Vishay Semiconductors
`Data Formats for IR Remote Control
`
`VISHAY
`
`In most remote control transmission systems, only
`small data rates are transmitted to control the func-
`tions of home entertainment equipment. Most impor-
`tant is the safety of transmission where an incorrect
`interpretation of the transmitted code is not permissi-
`ble. Unintelligible signals must be ignored. Usually,
`commands are repeated until the remote controlled
`device reacts as desired. The operator can directly
`observe the result of pressing a key by visual feed-
`back.
`Because IR signals do not exit a room and because
`there is only a short period of data transmitting at
`each keypress there is no necessity for legal guide-
`lines of the coding in the frequency band between
`30 kHz and 56 kHz and also at 455 kHz.
`
`Some methods of modulation have been established.
`In order to achieve reliable and battery power saving,
`transmission bursts of the carrier frequency are trans-
`mitted. This is called "Pulse Code Modulation" (PCM).
`The three commonly used representations of one bit
`in remote control systems are described in the follow-
`ing diagrams.
`The "Bi Phase Coding" has one rising or falling edge
`in the centre of each time chip (Figure 1). In the "Pulse
`Distance Coding" all bursts have the same length but
`the time between the bursts is different depending on
`the value of the bit (Figure 2). In the "Pulse Length
` Code" there are two kinds of burst lengths depending
` on the bit value (Figure 3).
`.
`
`"1"
`
`"1"
`
`"0"
`
`"0"
`
`"0"
`
`"0"
`
`"1"
`
`"1"
`
`17049
`
`Figure 1. BI phase coding ( a rising edge within a time window is equivalent to a “1“, a falling edge represents a “0“)
`
`.
`
`"0"
`
`"1"
`
`"0"
`
`"1"
`
`"0"
`
`17050
`
`Figure 2. Pulse distance coding
`
`17051
`
`"1"
`
`" 0"
`
`"1"
`
`"1"
`
`" 0"
`
`Figure 3. Pulse length coding
`
`www.vishay.com
`1
`
`Document Number: 80071
`Rev. A2, 27-Aug-03
`
`Roku EX1025
`U.S. Patent No. 9,716,853
`
`

`

`VISHAY
`
`The Vishay IR receiver modules are developed and
`optimized for use in such carrier frequency burst
`transmission. Standard types are available for the fre-
`quencies 30 kHz, 33 kHz, 36 kHz, 36.7 kHz, 38 kHz,
`40 kHz, 56 kHz and 455 kHz. Other frequencies in
`this range can be realized on request.
`Beside the different kinds of coding and the different
`carrier frequencies there are further variations of data
`formats with and without preburst, with different num-
`bers of bits in a command and with different bit
`lengths.
`Almost all codes have address bits and data bits. For
`safety reasons some codes send the data twice
`(inverted and noninverted). Usually the data com-
`mand is sent (repeated) as long as the key is pressed.
`There are different ways to overcome the difficulty of
`distinguishing between a multiple key pressing and
`an interruption of the transmission link (e.g. to avoid
`the TV selecting channel "11" when channel "1" is
`expected). Some codes use a toggle bit which
`change the value at each keypress, some codes send
`an indication for start and stop at the beginning and at
`
`Vishay Semiconductors
`
`the end of each keypress and some codes send the
`data only once at each keypress.
`Two common data formats are described more in
`detail here: the RC5 Code and the NEC Code.
`
`The RC 5 Code:
`In the RC 5 standard, a bi-phase coding is applied
`(see Figure 4). The carrier frequency is fixed at
`36 kHz.
`The transmission of a word begins with two start bits,
`followed by a toggle bit. The toggle bit changes its
`value at each key operation. The five address bits
`represent the address of the device to be controlled.
`The six command bits contain the information to be
`transmitted.
`Each bit in the data word includes a burst of 32 cycles
`with a repetition rate of 36 kHz. The equivalent times
`are shown in the pulse diagrams.
`The most suitable Vishay IR receivers for receiving
`the RC5 Code are: TSOP1236, TSOP2236,
`TSOP4836 and TSOP6236.
`
`The data word
`is repeated as
`long as a key is
`pressed.
`
`Example
`of a data word
`
`Burst
`(half bit)
`
`114ms
`
`Da ta
`
`24.9ms
`
`Bit length 1.78ms
`
`6 data
`
`bit
`
`27.8μs
`
`5 a
`
`ddress
`bit
`
`1 t
`
`oggle
`bit
`
`2 start
`bit
`
`17052
`
`868μs (32 cycles of 36kHz)
`
`Figure 4. RC 5 transmission code
`
`Document Number: 80071
`Rev. A2, 27-Aug-03
`
`www.vishay.com
`2
`
`

