457 lines
10 KiB
ReStructuredText
457 lines
10 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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..
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.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
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.. _Remote_controllers_Protocols:
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*****************************************
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Remote Controller Protocols and Scancodes
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*****************************************
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IR is encoded as a series of pulses and spaces, using a protocol. These
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protocols can encode e.g. an address (which device should respond) and a
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command: what it should do. The values for these are not always consistent
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across different devices for a given protocol.
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Therefore out the output of the IR decoder is a scancode; a single u32
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value. Using keymap tables this can be mapped to linux key codes.
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Other things can be encoded too. Some IR protocols encode a toggle bit; this
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is to distinguish whether the same button is being held down, or has been
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released and pressed again. If has been released and pressed again, the
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toggle bit will invert from one IR message to the next.
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Some remotes have a pointer-type device which can used to control the
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mouse; some air conditioning systems can have their target temperature
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target set in IR.
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The following are the protocols the kernel knows about and also lists
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how scancodes are encoded for each protocol.
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rc-5 (RC_PROTO_RC5)
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-------------------
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This IR protocol uses manchester encoding to encode 14 bits. There is a
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detailed description here https://www.sbprojects.net/knowledge/ir/rc5.php.
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The scancode encoding is *not* consistent with the lirc daemon (lircd) rc5
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protocol, or the manchester BPF decoder.
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.. flat-table:: rc5 bits scancode mapping
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:widths: 1 1 2
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* - rc-5 bit
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- scancode bit
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- description
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* - 1
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- none
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- Start bit, always set
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* - 1
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- 6 (inverted)
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- 2nd start bit in rc5, re-used as 6th command bit
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* - 1
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- none
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- Toggle bit
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* - 5
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- 8 to 13
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- Address
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* - 6
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- 0 to 5
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- Command
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There is a variant of rc5 called either rc5x or extended rc5
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where there the second stop bit is the 6th commmand bit, but inverted.
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This is done so it the scancodes and encoding is compatible with existing
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schemes. This bit is stored in bit 6 of the scancode, inverted. This is
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done to keep it compatible with plain rc-5 where there are two start bits.
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rc-5-sz (RC_PROTO_RC5_SZ)
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-------------------------
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This is much like rc-5 but one bit longer. The scancode is encoded
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differently.
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.. flat-table:: rc-5-sz bits scancode mapping
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:widths: 1 1 2
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* - rc-5-sz bits
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- scancode bit
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- description
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* - 1
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- none
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- Start bit, always set
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* - 1
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- 13
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- Address bit
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* - 1
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- none
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- Toggle bit
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* - 6
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- 6 to 11
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- Address
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* - 6
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- 0 to 5
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- Command
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rc-5x-20 (RC_PROTO_RC5X_20)
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---------------------------
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This rc-5 extended to encoded 20 bits. The is a 3555 microseconds space
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after the 8th bit.
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.. flat-table:: rc-5x-20 bits scancode mapping
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:widths: 1 1 2
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* - rc-5-sz bits
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- scancode bit
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- description
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* - 1
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- none
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- Start bit, always set
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* - 1
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- 14
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- Address bit
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* - 1
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- none
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- Toggle bit
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* - 5
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- 16 to 20
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- Address
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* - 6
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- 8 to 13
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- Address
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* - 6
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- 0 to 5
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- Command
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jvc (RC_PROTO_JVC)
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------------------
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The jvc protocol is much like nec, without the inverted values. It is
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described here https://www.sbprojects.net/knowledge/ir/jvc.php.
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The scancode is a 16 bits value, where the address is the lower 8 bits
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and the command the higher 8 bits; this is reversed from IR order.
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sony-12 (RC_PROTO_SONY12)
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-------------------------
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The sony protocol is a pulse-width encoding. There are three variants,
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which just differ in number of bits and scancode encoding.
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.. flat-table:: sony-12 bits scancode mapping
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:widths: 1 1 2
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* - sony-12 bits
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- scancode bit
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- description
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* - 5
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- 16 to 20
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- device
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* - 7
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- 0 to 6
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- function
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sony-15 (RC_PROTO_SONY15)
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-------------------------
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The sony protocol is a pulse-width encoding. There are three variants,
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which just differ in number of bits and scancode encoding.
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.. flat-table:: sony-12 bits scancode mapping
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:widths: 1 1 2
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* - sony-12 bits
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- scancode bit
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- description
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* - 8
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- 16 to 23
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- device
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* - 7
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- 0 to 6
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- function
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sony-20 (RC_PROTO_SONY20)
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-------------------------
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The sony protocol is a pulse-width encoding. There are three variants,
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which just differ in number of bits and scancode encoding.
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.. flat-table:: sony-20 bits scancode mapping
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:widths: 1 1 2
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* - sony-20 bits
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- scancode bit
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- description
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* - 5
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- 16 to 20
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- device
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* - 7
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- 0 to 7
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- device
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* - 8
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- 8 to 15
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- extended bits
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nec (RC_PROTO_NEC)
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------------------
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The nec protocol encodes an 8 bit address and an 8 bit command. It is
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described here https://www.sbprojects.net/knowledge/ir/nec.php. Note
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that the protocol sends least significant bit first.
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As a check, the nec protocol sends the address and command twice; the
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second time it is inverted. This is done for verification.
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A plain nec IR message has 16 bits; the high 8 bits are the address
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and the low 8 bits are the command.
