receiver

IC.

Receiver:

SAA3009, SAA3049 (Philips)

The RECS80 code from Philips a pulse position modulation

technique. With this system a ﬁxed length pulse of light is fol-

lowed by a variable length space. The space timing conveys

the data. There are 1280 possible codes divided into 64 com-

mands and 20 subsystems. A subsystem is simply the type of

equipment being controlled i.e. a TV or a VCR. A message is

composed of 11 bits. The ﬁrst two bits are the toggle bits fol-

lowed by three sub-system address bits and six data bits,

these indicate which key was pressed. The toggle bits are

incremented if a key is released for a minimum time but will

remain unchanged within a multiple key-stroke sequence. If

the transmitter is configured to operate in modulated mode

the ﬁrst toggle bit is replaced by a REF bit of ﬁxed duration.

In the lower trace of Figure 15 not all the data is shown

because of the low sampling rate of the scope some of the bits

have been missed. The RECS80 protocol encodes the data by

variable length spaces between constant width ON pulses

(140.8 µs). If the transmitter is conﬁgured to modulation mode

60ms

8ms

4ms

start bit

address (bit 0 … bit 7)

command

stop bit

0.55ms

"0"

"1"

010023 - 26

1ms

2ms

Figure 6. RECS80 code message format

Internet Links

Nec Format:

http://www.princeton.com.tw/spechtml/remote/2221.htm

Philips semiconductor:

http://www.semiconductors.com

www-us.semiconductors.com/pip/SAA3049AP

Motorola Home-Page:

http://motorola.com

Motorola-Format:

http://holtek.com

Next month:

– NEC

– DENON

– MOTOROLA

– JAPAN

– SAMSUNG

– DAEWOO

Samsung Home-Page:

http://www.intl.samsungsemi.com/System_LSI/Microcontroller/Product_Guide

/Microcontroller/product_guide.html

Elektor Electronics

3/2001

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