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notes.md

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Notes

This is the new dumping ground of discoveries and notes, such that the README.md file can stay clean.

On Open questions

Does the screen report which MPP version was used?

IptsPenMetadata Does not seem to carry this information it is pretty much identical between all three pens;

IptsPenGeneral

64 bytes

 50 4e 4a 00 9a 99 99 41  49 9e 00 00 00 00 01 02 FF FF ...
|A          |------------|seq        |--------|  |------

A: 16 bit counter:

  • Slim pen 2 increments at 288207-288358
  • Metapen M1 increments at 287894-289429
  • Metapen M2 increments at 287894-288279 Seq; Counter only got below 16 bit counts in recording. Seq matches IptsPenMetadata.C

IptsPenMetadata

16 bytes

 23 9d 00 00 01 06 06 01 ff ff ff ff ff ff ff ff
|C          |T |R |------------------------------
  • C: Increments, but only every 7 entries, This matches seq from IptsPenGeneral. Oh, Quo filed a PR that includes this as group id. Makes sense as it only increments once for each group of frames.
  • T: C increments if this is 0x01, sequence is 0x01, 0x04, 0x02, 0x05, 0x06, 0x0a, 0x0d
  • R: Follows C? T at 0x01 has this at 0x06, sequence is: 0x06, 0x07, 0x09, 0x0a, 0x0a, 0x0b, 0x08

No differences between the pens.

IptsPenDetection

16 bytes

 10 0c 01 00 c8 13 01 00 01 00 00 00 02 0d 08 80 
| D1  |F1|--| D2  |F2|.... Fn...

D1 and D2 seem to be values relating to each other. Unique D1 & D2 pairs, for Metapen M1:

  920    328 
 1100      0 
 2200      0 
 5652   5012 
12352  20256 
16561  23666 
19365  18728 
22608  20048 
32998  32850 
38730  37456 
63804   8256

For Metapen M2 and Slim Pen 2:

  920    328 
 1100      0 
 2200      0 
 3088   5064 
 5652   5012 
12352  20256 
16561  23666 
19365  18728 
22608  20048 
32998  32850 
38730  37456 
63804   8256 
65103   2064

The flags may indicate contact with the screen;

IptsPenDetection: 98 03 02 00 48 01 02 00 01 03 00 00 05 0a 0b 80 
IptsPenDetection: 40 30 04 00 20 4f 04 00 01 04 00 00 02 0d 08 80 
IptsPenDetection: 50 58 00 00 50 4e 00 00 01 03 00 00 00 01 06 80 
IptsPenDetection: 3c f9 03 00 40 20 04 00 04 03 03 00 07 04 07 80 
IptsPenDetection: 4c 04 00 00 00 00 00 00 01 03 03 00 03 02 09 80 
IptsPenDetection: 4a 97 00 00 50 92 00 00 04 00 00 00 04 05 0a 80 
IptsPenDetection: 4a 97 00 00 50 92 00 00 04 00 00 00 04 06 0a 80 
IptsPenDetection: 98 03 02 00 48 01 02 00 04 03 03 00 05 0a 0b 80 
                                         |c |

The c column does seem to switch from 01 to 04, but not much else here.

IptsMagnitude

 2A 13 29 14 01 FF FF FF 00 00 .. u32[n]?
|x1|y1|x2|y2|-----------| u32 x[IPTS_COLUMNS + 2] ... | u32[2] (0x00) | u32 y[IPTS_ROWS + 2]
  • x1 and x2 are always one apart, order varies. They can go to 255 (pen raised?)
  • y1 and y2 are always one apart, order varies. They can go to 255 (pen raised?)
  • Are these measurement strength, one of the patents refers to ratio of the two hightest bins for positioning.
./irpmon_thcbase.py comparison  --limit 1000  ../irp_logs_thcbase/2024_02_11_irp_thcbase_diginfo_3pen/2024_02_11_irp_thcbase_slim_pen_2.log.gz ../irp_logs_thcbase/2024_02_11_irp_thcbase_diginfo_3pen/2024_02_11_irp_thcbase_metapen_m1.log.gz ../irp_logs_thcbase/2024_02_11_irp_thcbase_diginfo_3pen/2024_02_11_irp_thcbase_metapen_m2.log.gz

IptsTouchedAntennas

All zeros in this, but my recordings have pure pen. Seems to again hold C =from IptsPenMetadata, perhaps packed bitmask?

IptsDataSelection

Depends on the DFT window, third byte from the end is dft window type. From imhex.md:

For the majority of frames, the beginning holds the 16 magnitudes for x and y. The end block is always 12 bytes and holds the dft window type.