rc-protos.rst (10198B)
1.. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later 2 3.. _Remote_controllers_Protocols: 4 5***************************************** 6Remote Controller Protocols and Scancodes 7***************************************** 8 9IR is encoded as a series of pulses and spaces, using a protocol. These 10protocols can encode e.g. an address (which device should respond) and a 11command: what it should do. The values for these are not always consistent 12across different devices for a given protocol. 13 14Therefore out the output of the IR decoder is a scancode; a single u32 15value. Using keymap tables this can be mapped to linux key codes. 16 17Other things can be encoded too. Some IR protocols encode a toggle bit; this 18is to distinguish whether the same button is being held down, or has been 19released and pressed again. If has been released and pressed again, the 20toggle bit will invert from one IR message to the next. 21 22Some remotes have a pointer-type device which can used to control the 23mouse; some air conditioning systems can have their target temperature 24target set in IR. 25 26The following are the protocols the kernel knows about and also lists 27how scancodes are encoded for each protocol. 28 29rc-5 (RC_PROTO_RC5) 30------------------- 31 32This IR protocol uses manchester encoding to encode 14 bits. There is a 33detailed description here https://www.sbprojects.net/knowledge/ir/rc5.php. 34 35The scancode encoding is *not* consistent with the lirc daemon (lircd) rc5 36protocol, or the manchester BPF decoder. 37 38.. flat-table:: rc5 bits scancode mapping 39 :widths: 1 1 2 40 41 * - rc-5 bit 42 43 - scancode bit 44 45 - description 46 47 * - 1 48 49 - none 50 51 - Start bit, always set 52 53 * - 1 54 55 - 6 (inverted) 56 57 - 2nd start bit in rc5, re-used as 6th command bit 58 59 * - 1 60 61 - none 62 63 - Toggle bit 64 65 * - 5 66 67 - 8 to 13 68 69 - Address 70 71 * - 6 72 73 - 0 to 5 74 75 - Command 76 77There is a variant of rc5 called either rc5x or extended rc5 78where there the second stop bit is the 6th commmand bit, but inverted. 79This is done so it the scancodes and encoding is compatible with existing 80schemes. This bit is stored in bit 6 of the scancode, inverted. This is 81done to keep it compatible with plain rc-5 where there are two start bits. 82 83rc-5-sz (RC_PROTO_RC5_SZ) 84------------------------- 85This is much like rc-5 but one bit longer. The scancode is encoded 86differently. 87 88.. flat-table:: rc-5-sz bits scancode mapping 89 :widths: 1 1 2 90 91 * - rc-5-sz bits 92 93 - scancode bit 94 95 - description 96 97 * - 1 98 99 - none 100 101 - Start bit, always set 102 103 * - 1 104 105 - 13 106 107 - Address bit 108 109 * - 1 110 111 - none 112 113 - Toggle bit 114 115 * - 6 116 117 - 6 to 11 118 119 - Address 120 121 * - 6 122 123 - 0 to 5 124 125 - Command 126 127rc-5x-20 (RC_PROTO_RC5X_20) 128--------------------------- 129 130This rc-5 extended to encoded 20 bits. The is a 3555 microseconds space 131after the 8th bit. 132 133.. flat-table:: rc-5x-20 bits scancode mapping 134 :widths: 1 1 2 135 136 * - rc-5-sz bits 137 138 - scancode bit 139 140 - description 141 142 * - 1 143 144 - none 145 146 - Start bit, always set 147 148 * - 1 149 150 - 14 151 152 - Address bit 153 154 * - 1 155 156 - none 157 158 - Toggle bit 159 160 * - 5 161 162 - 16 to 20 163 164 - Address 165 166 * - 6 167 168 - 8 to 13 169 170 - Address 171 172 * - 6 173 174 - 0 to 5 175 176 - Command 177 178 179jvc (RC_PROTO_JVC) 180------------------ 181 182The jvc protocol is much like nec, without the inverted values. It is 183described here https://www.sbprojects.net/knowledge/ir/jvc.php. 184 185The scancode is a 16 bits value, where the address is the lower 8 bits 186and the command the higher 8 bits; this is reversed from IR order. 