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

##
## 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 *
Commit	Line	Data
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	21	'''
c2937021	22	USB (low-speed and full-speed) protocol decoder.
156509ca	23
3cf771a5 UH	24	Electrical/signalling layer (USB spec, chapter 7):
3cf771a5 UH	25
c2937021	26	USB signalling consists of two signal lines, both driven at 3.3V
156509ca UH	27	logic levels. The signals are DP (D+) and DM (D-), and normally operate in
156509ca UH	28	differential mode.
c2937021 UH	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
156509ca	33	A state SE0 is defined where DP=DM=0. This common mode signal is used to
c2937021	34	signal a reset or end of packet. A state SE1 is defined where DP=DM=1.
156509ca UH	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
c2937021 UH	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
3cf771a5 UH	46	Protocol layer (USB spec, chapter 8):
3cf771a5 UH	47
c2937021 UH	48	Bit/byte ordering: Bits are sent onto the bus LSB-first. Multibyte fields
	49	are transmitted in little-endian order (i.e., LSB to MSB).
	50
	51	SYNC field: All packets begin with a SYNC field (8 bits).
	52
	53	Packet field format: Packets start with an SOP (Start Of Packet) delimiter
	54	that is part of the SYNC field, and end with an EOP (End Of Packet).
	55
	56	PID: A PID (packet identifier) follows the SYNC field of every packet. A PID
	57	consists of a 4-bit packet type field, and a 4 bit check field.
	58	The check field is the one's complement of the packet type field.
156509ca	59
71077f34 UH	60	Protocol output format:
	61	TODO
	62
156509ca UH	63	Details:
	64	https://en.wikipedia.org/wiki/USB
	65	http://www.usb.org/developers/docs/
	66	'''
	67
64c29e28 UH	68	from .usb import *
64c29e28 UH	69