Documentation/input/elantech.txt

   1 Elantech Touchpad Driver
   2 ========================
   3
   4         Copyright (C) 2007-2008 Arjan Opmeer <arjan@opmeer.net>
   5
   6         Extra information for hardware version 1 found and
   7         provided by Steve Havelka
   8
   9         Version 2 (EeePC) hardware support based on patches
  10         received from Woody at Xandros and forwarded to me
  11         by user StewieGriffin at the eeeuser.com forum
  12
  13
  14 Contents
  15 ~~~~~~~~
  16
  17  1. Introduction
  18  2. Extra knobs
  19  3. Differentiating hardware versions
  20  4. Hardware version 1
  21     4.1 Registers
  22     4.2 Native relative mode 4 byte packet format
  23     4.3 Native absolute mode 4 byte packet format
  24  5. Hardware version 2
  25     5.1 Registers
  26     5.2 Native absolute mode 6 byte packet format
  27         5.2.1 Parity checking and packet re-synchronization
  28         5.2.2 One/Three finger touch
  29         5.2.3 Two finger touch
  30  6. Hardware version 3
  31     6.1 Registers
  32     6.2 Native absolute mode 6 byte packet format
  33         6.2.1 One/Three finger touch
  34         6.2.2 Two finger touch
  35  7. Hardware version 4
  36     7.1 Registers
  37     7.2 Native absolute mode 6 byte packet format
  38         7.2.1 Status packet
  39         7.2.2 Head packet
  40         7.2.3 Motion packet
  41  8. Trackpoint (for Hardware version 3 and 4)
  42     8.1 Registers
  43     8.2 Native relative mode 6 byte packet format
  44         8.2.1 Status Packet
  45
  46
  47
  48 1. Introduction
  49    ~~~~~~~~~~~~
  50
  51 Currently the Linux Elantech touchpad driver is aware of four different
  52 hardware versions unimaginatively called version 1,version 2, version 3
  53 and version 4. Version 1 is found in "older" laptops and uses 4 bytes per
  54 packet. Version 2 seems to be introduced with the EeePC and uses 6 bytes
  55 per packet, and provides additional features such as position of two fingers,
  56 and width of the touch.  Hardware version 3 uses 6 bytes per packet (and
  57 for 2 fingers the concatenation of two 6 bytes packets) and allows tracking
  58 of up to 3 fingers. Hardware version 4 uses 6 bytes per packet, and can
  59 combine a status packet with multiple head or motion packets. Hardware version
  60 4 allows tracking up to 5 fingers.
  61
  62 Some Hardware version 3 and version 4 also have a trackpoint which uses a
  63 separate packet format. It is also 6 bytes per packet.
  64
  65 The driver tries to support both hardware versions and should be compatible
  66 with the Xorg Synaptics touchpad driver and its graphical configuration
  67 utilities.
  68
  69 Note that a mouse button is also associated with either the touchpad or the
  70 trackpoint when a trackpoint is available.  Disabling the Touchpad in xorg
  71 (TouchPadOff=0) will also disable the buttons associated with the touchpad.
  72
  73 Additionally the operation of the touchpad can be altered by adjusting the
  74 contents of some of its internal registers. These registers are represented
  75 by the driver as sysfs entries under /sys/bus/serio/drivers/psmouse/serio?
  76 that can be read from and written to.
  77
  78 Currently only the registers for hardware version 1 are somewhat understood.
  79 Hardware version 2 seems to use some of the same registers but it is not
  80 known whether the bits in the registers represent the same thing or might
  81 have changed their meaning.
  82
  83 On top of that, some register settings have effect only when the touchpad is
  84 in relative mode and not in absolute mode. As the Linux Elantech touchpad
  85 driver always puts the hardware into absolute mode not all information
  86 mentioned below can be used immediately. But because there is no freely
  87 available Elantech documentation the information is provided here anyway for
  88 completeness sake.
  89
  90
  91 /////////////////////////////////////////////////////////////////////////////
  92
  93
  94 2. Extra knobs
  95    ~~~~~~~~~~~
  96
  97 Currently the Linux Elantech touchpad driver provides three extra knobs under
  98 /sys/bus/serio/drivers/psmouse/serio? for the user.
