1 .. SPDX-License-Identifier: GPL-2.0 OR GFDL-1.1-no-invariants-or-later 2 3 .. _Remote_controllers_Protocols: 4 5 ***************************************** 6 Remote Controller Protocols and Scancodes 7 ***************************************** 8 9 IR is encoded as a series of pulses and spaces, using a protocol. These 10 protocols can encode e.g. an address (which device should respond) and a 11 command: what it should do. The values for these are not always consistent 12 across different devices for a given protocol. 13 14 Therefore out the output of the IR decoder is a scancode; a single u32 15 value. Using keymap tables this can be mapped to linux key codes. 16 17 Other things can be encoded too. Some IR protocols encode a toggle bit; this 18 is to distinguish whether the same button is being held down, or has been 19 released and pressed again. If has been released and pressed again, the 20 toggle bit will invert from one IR message to the next. 21 22 Some remotes have a pointer-type device which can used to control the 23 mouse; some air conditioning systems can have their target temperature 24 target set in IR. 25 26 The following are the protocols the kernel knows about and also lists 27 how scancodes are encoded for each protocol. 28 29 rc-5 (RC_PROTO_RC5) 30 ------------------- 31 32 This IR protocol uses manchester encoding to encode 14 bits. There is a 33 detailed description here https://www.sbprojects.net/knowledge/ir/rc5.php. 34 35 The scancode encoding is *not* consistent with the lirc daemon (lircd) rc5 36 protocol, 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 77 There is a variant of rc5 called either rc5x or extended rc5 78 where there the second stop bit is the 6th command bit, but inverted. 79 This is done so it the scancodes and encoding is compatible with existing 80 schemes. This bit is stored in bit 6 of the scancode, inverted. This is 81 done to keep it compatible with plain rc-5 where there are two start bits. 82 83 rc-5-sz (RC_PROTO_RC5_SZ) 84 ------------------------- 85 This is much like rc-5 but one bit longer. The scancode is encoded 86 differently. 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 126 127 rc-5x-20 (RC_PROTO_RC5X_20) 128 --------------------------- 129 130 This rc-5 extended to encoded 20 bits. The is a 3555 microseconds space 131 after 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 177 178 179 jvc (RC_PROTO_JVC) 180 ------------------ 181 182 The jvc protocol is much like nec, without the inverted values. It is 183 described here https://www.sbprojects.net/knowledge/ir/jvc.php. 184 185 The scancode is a 16 bits value, where the address is the lower 8 bits 186 and the command the higher 8 bits; this is reversed from IR order. 187 188 sony-12 (RC_PROTO_SONY12) 189 ------------------------- 190 191 The sony protocol is a pulse-width encoding. There are three variants, 192 which 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 214 215 sony-15 (RC_PROTO_SONY15) 216 ------------------------- 217 218 The sony protocol is a pulse-width encoding. There are three variants, 219 which 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 241 242 sony-20 (RC_PROTO_SONY20) 243 ------------------------- 244 245 The sony protocol is a pulse-width encoding. There are three variants, 246 which 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 274 275 nec (RC_PROTO_NEC) 276 ------------------ 277 278 The nec protocol encodes an 8 bit address and an 8 bit command. It is 279 described here https://www.sbprojects.net/knowledge/ir/nec.php. Note 280 that the protocol sends least significant bit first. 281 282 As a check, the nec protocol sends the address and command twice; the 283 second time it is inverted. This is done for verification. 284 285 A plain nec IR message has 16 bits; the high 8 bits are the address 286 and the low 8 bits are the command. 287 288 nec-x (RC_PROTO_NECX) 289 --------------------- 290 291 Extended nec has a 16 bit address and a 8 bit command. This is encoded 292 as a 24 bit value as you would expect, with the lower 8 bits the command 293 and the upper 16 bits the address. 294 295 nec-32 (RC_PROTO_NEC32) 296 ----------------------- 297 298 nec-32 does not send an inverted address or an inverted command; the 299 entire message, all 32 bits, are used. 300 301 For this to be decoded correctly, the second 8 bits must not be the 302 inverted value of the first, and also the last 8 bits must not be the 303 inverted value of the third 8 bit value. 