Tonight, i’ve tryed to analyse more the header part, and understand how data part work. And… found something !
Header part
After a long session of touching the screen, and dumping the first 32 bytes, here is the current header decomposition :
Structure
=========
Idx Name Values(hex)
0 Format 5b
1 Format 5d
2 Request ID *
3 Unknown 1
4 Unknown c1,c3
5 Unknown 1
6 Unknown 0
7 Unknown 1
8 Unknown *
9 Unknown *
10 BufferType FL [01][012] 00, 01, 02, 10, 11, 12 < order when no touch ?
11 Unknown 0
12 Unknown 1d,2b
13 Unknown 1
15 Unknown bc,b6
16 Unknown [08][cd] 0 when touching ?
17 Unknown * 17/18 seem a value who stay the same in time
18 Unknown * when touching (except changing them every 2s)
19 Unknown 4*
Special cases
=============
When len is 845, we always get same frame (32 bits):
5b 5d b6 03 45 02 02 01 01 bc 01 15 00 6e 10 12
02 01 10 13 02 01 10 11 03 01 10 14 03 01 10 15
When len is :
* 463 - 4(c7) - 10(10)
* 471 - 4(c7) - 10(11)
* 467 - 4(c7) - 10(12)
* 457 - 4(c1) - 10(00)
* 465 - 4(c1) - 10(01) 19(4d 4e)
* 467 - 4(c1) - 10(01) 19(4c 4d)
* 463 - 4(c1) - 10(01) 19(4d)
* 465 - 4(c1) - 10(02)
* 469 - 4(c7) - 10(12)
You might not understand at all the header, cause everything is Unknown (i don’t understand too.) But i’ve understand that the data part is changing from the byte 10. The 6 differents values represent a data channel :
- 0x00: Unknown (maybe a sync signal ?)
- 0x01: Sensor 1 signal
- 0x02: Sensor 1 signal (nearly the same as 0x01, but not :/)
- 0x10: Unknown (maybe a sync signal ?)
- 0x11: Sensor 2 signal
- 0x12: Sensor 2 signal (nearly the same as 0x11)
Data part
And… to understand more the data part, i’ve tryed to draw the data part on a line (green = 0x01, blank = 0x02): X represent the index (starting from 20), Y value represent the byte at the index :
I’ve tryed to convert data to {unsigned|signed}{short,int,float}, without success.
And i’m stuck. I see thing changing fast, i see position of my finger on the data. Do i need signal analysis ?
So, i’ve write to nextwindow, and ask more information about protocol part, and analysis part. I hope they will respond to me 🙂