[libsigrokdecode.git] / decoders / usb_signalling / __init__.py

##
## This file is part of the libsigrokdecode 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
##

'''
This PD decodes the USB (low-speed and full-speed) signalling protocol.

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 (EOP). 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).

Details:
https://en.wikipedia.org/wiki/USB
http://www.usb.org/developers/docs/
'''

from .pd import *
Commit	Line	Data
2dc6d41c	1	##
50bd5d25	2	## This file is part of the libsigrokdecode project.
2dc6d41c UH	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
	21	'''
4c3b1846	22	This PD decodes the USB (low-speed and full-speed) signalling protocol.
2dc6d41c UH	23
	24	Electrical/signalling layer (USB spec, chapter 7):
	25
	26	USB signalling consists of two signal lines, both driven at 3.3V
	27	logic levels. The signals are DP (D+) and DM (D-), and normally operate in
	28	differential mode.
	29
	30	Low-speed: The state where DP=1,DM=0 is K, the state DP=0,DM=1 is J.
	31	Full-speed: The state where DP=1,DM=0 is J, the state DP=0,DM=1 is K.
	32
	33	A state SE0 is defined where DP=DM=0. This common mode signal is used to
	34	signal a reset or end of packet (EOP). A state SE1 is defined where DP=DM=1.
	35
	36	Data transmitted on the USB is encoded with NRZI. A transition from J to K
	37	or vice-versa indicates a logic 0, while no transition indicates a logic 1.
	38	If 6 ones are transmitted consecutively, a zero is inserted to force a
	39	transition. This is known as bit stuffing.
	40
	41	Data is transferred at a rate of 1.5Mbit/s (low-speed) / 12Mbit/s (full-speed).
	42
	43	The SE0 transmitted to signal an end-of-packet is two bit intervals long
	44	(low-speed: 1.25uS - 1.50uS, full-speed: 160ns - 175ns).
	45
2dc6d41c UH	46	Details:
	47	https://en.wikipedia.org/wiki/USB
	48	http://www.usb.org/developers/docs/
	49	'''
	50
24c74fd3	51	from .pd import *
2dc6d41c	52