304 305 The 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 15 328 329 sanyo (RC_PROTO_SANYO) 330 ---------------------- 331 332 The sanyo protocol is like the nec protocol, but with 13 bits address 333 rather than 8 bits. Both the address and the command are followed by 334 their inverted versions, but these are not present in the scancodes. 335 336 Bis 8 to 20 of the scancode is the 13 bits address, and the lower 8 337 bits are the command. 338 339 mcir2-kbd (RC_PROTO_MCIR2_KBD) 340 ------------------------------ 341 342 This protocol is generated by the Microsoft MCE keyboard for keyboard 343 events. Refer to the ir-mce_kbd-decoder.c to see how it is encoded. 344 345 mcir2-mse (RC_PROTO_MCIR2_MSE) 346 ------------------------------ 347 348 This protocol is generated by the Microsoft MCE keyboard for pointer 349 events. Refer to the ir-mce_kbd-decoder.c to see how it is encoded. 350 351 rc-6-0 (RC_PROTO_RC6_0) 352 ----------------------- 353 354 This is the rc-6 in mode 0. rc-6 is described here 355 https://www.sbprojects.net/knowledge/ir/rc6.php. 356 The scancode is the exact 16 bits as in the protocol. There is also a 357 toggle bit. 358 359 rc-6-6a-20 (RC_PROTO_RC6_6A_20) 360 ------------------------------- 361 362 This is the rc-6 in mode 6a, 20 bits. rc-6 is described here 363 https://www.sbprojects.net/knowledge/ir/rc6.php. 364 The scancode is the exact 20 bits 365 as in the protocol. There is also a toggle bit. 366 367 rc-6-6a-24 (RC_PROTO_RC6_6A_24) 368 ------------------------------- 369 370 This is the rc-6 in mode 6a, 24 bits. rc-6 is described here 371 https://www.sbprojects.net/knowledge/ir/rc6.php. 372 The scancode is the exact 24 bits 373 as in the protocol. There is also a toggle bit. 374 375 rc-6-6a-32 (RC_PROTO_RC6_6A_32) 376 ------------------------------- 377 378 This is the rc-6 in mode 6a, 32 bits. rc-6 is described here 379 https://www.sbprojects.net/knowledge/ir/rc6.php. 380 The upper 16 bits are the vendor, 381 and the lower 16 bits are the vendor-specific bits. This protocol is 382 for the non-Microsoft MCE variant (vendor != 0x800f). 383 384 385 rc-6-mce (RC_PROTO_RC6_MCE) 386 --------------------------- 387 388 This is the rc-6 in mode 6a, 32 bits. The upper 16 bits are the vendor, 389 and the lower 16 bits are the vendor-specific bits. This protocol is 390 for the Microsoft MCE variant (vendor = 0x800f). The toggle bit in the 391 protocol itself is ignored, and the 16th bit should be takes as the toggle 392 bit. 393 394 sharp (RC_PROTO_SHARP) 395 ---------------------- 396 397 This is a protocol used by Sharp VCRs, is described here 398 https://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 400 cannot decode this. 401 402 There is a 5 bit address and a 8 bit command. In the scancode the address is 403 in bits 8 to 12, and the command in bits 0 to 7. 404 405 xmp (RC_PROTO_XMP) 406 ------------------ 407 408 This protocol has several versions and only version 1 is supported. Refer 409 to the decoder (ir-xmp-decoder.c) to see how it is encoded. 410 411 412 cec (RC_PROTO_CEC) 413 ------------------ 414 415 This is not an IR protocol, this is a protocol over CEC. The CEC 416 infrastructure uses rc-core for handling CEC commands, so that they 417 can easily be remapped. 418 419 imon (RC_PROTO_IMON) 420 -------------------- 421 422 This protocol is used by Antec Veris/SoundGraph iMON remotes. 423 424 The protocol 425 describes both button presses and pointer movements. The protocol encodes 426 31 bits, and the scancode is simply the 31 bits with the top bit always 0. 427 428 rc-mm-12 (RC_PROTO_RCMM12) 429 -------------------------- 430 431 The rc-mm protocol is described here 432 https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply 433 the 12 bits. 434 435 rc-mm-24 (RC_PROTO_RCMM24) 436 -------------------------- 437 438 The rc-mm protocol is described here 439 https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply 440 the 24 bits. 441 442 rc-mm-32 (RC_PROTO_RCMM32) 443 -------------------------- 444 445 The rc-mm protocol is described here 446 https://www.sbprojects.net/knowledge/ir/rcmm.php. The scancode is simply 447 the 32 bits. 448 449 xbox-dvd (RC_PROTO_XBOX_DVD) 450 ---------------------------- 451 452 This protocol is used by XBox DVD Remote, which was made for the original 453 XBox. There is no in-kernel decoder or encoder for this protocol. The usb 454 device decodes the protocol. There is a BPF decoder available in v4l-utils.
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