2 ## This file is part of the libsigrokdecode project.
4 ## Copyright (C) 2011 Gareth McMullin <gareth@blacksphere.co.nz>
5 ## Copyright (C) 2012-2013 Uwe Hermann <uwe@hermann-uwe.de>
7 ## This program is free software; you can redistribute it and/or modify
8 ## it under the terms of the GNU General Public License as published by
9 ## the Free Software Foundation; either version 2 of the License, or
10 ## (at your option) any later version.
12 ## This program is distributed in the hope that it will be useful,
13 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
14 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
15 ## GNU General Public License for more details.
17 ## You should have received a copy of the GNU General Public License
18 ## along with this program; if not, write to the Free Software
19 ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
22 # USB signalling (low-speed and full-speed) protocol decoder
24 import sigrokdecode as srd
26 # Low-/full-speed symbols (used as states of our state machine, too).
27 # Note: Low-speed J and K are inverted compared to the full-speed J and K!
29 # (<dp>, <dm>): <symbol/state>
36 # (<dp>, <dm>): <symbol/state>
43 class Decoder(srd.Decoder):
46 name = 'USB signalling'
47 longname = 'Universal Serial Bus (LS/FS) signalling'
48 desc = 'USB (low-speed and full-speed) signalling protocol.'
51 outputs = ['usb_signalling']
53 {'id': 'dp', 'name': 'D+', 'desc': 'USB D+ signal'},
54 {'id': 'dm', 'name': 'D-', 'desc': 'USB D- signal'},
58 'signalling': ['Signalling', 'full-speed'],
61 ['Text', 'Human-readable text']
65 self.sym = 'J' # The "idle" state is J.
72 def start(self, metadata):
73 self.samplerate = metadata['samplerate']
74 self.out_proto = self.add(srd.OUTPUT_PROTO, 'usb_signalling')
75 self.out_ann = self.add(srd.OUTPUT_ANN, 'usb_signalling')
81 self.put(self.samplenum, self.samplenum, self.out_proto, data)
84 self.put(self.samplenum, self.samplenum, self.out_ann, data)
86 def decode(self, ss, es, data):
87 for (self.samplenum, pins) in data:
89 # Note: self.samplenum is the absolute sample number, whereas
90 # self.scount only counts the number of samples since the
91 # last change in the D+/D- lines.
94 # Ignore identical samples early on (for performance reasons).
95 if self.oldpins == pins:
97 self.oldpins, (dp, dm) = pins, pins
99 if self.options['signalling'] == 'low-speed':
100 sym = symbols_ls[dp, dm]
101 elif self.options['signalling'] == 'full-speed':
102 sym = symbols_fs[dp, dm]
104 self.putx([0, [sym]])
105 self.putp(['SYM', sym])
107 # Wait for a symbol change (i.e., change in D+/D- lines).
112 ## self.syms.append(sym + ' ')
113 ## if len(self.syms) == 16:
114 ## self.putx([0, [''.join(self.syms)]])
118 # How many bits since the last transition?
119 if self.packet != '' or self.sym != 'J':
120 if self.options['signalling'] == 'low-speed':
121 bitrate = 1500000 # 1.5Mb/s (+/- 1.5%)
122 elif self.options['signalling'] == 'full-speed':
123 bitrate = 12000000 # 12Mb/s (+/- 0.25%)
124 bitcount = int((self.scount - 1) * bitrate / self.samplerate)
128 if self.sym == 'SE0':
130 # End-Of-Packet (EOP)
131 # self.putx([0, [packet_decode(self.packet), self.packet]])
132 if self.packet != '': # FIXME?
133 self.putx([0, ['PACKET: %s' % self.packet]])
134 self.putp(['PACKET', self.packet])
136 # Longer than EOP, assume reset.
137 self.putx([0, ['RESET']])
138 self.putp(['RESET', None])
139 # self.putx([0, [self.packet]])
145 # Add bits to the packet string.
146 self.packet += '1' * bitcount
148 # Handle bit stuffing.
149 if bitcount < 6 and sym != 'SE0':
152 self.putx([0, ['BIT STUFF ERROR']])
153 self.putp(['BIT STUFF ERROR', None])