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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