  99
 100 * debug
 101
 102    Turn different levels of debugging ON or OFF.
 103
 104    By echoing "0" to this file all debugging will be turned OFF.
 105
 106    Currently a value of "1" will turn on some basic debugging and a value of
 107    "2" will turn on packet debugging. For hardware version 1 the default is
 108    OFF. For version 2 the default is "1".
 109
 110    Turning packet debugging on will make the driver dump every packet
 111    received to the syslog before processing it. Be warned that this can
 112    generate quite a lot of data!
 113
 114 * paritycheck
 115
 116    Turns parity checking ON or OFF.
 117
 118    By echoing "0" to this file parity checking will be turned OFF. Any
 119    non-zero value will turn it ON. For hardware version 1 the default is ON.
 120    For version 2 the default it is OFF.
 121
 122    Hardware version 1 provides basic data integrity verification by
 123    calculating a parity bit for the last 3 bytes of each packet. The driver
 124    can check these bits and reject any packet that appears corrupted. Using
 125    this knob you can bypass that check.
 126
 127    Hardware version 2 does not provide the same parity bits. Only some basic
 128    data consistency checking can be done. For now checking is disabled by
 129    default. Currently even turning it on will do nothing.
 130
 131 * crc_enabled
 132
 133    Sets crc_enabled to 0/1. The name "crc_enabled" is the official name of
 134    this integrity check, even though it is not an actual cyclic redundancy
 135    check.
 136
 137    Depending on the state of crc_enabled, certain basic data integrity
 138    verification is done by the driver on hardware version 3 and 4. The
 139    driver will reject any packet that appears corrupted. Using this knob,
 140    The state of crc_enabled can be altered with this knob.
 141
 142    Reading the crc_enabled value will show the active value. Echoing
 143    "0" or "1" to this file will set the state to "0" or "1".
 144
 145 /////////////////////////////////////////////////////////////////////////////
 146
 147 3. Differentiating hardware versions
 148    =================================
 149
 150 To detect the hardware version, read the version number as param[0].param[1].param[2]
 151
 152  4 bytes version: (after the arrow is the name given in the Dell-provided driver)
 153  02.00.22 => EF013
 154  02.06.00 => EF019
 155 In the wild, there appear to be more versions, such as 00.01.64, 01.00.21,
 156 02.00.00, 02.00.04, 02.00.06.
 157
 158  6 bytes:
 159  02.00.30 => EF113
 160  02.08.00 => EF023
 161  02.08.XX => EF123
 162  02.0B.00 => EF215
 163  04.01.XX => Scroll_EF051
 164  04.02.XX => EF051
 165 In the wild, there appear to be more versions, such as 04.03.01, 04.04.11. There
 166 appears to be almost no difference, except for EF113, which does not report
 167 pressure/width and has different data consistency checks.
 168
 169 Probably all the versions with param[0] <= 01 can be considered as
 170 4 bytes/firmware 1. The versions < 02.08.00, with the exception of 02.00.30, as
 171 4 bytes/firmware 2. Everything >= 02.08.00 can be considered as 6 bytes.
 172
 173 /////////////////////////////////////////////////////////////////////////////
 174
 175 4. Hardware version 1
 176    ==================
 177
 178 4.1 Registers
 179     ~~~~~~~~~
 180
 181 By echoing a hexadecimal value to a register it contents can be altered.
 182
 183 For example:
 184
 185    echo -n 0x16 > reg_10
 186
 187 * reg_10
 188
 189    bit   7   6   5   4   3   2   1   0
 190          B   C   T   D   L   A   S   E
 191
 192          E: 1 = enable smart edges unconditionally
 193          S: 1 = enable smart edges only when dragging
 194          A: 1 = absolute mode (needs 4 byte packets, see reg_11)
 195          L: 1 = enable drag lock (see reg_22)
 196          D: 1 = disable dynamic resolution
 197          T: 1 = disable tapping
 198          C: 1 = enable corner tap
 199          B: 1 = swap left and right button
 200
 201 * reg_11
 202
 203    bit   7   6   5   4   3   2   1   0
 204          1   0   0   H   V   1   F   P
 205
 206          P: 1 = enable parity checking for relative mode
 207          F: 1 = enable native 4 byte packet mode
 208          V: 1 = enable vertical scroll area
 209          H: 1 = enable horizontal scroll area
 210
 211 * reg_20
 212
 213          single finger width?