`

`Vishay Semiconductors
`
`The NEC Code:
`The NEC code also works with bursts of a defined
`carrier frequency, which is 38 kHz. All Vishay receiver
`modules operate well with this system.
`The NEC code starts the transmission using a so-
`called leader code, a burst of a length of 9 ms, fol-
`lowed by the data word after a pause of 4.5 ms. The
`initial idea of this leader code is to settle the internal
`control loops in the receiver modules. But for the
`Vishay receiver such a preburst is not necessary.
`As long as a key is pressed, only the leader code is
`repeatedly transmitted, followed by a single bit. A
`specialty of this code is the property of constant word
`length in connection with pulse distance modulation.
`Both address and command bits are transmitted
`twice, first as the normal byte followed by the inverted
`''Leader code''
`
`Data word
`
`VISHAY
`
`byte. This is shown in Figure 5. The burst defining a
`bit contains 22 pulses each of a length of 8.77 μs with
`a period of 26.3 μs. A ’’0’’ is represented by a pulse
`distance of 1.125 ms, the ’’1’’ with 2.25 ms, respec-
`tively. 8 address bits are used to identify the device to
`be controlled. A further 8 bits are used for the trans-
`mission of the command. As mentioned above, the
`words are always followed, without a pause, by the
`inverted words, e.g. the transmission of the address
`’’00110111’’ and the command ’’0001101’’ is per-
`formed
`by
`sending
`the
`word:
`’’00110111'11001000'00011010'11100101’’.
`A special version of the NEC code is with repetitive
`data. That means that each 108 ms the preburst
`including all the data is repeated as long as the key is
`pressed.
`
`.
`
`67.5 ms
`108 ms
`
`108 ms
`
`4.5
`9 ms
`ms
`13.5 ms
`
`Address code Address code
`8 bit
`8 bit
`
`Data code
`8 bit
`
`Data code
`8 bit
`
`27 ms
`
`27 ms
`
`17053
`
`Figure 5. NEC transmission code
`
`www.vishay.com
`3
`
`Document Number: 80071
`Rev. A2, 27-Aug-03
`
`

`

`VISHAY
`
`Vishay Semiconductors
`
`Data transmission with the
`TSOP Receiver Modules:
`Although the TSOP receiver modules are mainly used
`for IR remote control, some of them can be used for
`continuous data transmission as well. For this pur-
`pose we
`recommend either
`the TSOP11xx,
`
`TSOP21xx, TSOP41xx, TSOP61xx series (data rate
`below 4 kbit/s) or the TSOP7000 and TSOP5700
`(data rate up to 20 kbit/s). These receivers are suit-
`able for continuous transmission and short bursts.
`Two examples for such a continuous data transmis-
`sion are shown in Figure 6 and 7:
`
`.
`
`Start
`
`''1''
`
`''0''
`
`''0''
`
`''1''
`
`''0''
`
`''1''
`
`''1''
`
`''0''
`
`Stop
`
`One Byte in RS 232
`2400 bps
`
`17054
`
`17055
`
`150 μs (6 cycles at 40 kHz)
`
`Figure 6. Example of a Data transmission at 2400 bps with TSOP4140
`
`.
`
`107 μ s (6 cycles at 56 kHz)
`
`286 μ s = ''00'' 357 μs = ''01''
`
`500 μs = ''11 ''
`
`357 μs = ''01''
`
`429 μs = ''10''
`
`Figure 7. Example of a data transmission at about 4000 bps with the TSOP1156
`
`Compatibility of the TSOP Receiver
`Modules with Data Formats
`Vishay can offer a variety of different IR receiver
`series in order to be able to supply the optimized solu-
`tion for each application. Help in selecting the right
`part with respect to each data format is given here.
`In case of an application for data transmission with a
`data rate above 4 kbit/s or in case of a carrier fre-
`quency of 455 kHz the selection is TSOP7000 or
`TSOP5700.
`
`2.
`
`If the application is a normal IR remote control appli-
`cation (30 kHz to 56 kHz) or if it is operating at a lower
`data rate, then the customer has the choice among 3
`categories of IR receivers:
`1.
`For short bursts or continuous data transmis-
`sion (e.g. TSOP11xx or TSOP21xx),
`For standard remote control applications (e.g.
`TSOP12xx or TSOP48xx),
`For operation under extreme disturbance con-
`ditions (e.g.TSOP24xx or TSOP44xx).
`In table 2 and table 3 there is an overview which IR
`receiver type can be used for what kind of data for-
`mat.
`
`3.
`
`Document Number: 80071
`Rev. A2, 27-Aug-03
`
`www.vishay.com
`4
`
`