187 188sony-12 (RC_PROTO_SONY12) 189------------------------- 190 191The sony protocol is a pulse-width encoding. There are three variants, 192which just differ in number of bits and scancode encoding. 193 194.. flat-table:: sony-12 bits scancode mapping 195 :widths: 1 1 2 196 197 * - sony-12 bits 198 199 - scancode bit 200 201 - description 202 203 * - 5 204 205 - 16 to 20 206 207 - device 208 209 * - 7 210 211 - 0 to 6 212 213 - function 214 215sony-15 (RC_PROTO_SONY15) 216------------------------- 217 218The sony protocol is a pulse-width encoding. There are three variants, 219which just differ in number of bits and scancode encoding. 220 221.. flat-table:: sony-12 bits scancode mapping 222 :widths: 1 1 2 223 224 * - sony-12 bits 225 226 - scancode bit 227 228 - description 229 230 * - 8 231 232 - 16 to 23 233 234 - device 235 236 * - 7 237 238 - 0 to 6 239 240 - function 241 242sony-20 (RC_PROTO_SONY20) 243------------------------- 244 245The sony protocol is a pulse-width encoding. There are three variants, 246which just differ in number of bits and scancode encoding. 247 248.. flat-table:: sony-20 bits scancode mapping 249 :widths: 1 1 2 250 251 * - sony-20 bits 252 253 - scancode bit 254 255 - description 256 257 * - 5 258 259 - 16 to 20 260 261 - device 262 263 * - 7 264 265 - 0 to 7 266 267 - device 268 269 * - 8 270 271 - 8 to 15 272 273 - extended bits 274 275nec (RC_PROTO_NEC) 276------------------ 277 278The nec protocol encodes an 8 bit address and an 8 bit command. It is 279described here https://www.sbprojects.net/knowledge/ir/nec.php. Note 280that the protocol sends least significant bit first. 281 282As a check, the nec protocol sends the address and command twice; the 283second time it is inverted. This is done for verification. 284 285A plain nec IR message has 16 bits; the high 8 bits are the address 286and the low 8 bits are the command. 287 288nec-x (RC_PROTO_NECX) 289--------------------- 290 291Extended nec has a 16 bit address and a 8 bit command. This is encoded 292as a 24 bit value as you would expect, with the lower 8 bits the command 293and the upper 16 bits the address. 294 295nec-32 (RC_PROTO_NEC32) 296----------------------- 297 298nec-32 does not send an inverted address or an inverted command; the 299entire message, all 32 bits, are used. 300 301For this to be decoded correctly, the second 8 bits must not be the 302inverted value of the first, and also the last 8 bits must not be the 303inverted value of the third 8 bit value. 304 305The scancode has a somewhat unusual encoding. 306 307.. flat-table:: nec-32 bits scancode mapping 308 309 * - nec-32 bits 310 311 - scancode bit 312 313 * - First 8 bits 314 315 - 16 to 23 316 317 * - Second 8 bits 318 319 - 24 to 31 320 321 * - Third 8 bits 322 323 - 0 to 7 324 325 * - Fourth 8 bits 326 327 - 8 to 15 328 329sanyo (RC_PROTO_SANYO) 330---------------------- 331 332The sanyo protocol is like the nec protocol, but with 13 bits address 333rather than 8 bits. Both the address and the command are followed by 334their inverted versions, but these are not present in the scancodes. 335 336Bis 8 to 20 of the scancode is the 13 bits address, and the lower 8 337bits are the command. 338 339mcir2-kbd (RC_PROTO_MCIR2_KBD) 340------------------------------ 341 342This protocol is generated by the Microsoft MCE keyboard for keyboard 343events. Refer to the ir-mce_kbd-decoder.c to see how it is encoded. 