 214
 215 * reg_21
 216
 217          scroll area width (small: 0x40 ... wide: 0xff)
 218
 219 * reg_22
 220
 221          drag lock time out (short: 0x14 ... long: 0xfe;
 222                              0xff = tap again to release)
 223
 224 * reg_23
 225
 226          tap make timeout?
 227
 228 * reg_24
 229
 230          tap release timeout?
 231
 232 * reg_25
 233
 234          smart edge cursor speed (0x02 = slow, 0x03 = medium, 0x04 = fast)
 235
 236 * reg_26
 237
 238          smart edge activation area width?
 239
 240
 241 4.2 Native relative mode 4 byte packet format
 242     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 243
 244 byte 0:
 245    bit   7   6   5   4   3   2   1   0
 246          c   c  p2  p1   1   M   R   L
 247
 248          L, R, M = 1 when Left, Right, Middle mouse button pressed
 249             some models have M as byte 3 odd parity bit
 250          when parity checking is enabled (reg_11, P = 1):
 251             p1..p2 = byte 1 and 2 odd parity bit
 252          c = 1 when corner tap detected
 253
 254 byte 1:
 255    bit   7   6   5   4   3   2   1   0
 256         dx7 dx6 dx5 dx4 dx3 dx2 dx1 dx0
 257
 258          dx7..dx0 = x movement;   positive = right, negative = left
 259          byte 1 = 0xf0 when corner tap detected
 260
 261 byte 2:
 262    bit   7   6   5   4   3   2   1   0
 263         dy7 dy6 dy5 dy4 dy3 dy2 dy1 dy0
 264
 265          dy7..dy0 = y movement;   positive = up,    negative = down
 266
 267 byte 3:
 268    parity checking enabled (reg_11, P = 1):
 269
 270       bit   7   6   5   4   3   2   1   0
 271             w   h  n1  n0  ds3 ds2 ds1 ds0
 272
 273             normally:
 274                ds3..ds0 = scroll wheel amount and direction
 275                           positive = down or left
 276                           negative = up or right
 277             when corner tap detected:
 278                ds0 = 1 when top right corner tapped
 279                ds1 = 1 when bottom right corner tapped
 280                ds2 = 1 when bottom left corner tapped
 281                ds3 = 1 when top left corner tapped
 282             n1..n0 = number of fingers on touchpad
 283                only models with firmware 2.x report this, models with
 284                firmware 1.x seem to map one, two and three finger taps
 285                directly to L, M and R mouse buttons
 286             h = 1 when horizontal scroll action
 287             w = 1 when wide finger touch?
 288
 289    otherwise (reg_11, P = 0):
 290
 291       bit   7   6   5   4   3   2   1   0
 292            ds7 ds6 ds5 ds4 ds3 ds2 ds1 ds0
 293
 294             ds7..ds0 = vertical scroll amount and direction
 295                        negative = up
 296                        positive = down
 297
 298
 299 4.3 Native absolute mode 4 byte packet format
 300     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 301
 302 EF013 and EF019 have a special behaviour (due to a bug in the firmware?), and
 303 when 1 finger is touching, the first 2 position reports must be discarded.
