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64c29e28 UH |
1 | ## |
2 | ## This file is part of the sigrok project. | |
3 | ## | |
4 | ## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de> | |
5 | ## | |
6 | ## This program is free software; you can redistribute it and/or modify | |
7 | ## it under the terms of the GNU General Public License as published by | |
8 | ## the Free Software Foundation; either version 2 of the License, or | |
9 | ## (at your option) any later version. | |
10 | ## | |
11 | ## This program is distributed in the hope that it will be useful, | |
12 | ## but WITHOUT ANY WARRANTY; without even the implied warranty of | |
13 | ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
14 | ## GNU General Public License for more details. | |
15 | ## | |
16 | ## You should have received a copy of the GNU General Public License | |
17 | ## along with this program; if not, write to the Free Software | |
18 | ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
19 | ## | |
20 | ||
156509ca UH |
21 | ''' |
22 | USB (full-speed) protocol decoder. | |
23 | ||
24 | Full-speed USB signalling consists of two signal lines, both driven at 3.3V | |
25 | logic levels. The signals are DP (D+) and DM (D-), and normally operate in | |
26 | differential mode. | |
27 | The state where DP=1,DM=0 is J, the state DP=0,DM=1 is K. | |
28 | A state SE0 is defined where DP=DM=0. This common mode signal is used to | |
29 | signal a reset or end of packet. | |
30 | ||
31 | Data transmitted on the USB is encoded with NRZI. A transition from J to K | |
32 | or vice-versa indicates a logic 0, while no transition indicates a logic 1. | |
33 | If 6 ones are transmitted consecutively, a zero is inserted to force a | |
34 | transition. This is known as bit stuffing. Data is transferred at a rate | |
35 | of 12Mbit/s. The SE0 transmitted to signal an end-of-packet is two bit | |
36 | intervals long. | |
37 | ||
71077f34 UH |
38 | Protocol output format: |
39 | TODO | |
40 | ||
156509ca UH |
41 | Details: |
42 | https://en.wikipedia.org/wiki/USB | |
43 | http://www.usb.org/developers/docs/ | |
44 | ''' | |
45 | ||
64c29e28 UH |
46 | from .usb import * |
47 |