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nec-x (RC_PROTO_NECX)
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---------------------
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Extended nec has a 16 bit address and a 8 bit command. This is encoded
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as a 24 bit value as you would expect, with the lower 8 bits the command
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and the upper 16 bits the address.
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nec-32 (RC_PROTO_NEC32)
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-----------------------
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nec-32 does not send an inverted address or an inverted command; the
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entire message, all 32 bits, are used.
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For this to be decoded correctly, the second 8 bits must not be the
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inverted value of the first, and also the last 8 bits must not be the
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inverted value of the third 8 bit value.
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The scancode has a somewhat unusual encoding.
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.. flat-table:: nec-32 bits scancode mapping
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* - nec-32 bits
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- scancode bit
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* - First 8 bits
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- 16 to 23
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* - Second 8 bits
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- 24 to 31
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* - Third 8 bits
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- 0 to 7
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* - Fourth 8 bits
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- 8 to 15
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sanyo (RC_PROTO_SANYO)
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----------------------
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The sanyo protocol is like the nec protocol, but with 13 bits address
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rather than 8 bits. Both the address and the command are followed by
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their inverted versions, but these are not present in the scancodes.
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Bis 8 to 20 of the scancode is the 13 bits address, and the lower 8
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bits are the command.
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mcir2-kbd (RC_PROTO_MCIR2_KBD)
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------------------------------
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This protocol is generated by the Microsoft MCE keyboard for keyboard
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events. Refer to the ir-mce_kbd-decoder.c to see how it is encoded.
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mcir2-mse (RC_PROTO_MCIR2_MSE)
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------------------------------
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This protocol is generated by the Microsoft MCE keyboard for pointer
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events. Refer to the ir-mce_kbd-decoder.c to see how it is encoded.
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rc-6-0 (RC_PROTO_RC6_0)
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-----------------------
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This is the rc-6 in mode 0. rc-6 is described here
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https://www.sbprojects.net/knowledge/ir/rc6.php.
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The scancode is the exact 16 bits as in the protocol. There is also a
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toggle bit.
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rc-6-6a-20 (RC_PROTO_RC6_6A_20)
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-------------------------------
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This is the rc-6 in mode 6a, 20 bits. rc-6 is described here
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https://www.sbprojects.net/knowledge/ir/rc6.php.
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The scancode is the exact 20 bits
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as in the protocol. There is also a toggle bit.
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rc-6-6a-24 (RC_PROTO_RC6_6A_24)
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-------------------------------
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This is the rc-6 in mode 6a, 24 bits. rc-6 is described here
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https://www.sbprojects.net/knowledge/ir/rc6.php.
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The scancode is the exact 24 bits
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as in the protocol. There is also a toggle bit.
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rc-6-6a-32 (RC_PROTO_RC6_6A_32)
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-------------------------------
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This is the rc-6 in mode 6a, 32 bits. rc-6 is described here
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https://www.sbprojects.net/knowledge/ir/rc6.php.
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The upper 16 bits are the vendor,
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and the lower 16 bits are the vendor-specific bits. This protocol is
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for the non-Microsoft MCE variant (vendor != 0x800f).
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rc-6-mce (RC_PROTO_RC6_MCE)
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---------------------------
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This is the rc-6 in mode 6a, 32 bits. The upper 16 bits are the vendor,
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and the lower 16 bits are the vendor-specific bits. This protocol is
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for the Microsoft MCE variant (vendor = 0x800f). The toggle bit in the
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protocol itself is ignored, and the 16th bit should be takes as the toggle
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bit.
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sharp (RC_PROTO_SHARP)
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----------------------
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This is a protocol used by Sharp VCRs, is described here
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https://www.sbprojects.net/knowledge/ir/sharp.php. There is a very long
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(40ms) space between the normal and inverted values, and some IR receivers
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cannot decode this.
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There is a 5 bit address and a 8 bit command. In the scancode the address is
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in bits 8 to 12, and the command in bits 0 to 7.
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xmp (RC_PROTO_XMP)
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------------------
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This protocol has several versions and only version 1 is supported. Refer
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to the decoder (ir-xmp-decoder.c) to see how it is encoded.
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cec (RC_PROTO_CEC)
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------------------
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This is not an IR protocol, this is a protocol over CEC. The CEC
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infrastructure uses rc-core for handling CEC commands, so that they
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can easily be remapped.
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imon (RC_PROTO_IMON)
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--------------------
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This protocol is used by Antec Veris/SoundGraph iMON remotes.
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The protocol
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describes both button presses and pointer movements. The protocol encodes
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31 bits, and the scancode is simply the 31 bits with the top bit always 0.
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rc-mm-12 (RC_PROTO_RCMM12)
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--------------------------
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The rc-mm protocol is described here
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https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply
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the 12 bits.
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rc-mm-24 (RC_PROTO_RCMM24)
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--------------------------
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The rc-mm protocol is described here
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https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply
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the 24 bits.
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rc-mm-32 (RC_PROTO_RCMM32)
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--------------------------
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The rc-mm protocol is described here
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https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply
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the 32 bits.
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xbox-dvd (RC_PROTO_XBOX_DVD)
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----------------------------
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This protocol is used by XBox DVD Remote, which was made for the original
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XBox. There is no in-kernel decoder or encoder for this protocol. The usb
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device decodes the protocol. There is a BPF decoder available in v4l-utils.
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