 304 This counting is reset whenever a different number of fingers is reported.
 305
 306 byte 0:
 307    firmware version 1.x:
 308
 309       bit   7   6   5   4   3   2   1   0
 310             D   U  p1  p2   1  p3   R   L
 311
 312             L, R = 1 when Left, Right mouse button pressed
 313             p1..p3 = byte 1..3 odd parity bit
 314             D, U = 1 when rocker switch pressed Up, Down
 315
 316    firmware version 2.x:
 317
 318       bit   7   6   5   4   3   2   1   0
 319            n1  n0  p2  p1   1  p3   R   L
 320
 321             L, R = 1 when Left, Right mouse button pressed
 322             p1..p3 = byte 1..3 odd parity bit
 323             n1..n0 = number of fingers on touchpad
 324
 325 byte 1:
 326    firmware version 1.x:
 327
 328       bit   7   6   5   4   3   2   1   0
 329             f   0  th  tw  x9  x8  y9  y8
 330
 331             tw = 1 when two finger touch
 332             th = 1 when three finger touch
 333             f  = 1 when finger touch
 334
 335    firmware version 2.x:
 336
 337       bit   7   6   5   4   3   2   1   0
 338             .   .   .   .  x9  x8  y9  y8
 339
 340 byte 2:
 341    bit   7   6   5   4   3   2   1   0
 342         x7  x6  x5  x4  x3  x2  x1  x0
 343
 344          x9..x0 = absolute x value (horizontal)
 345
 346 byte 3:
 347    bit   7   6   5   4   3   2   1   0
 348         y7  y6  y5  y4  y3  y2  y1  y0
 349
 350          y9..y0 = absolute y value (vertical)
 351
 352
 353 /////////////////////////////////////////////////////////////////////////////
 354
 355
 356 5. Hardware version 2
 357    ==================
 358
 359
 360 5.1 Registers
 361     ~~~~~~~~~
 362
 363 By echoing a hexadecimal value to a register it contents can be altered.
 364
 365 For example:
 366
 367    echo -n 0x56 > reg_10
 368
 369 * reg_10
 370
 371    bit   7   6   5   4   3   2   1   0
 372          0   1   0   1   0   1   D   0
 373
 374          D: 1 = enable drag and drop
 375
 376 * reg_11
 377
 378    bit   7   6   5   4   3   2   1   0
 379          1   0   0   0   S   0   1   0
 380
 381          S: 1 = enable vertical scroll
 382
 383 * reg_21
 384
 385          unknown (0x00)
 386
 387 * reg_22
 388
 389          drag and drop release time out (short: 0x70 ... long 0x7e;
 390                                    0x7f = never i.e. tap again to release)
 391
 392
 393 5.2 Native absolute mode 6 byte packet format
 394     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 395 5.2.1 Parity checking and packet re-synchronization
 396 There is no parity checking, however some consistency checks can be performed.
 397
 398 For instance for EF113:
 399         SA1= packet[0];
 400         A1 = packet[1];
 401         B1 = packet[2];
 402         SB1= packet[3];
 403         C1 = packet[4];
 404         D1 = packet[5];
 405         if( (((SA1 & 0x3C) != 0x3C) && ((SA1 & 0xC0) != 0x80)) || // check Byte 1
 406             (((SA1 & 0x0C) != 0x0C) && ((SA1 & 0xC0) == 0x80)) || // check Byte 1 (one finger pressed)
 407             (((SA1 & 0xC0) != 0x80) && (( A1 & 0xF0) != 0x00)) || // check Byte 2
 408             (((SB1 & 0x3E) != 0x38) && ((SA1 & 0xC0) != 0x80)) || // check Byte 4
 409             (((SB1 & 0x0E) != 0x08) && ((SA1 & 0xC0) == 0x80)) || // check Byte 4 (one finger pressed)
 410             (((SA1 & 0xC0) != 0x80) && (( C1 & 0xF0) != 0x00))  ) // check Byte 5
 411                 // error detected
 412
 413 For all the other ones, there are just a few constant bits:
 414         if( ((packet[0] & 0x0C) != 0x04) ||
 415             ((packet[3] & 0x0f) != 0x02) )