344 345mcir2-mse (RC_PROTO_MCIR2_MSE) 346------------------------------ 347 348This protocol is generated by the Microsoft MCE keyboard for pointer 349events. Refer to the ir-mce_kbd-decoder.c to see how it is encoded. 350 351rc-6-0 (RC_PROTO_RC6_0) 352----------------------- 353 354This is the rc-6 in mode 0. rc-6 is described here 355https://www.sbprojects.net/knowledge/ir/rc6.php. 356The scancode is the exact 16 bits as in the protocol. There is also a 357toggle bit. 358 359rc-6-6a-20 (RC_PROTO_RC6_6A_20) 360------------------------------- 361 362This is the rc-6 in mode 6a, 20 bits. rc-6 is described here 363https://www.sbprojects.net/knowledge/ir/rc6.php. 364The scancode is the exact 20 bits 365as in the protocol. There is also a toggle bit. 366 367rc-6-6a-24 (RC_PROTO_RC6_6A_24) 368------------------------------- 369 370This is the rc-6 in mode 6a, 24 bits. rc-6 is described here 371https://www.sbprojects.net/knowledge/ir/rc6.php. 372The scancode is the exact 24 bits 373as in the protocol. There is also a toggle bit. 374 375rc-6-6a-32 (RC_PROTO_RC6_6A_32) 376------------------------------- 377 378This is the rc-6 in mode 6a, 32 bits. rc-6 is described here 379https://www.sbprojects.net/knowledge/ir/rc6.php. 380The upper 16 bits are the vendor, 381and the lower 16 bits are the vendor-specific bits. This protocol is 382for the non-Microsoft MCE variant (vendor != 0x800f). 383 384 385rc-6-mce (RC_PROTO_RC6_MCE) 386--------------------------- 387 388This is the rc-6 in mode 6a, 32 bits. The upper 16 bits are the vendor, 389and the lower 16 bits are the vendor-specific bits. This protocol is 390for the Microsoft MCE variant (vendor = 0x800f). The toggle bit in the 391protocol itself is ignored, and the 16th bit should be takes as the toggle 392bit. 393 394sharp (RC_PROTO_SHARP) 395---------------------- 396 397This is a protocol used by Sharp VCRs, is described here 398https://www.sbprojects.net/knowledge/ir/sharp.php. There is a very long 399(40ms) space between the normal and inverted values, and some IR receivers 400cannot decode this. 401 402There is a 5 bit address and a 8 bit command. In the scancode the address is 403in bits 8 to 12, and the command in bits 0 to 7. 404 405xmp (RC_PROTO_XMP) 406------------------ 407 408This protocol has several versions and only version 1 is supported. Refer 409to the decoder (ir-xmp-decoder.c) to see how it is encoded. 410 411 412cec (RC_PROTO_CEC) 413------------------ 414 415This is not an IR protocol, this is a protocol over CEC. The CEC 416infrastructure uses rc-core for handling CEC commands, so that they 417can easily be remapped. 418 419imon (RC_PROTO_IMON) 420-------------------- 421 422This protocol is used by Antec Veris/SoundGraph iMON remotes. 423 424The protocol 425describes both button presses and pointer movements. The protocol encodes 42631 bits, and the scancode is simply the 31 bits with the top bit always 0. 427 428rc-mm-12 (RC_PROTO_RCMM12) 429-------------------------- 430 431The rc-mm protocol is described here 432https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply 433the 12 bits. 434 435rc-mm-24 (RC_PROTO_RCMM24) 436-------------------------- 437 438The rc-mm protocol is described here 439https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply 440the 24 bits. 441 442rc-mm-32 (RC_PROTO_RCMM32) 443-------------------------- 444 445The rc-mm protocol is described here 446https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply 447the 32 bits. 448 449xbox-dvd (RC_PROTO_XBOX_DVD) 450---------------------------- 451 452This protocol is used by XBox DVD Remote, which was made for the original 453XBox. There is no in-kernel decoder or encoder for this protocol. The usb 454device decodes the protocol. There is a BPF decoder available in v4l-utils.