2 ## This file is part of the libsigrokdecode project.
4 ## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
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.
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.
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
22 USB (low-speed and full-speed) packet protocol decoder.
24 Protocol layer (USB spec, chapter 8):
26 Bit/byte ordering: Bits are sent onto the bus LSB-first. Multibyte fields
27 are transmitted in little-endian order (i.e., LSB to MSB).
29 SYNC field: All packets begin with a SYNC field (8 bits).
31 Packet field format: Packets start with an SOP (Start Of Packet) delimiter
32 that is part of the SYNC field, and end with an EOP (End Of Packet).
34 PID: A PID (packet identifier) follows the SYNC field of every packet. A PID
35 consists of a 4-bit packet type field, and a 4 bit check field.
36 The check field is the one's complement of the packet type field.
38 Protocol output format:
42 https://en.wikipedia.org/wiki/USB
43 http://www.usb.org/developers/docs/