 416                 // error detected
 417
 418
 419 In case an error is detected, all the packets are shifted by one (and packet[0] is discarded).
 420
 421 5.2.2 One/Three finger touch
 422       ~~~~~~~~~~~~~~~~
 423
 424 byte 0:
 425
 426    bit   7   6   5   4   3   2   1   0
 427          n1  n0  w3  w2   .   .   R   L
 428
 429          L, R = 1 when Left, Right mouse button pressed
 430          n1..n0 = number of fingers on touchpad
 431
 432 byte 1:
 433
 434    bit   7   6   5   4   3   2   1   0
 435          p7  p6  p5  p4 x11 x10 x9  x8
 436
 437 byte 2:
 438
 439    bit   7   6   5   4   3   2   1   0
 440          x7  x6  x5  x4  x3  x2  x1  x0
 441
 442          x11..x0 = absolute x value (horizontal)
 443
 444 byte 3:
 445
 446    bit   7   6   5   4   3   2   1   0
 447          n4  vf  w1  w0   .   .   .  b2
 448
 449          n4 = set if more than 3 fingers (only in 3 fingers mode)
 450          vf = a kind of flag ? (only on EF123, 0 when finger is over one
 451               of the buttons, 1 otherwise)
 452          w3..w0 = width of the finger touch (not EF113)
 453          b2 (on EF113 only, 0 otherwise), b2.R.L indicates one button pressed:
 454                 0 = none
 455                 1 = Left
 456                 2 = Right
 457                 3 = Middle (Left and Right)
 458                 4 = Forward
 459                 5 = Back
 460                 6 = Another one
 461                 7 = Another one
 462
 463 byte 4:
 464
 465    bit   7   6   5   4   3   2   1   0
 466         p3  p1  p2  p0  y11 y10 y9  y8
 467
 468          p7..p0 = pressure (not EF113)
 469
 470 byte 5:
 471
 472    bit   7   6   5   4   3   2   1   0
 473         y7  y6  y5  y4  y3  y2  y1  y0
 474
 475          y11..y0 = absolute y value (vertical)
 476
 477
 478 5.2.3 Two finger touch
 479       ~~~~~~~~~~~~~~~~
 480
 481 Note that the two pairs of coordinates are not exactly the coordinates of the
 482 two fingers, but only the pair of the lower-left and upper-right coordinates.
 483 So the actual fingers might be situated on the other diagonal of the square
 484 defined by these two points.
 485
 486 byte 0:
 487
 488    bit   7   6   5   4   3   2   1   0
 489         n1  n0  ay8 ax8  .   .   R   L
 490
 491          L, R = 1 when Left, Right mouse button pressed
 492          n1..n0 = number of fingers on touchpad
 493
 494 byte 1:
 495
 496    bit   7   6   5   4   3   2   1   0
 497         ax7 ax6 ax5 ax4 ax3 ax2 ax1 ax0
 498
 499          ax8..ax0 = lower-left finger absolute x value
 500
 501 byte 2:
 502
 503    bit   7   6   5   4   3   2   1   0
 504         ay7 ay6 ay5 ay4 ay3 ay2 ay1 ay0
 505
 506          ay8..ay0 = lower-left finger absolute y value
 507
 508 byte 3:
 509
 510    bit   7   6   5   4   3   2   1   0
 511          .   .  by8 bx8  .   .   .   .
 512
 513 byte 4:
 514
 515    bit   7   6   5   4   3   2   1   0
 516         bx7 bx6 bx5 bx4 bx3 bx2 bx1 bx0
 517
 518          bx8..bx0 = upper-right finger absolute x value
 519
 520 byte 5:
 521
 522    bit   7   6   5   4   3   2   1   0
 523         by7 by8 by5 by4 by3 by2 by1 by0
 524
 525          by8..by0 = upper-right finger absolute y value
 526
 527 /////////////////////////////////////////////////////////////////////////////
 528
 529 6. Hardware version 3
 530    ==================
 531
 532 6.1 Registers
 533     ~~~~~~~~~
 534 * reg_10
 535
 536    bit   7   6   5   4   3   2   1   0
 537          0   0   0   0   R   F   T   A
 538
 539          A: 1 = enable absolute tracking
 540          T: 1 = enable two finger mode auto correct
 541          F: 1 = disable ABS Position Filter
 542          R: 1 = enable real hardware resolution
 543
 544 6.2 Native absolute mode 6 byte packet format
 545     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 546 1 and 3 finger touch shares the same 6-byte packet format, except that
 547 3 finger touch only reports the position of the center of all three fingers.
 548
 549 Firmware would send 12 bytes of data for 2 finger touch.
 550
 551 Note on debounce:
 552 In case the box has unstable power supply or other electricity issues, or
 553 when number of finger changes, F/W would send "debounce packet" to inform
 554 driver that the hardware is in debounce status.