`

`Vishay Semiconductors
`
`VISHAY
`
`TSOP11xx
`TSOP21xx
`TSOP321xx
`TSOP41xx
`TSOP341xx
`TSOP61xx
`TSOP361xx
`6 cycles
`
`TSOP12xx
`TSOP22xx
`TSOP322xx
`TSOP48xx
`TSOP348xx
`TSOP62xx
`TSOP362xx
`10 cycles
`
`10 cycles
`
`14 cycles
`
`TSOP24xx
`TSOP324xx
`TSOP44xx
`TSOP344xx
`
`TSOP7000
`TSOP5700
`
`10 cycles
`
`14 cycles
`
`10 cycles (22μs)
`
`12 cycles (26μs)
`
`2200 bursts/sec.
`
` 800 bursts/sec.
`
` 400 bursts/sec.
`
` 20000 bursts/sec.
`
`Table 2: Data Signal Limitations for the Vishay IR Receiver Modules
`
`Minimum Burst Length
`(number of cycles of carrier)
`Minimum Gap Time between the
`bursts (carrier cycles)
`Maximum rate of data bursts
`
`The following table gives some examples of possible
`data formats:
`
`TSOP12xx
`TSOP11xx
`TSOP22xx
`TSOP21xx
`TSOP322xx
`TSOP321xx
`TSOP48xx
`TSOP41xx
`TSOP348xx
`TSOP341xx
`TSOP62xx
`TSOP61xx
`TSOP362xx
`TSOP361xx
`+
`+
`NEC Code (repetitive pulse)
`+
`+
`NEC Code (repetitive data)
`+
`+
`RC5 Code
`+
`+
`RC6 Code, Mode 0
`+
`+
`RC6 Code, Mode 1A
`+
`+
`RC6 Code, Mode 1B (bi directional)
`+
`+
`RC6 Code, Mode 2A
`-
`+
`RCMM Code
`o
`+
`RECS-80 Code
`+
`+
`R-2000 Code (33 kHz)
`+
`+
`Thomson RCA Code (56.7 kHz)
`+
`+
`Toshiba Micom Format (similar NEC)
`+
`+
`Grundig Code (30.3 kHz or 36 kHz)
`+
`+
`Sony 12 Bit Code
`+
`+
`Sony 15 Bit Code
`+
`+
`Sony 20 Bit Code
`+
`+
`Sharp Code
`+
`+
`Kaseikyo Matsushita Code (36.7 kHz)
`+
`+
`Mitsubishi Code (33 kHz, 16 bit)
`+
`+
`Mitsubishi Code (38 kHz, preburst 8 ms, 16 bit)
`+
`+
`Zenith Trackball Code (40 kHz)
`-
`+
`Continuous transmission 4000 bps
`+
`+
`Continuous transmission 1000 bps
`+: data format is suitable; o: data format is received with lower sensitivity -: not recommended
`
`Table 3: Suitable TSOP Types for standard transmission codes
`
`TSOP24xx
`TSOP324xx
`TSOP44xx
`TSOP344xx
`
`+
`-
`+
`+
`+
`-
`-
`-
`o
`+
`-
`+
`+
`-
`-
`-
`+
`-
`+
`-
`o
`-
`-
`
`www.vishay.com
`5
`
`Document Number: 80071
`Rev. A2, 27-Aug-03
`
`