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Diffstat (limited to 'decoders/usb/__init__.py')
| -rw-r--r-- | decoders/usb/__init__.py | 69 |
1 files changed, 0 insertions, 69 deletions
diff --git a/decoders/usb/__init__.py b/decoders/usb/__init__.py deleted file mode 100644 index 313c495..0000000 --- a/decoders/usb/__init__.py +++ /dev/null @@ -1,69 +0,0 @@ -## -## This file is part of the sigrok project. -## -## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de> -## -## This program is free software; you can redistribute it and/or modify -## it under the terms of the GNU General Public License as published by -## the Free Software Foundation; either version 2 of the License, or -## (at your option) any later version. -## -## This program is distributed in the hope that it will be useful, -## but WITHOUT ANY WARRANTY; without even the implied warranty of -## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the -## GNU General Public License for more details. -## -## You should have received a copy of the GNU General Public License -## along with this program; if not, write to the Free Software -## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA -## - -''' -USB (low-speed and full-speed) protocol decoder. - -Electrical/signalling layer (USB spec, chapter 7): - -USB signalling consists of two signal lines, both driven at 3.3V -logic levels. The signals are DP (D+) and DM (D-), and normally operate in -differential mode. - -Low-speed: The state where DP=1,DM=0 is K, the state DP=0,DM=1 is J. -Full-speed: The state where DP=1,DM=0 is J, the state DP=0,DM=1 is K. - -A state SE0 is defined where DP=DM=0. This common mode signal is used to -signal a reset or end of packet. A state SE1 is defined where DP=DM=1. - -Data transmitted on the USB is encoded with NRZI. A transition from J to K -or vice-versa indicates a logic 0, while no transition indicates a logic 1. -If 6 ones are transmitted consecutively, a zero is inserted to force a -transition. This is known as bit stuffing. - -Data is transferred at a rate of 1.5Mbit/s (low-speed) / 12Mbit/s (full-speed). - -The SE0 transmitted to signal an end-of-packet is two bit intervals long -(low-speed: 1.25uS - 1.50uS, full-speed: 160ns - 175ns). - -Protocol layer (USB spec, chapter 8): - -Bit/byte ordering: Bits are sent onto the bus LSB-first. Multibyte fields -are transmitted in little-endian order (i.e., LSB to MSB). - -SYNC field: All packets begin with a SYNC field (8 bits). - -Packet field format: Packets start with an SOP (Start Of Packet) delimiter -that is part of the SYNC field, and end with an EOP (End Of Packet). - -PID: A PID (packet identifier) follows the SYNC field of every packet. A PID -consists of a 4-bit packet type field, and a 4 bit check field. -The check field is the one's complement of the packet type field. - -Protocol output format: -TODO - -Details: -https://en.wikipedia.org/wiki/USB -http://www.usb.org/developers/docs/ -''' - -from .usb import * - |