 555 The debouce packet has the following signature:
 556     byte 0: 0xc4
 557     byte 1: 0xff
 558     byte 2: 0xff
 559     byte 3: 0x02
 560     byte 4: 0xff
 561     byte 5: 0xff
 562 When we encounter this kind of packet, we just ignore it.
 563
 564 6.2.1 One/Three finger touch
 565       ~~~~~~~~~~~~~~~~~~~~~~
 566
 567 byte 0:
 568
 569    bit   7   6   5   4   3   2   1   0
 570         n1  n0  w3  w2   0   1   R   L
 571
 572         L, R = 1 when Left, Right mouse button pressed
 573         n1..n0 = number of fingers on touchpad
 574
 575 byte 1:
 576
 577    bit   7   6   5   4   3   2   1   0
 578         p7  p6  p5  p4 x11 x10  x9  x8
 579
 580 byte 2:
 581
 582    bit   7   6   5   4   3   2   1   0
 583         x7  x6  x5  x4  x3  x2  x1  x0
 584
 585         x11..x0 = absolute x value (horizontal)
 586
 587 byte 3:
 588
 589    bit   7   6   5   4   3   2   1   0
 590          0   0  w1  w0   0   0   1   0
 591
 592          w3..w0 = width of the finger touch
 593
 594 byte 4:
 595
 596    bit   7   6   5   4   3   2   1   0
 597         p3  p1  p2  p0  y11 y10 y9  y8
 598
 599         p7..p0 = pressure
 600
 601 byte 5:
 602
 603    bit   7   6   5   4   3   2   1   0
 604         y7  y6  y5  y4  y3  y2  y1  y0
 605
 606         y11..y0 = absolute y value (vertical)
 607
 608 6.2.2 Two finger touch
 609       ~~~~~~~~~~~~~~~~
 610
 611 The packet format is exactly the same for two finger touch, except the hardware
 612 sends two 6 byte packets. The first packet contains data for the first finger,
 613 the second packet has data for the second finger. So for two finger touch a
 614 total of 12 bytes are sent.
 615
 616 /////////////////////////////////////////////////////////////////////////////
 617
 618 7. Hardware version 4
 619    ==================
 620
 621 7.1 Registers
 622     ~~~~~~~~~
 623 * reg_07
 624
 625    bit   7   6   5   4   3   2   1   0
 626          0   0   0   0   0   0   0   A
 627
 628          A: 1 = enable absolute tracking
 629
 630 7.2 Native absolute mode 6 byte packet format
 631     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 632 v4 hardware is a true multitouch touchpad, capable of tracking up to 5 fingers.
 633 Unfortunately, due to PS/2's limited bandwidth, its packet format is rather
 634 complex.
 635
 636 Whenever the numbers or identities of the fingers changes, the hardware sends a
 637 status packet to indicate how many and which fingers is on touchpad, followed by
 638 head packets or motion packets. A head packet contains data of finger id, finger
 639 position (absolute x, y values), width, and pressure. A motion packet contains
 640 two fingers' position delta.
 641
 642 For example, when status packet tells there are 2 fingers on touchpad, then we
 643 can expect two following head packets. If the finger status doesn't change,
 644 the following packets would be motion packets, only sending delta of finger
 645 position, until we receive a status packet.
 646
 647 One exception is one finger touch. when a status packet tells us there is only
 648 one finger, the hardware would just send head packets afterwards.
 649
 650 7.2.1 Status packet
 651       ~~~~~~~~~~~~~
 652
 653 byte 0:
 654
 655    bit   7   6   5   4   3   2   1   0
 656          .   .   .   .   0   1   R   L
 657
 658          L, R = 1 when Left, Right mouse button pressed
 659
 660 byte 1:
 661
 662    bit   7   6   5   4   3   2   1   0
 663          .   .   . ft4 ft3 ft2 ft1 ft0
 664
 665          ft4 ft3 ft2 ft1 ft0 ftn = 1 when finger n is on touchpad
 666
 667 byte 2: not used
 668
 669 byte 3:
 670
 671    bit   7   6   5   4   3   2   1   0
 672          .   .   .   1   0   0   0   0
 673
 674          constant bits
 675
 676 byte 4:
 677
 678    bit   7   6   5   4   3   2   1   0
 679          p   .   .   .   .   .   .   .
 680
 681          p = 1 for palm
 682
 683 byte 5: not used
 684
 685 7.2.2 Head packet
 686       ~~~~~~~~~~~
 687
 688 byte 0:
 689
 690    bit   7   6   5   4   3   2   1   0
 691         w3  w2  w1  w0   0   1   R   L
 692
 693         L, R = 1 when Left, Right mouse button pressed
 694         w3..w0 = finger width (spans how many trace lines)
 695
 696 byte 1:
 697
 698    bit   7   6   5   4   3   2   1   0
 699         p7  p6  p5  p4 x11 x10  x9  x8
 700
 701 byte 2:
 702
 703    bit   7   6   5   4   3   2   1   0
 704         x7  x6  x5  x4  x3  x2  x1  x0
 705
 706         x11..x0 = absolute x value (horizontal)
 707
 708 byte 3:
 709
 710    bit   7   6   5   4   3   2   1   0
 711        id2 id1 id0   1   0   0   0   1
 712
 713        id2..id0 = finger id
 714
 715 byte 4:
 716
 717    bit   7   6   5   4   3   2   1   0
 718         p3  p1  p2  p0  y11 y10 y9  y8
 719
 720         p7..p0 = pressure
 721
 722 byte 5:
 723
 724    bit   7   6   5   4   3   2   1   0
 725         y7  y6  y5  y4  y3  y2  y1  y0
 726
 727         y11..y0 = absolute y value (vertical)
 728
 729 7.2.3 Motion packet
 730       ~~~~~~~~~~~~~
 731
 732 byte 0:
 733
 734    bit   7   6   5   4   3   2   1   0
 735        id2 id1 id0   w   0   1   R   L
 736
 737        L, R = 1 when Left, Right mouse button pressed
 738        id2..id0 = finger id
 739        w = 1 when delta overflows (> 127 or < -128), in this case
 740        firmware sends us (delta x / 5) and (delta y  / 5)
 741
 742 byte 1:
 743
 744    bit   7   6   5   4   3   2   1   0
 745         x7  x6  x5  x4  x3  x2  x1  x0
 746
 747         x7..x0 = delta x (two's complement)
 748
 749 byte 2:
 750
 751    bit   7   6   5   4   3   2   1   0
 752         y7  y6  y5  y4  y3  y2  y1  y0
 753
 754         y7..y0 = delta y (two's complement)
 755
 756 byte 3:
 757
 758    bit   7   6   5   4   3   2   1   0
 759        id2 id1 id0   1   0   0   1   0
 760
 761        id2..id0 = finger id
 762
 763 byte 4:
 764
 765    bit   7   6   5   4   3   2   1   0
 766         x7  x6  x5  x4  x3  x2  x1  x0
 767
 768         x7..x0 = delta x (two's complement)
 769
 770 byte 5:
 771
 772    bit   7   6   5   4   3   2   1   0
 773         y7  y6  y5  y4  y3  y2  y1  y0
 774
 775         y7..y0 = delta y (two's complement)
 776
 777         byte 0 ~ 2 for one finger
 778         byte 3 ~ 5 for another
 779
 780
 781 8. Trackpoint (for Hardware version 3 and 4)
 782    =========================================
 783 8.1 Registers
 784     ~~~~~~~~~
 785 No special registers have been identified.
 786
 787 8.2 Native relative mode 6 byte packet format
 788     ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
 789 8.2.1 Status Packet
 790       ~~~~~~~~~~~~~
 791
 792 byte 0:
 793    bit   7   6   5   4   3   2   1   0
 794          0   0  sx  sy   0   M   R   L
 795 byte 1:
 796    bit   7   6   5   4   3   2   1   0
 797        ~sx   0   0   0   0   0   0   0
 798 byte 2:
 799    bit   7   6   5   4   3   2   1   0
 800        ~sy   0   0   0   0   0   0   0
 801 byte 3:
 802    bit   7   6   5   4   3   2   1   0
 803          0   0 ~sy ~sx   0   1   1   0
 804 byte 4:
 805    bit   7   6   5   4   3   2   1   0
 806         x7  x6  x5  x4  x3  x2  x1  x0
 807 byte 5:
 808    bit   7   6   5   4   3   2   1   0
 809         y7  y6  y5  y4  y3  y2  y1  y0
 810
 811
 812          x and y are written in two's complement spread
 813              over 9 bits with sx/sy the relative top bit and
 814              x7..x0 and y7..y0 the lower bits.
 815          ~sx is the inverse of sx, ~sy is the inverse of sy.
 816          The sign of y is opposite to what the input driver
 817              expects for a relative movement