]>
Commit | Line | Data |
---|---|---|
1 | ## | |
2 | ## This file is part of the libsigrokdecode project. | |
3 | ## | |
4 | ## Copyright (C) 2011 Gareth McMullin <gareth@blacksphere.co.nz> | |
5 | ## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de> | |
6 | ## | |
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. | |
11 | ## | |
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. | |
16 | ## | |
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 | |
20 | ## | |
21 | ||
22 | # USB signalling (low-speed and full-speed) protocol decoder | |
23 | ||
24 | import sigrokdecode as srd | |
25 | ||
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! | |
28 | symbols_ls = { | |
29 | # (<dp>, <dm>): <symbol/state> | |
30 | (0, 0): 'SE0', | |
31 | (1, 0): 'K', | |
32 | (0, 1): 'J', | |
33 | (1, 1): 'SE1', | |
34 | } | |
35 | symbols_fs = { | |
36 | # (<dp>, <dm>): <symbol/state> | |
37 | (0, 0): 'SE0', | |
38 | (1, 0): 'J', | |
39 | (0, 1): 'K', | |
40 | (1, 1): 'SE1', | |
41 | } | |
42 | ||
43 | class Decoder(srd.Decoder): | |
44 | api_version = 1 | |
45 | id = 'usb_signalling' | |
46 | name = 'USB signalling' | |
47 | longname = 'Universal Serial Bus (LS/FS) signalling' | |
48 | desc = 'USB (low-speed and full-speed) signalling protocol.' | |
49 | license = 'gplv2+' | |
50 | inputs = ['logic'] | |
51 | outputs = ['usb_signalling'] | |
52 | probes = [ | |
53 | {'id': 'dp', 'name': 'D+', 'desc': 'USB D+ signal'}, | |
54 | {'id': 'dm', 'name': 'D-', 'desc': 'USB D- signal'}, | |
55 | ] | |
56 | optional_probes = [] | |
57 | options = { | |
58 | 'signalling': ['Signalling', 'full-speed'], | |
59 | } | |
60 | annotations = [ | |
61 | ['Text', 'Human-readable text'] | |
62 | ] | |
63 | ||
64 | def __init__(self): | |
65 | self.sym = 'J' # The "idle" state is J. | |
66 | self.samplenum = 0 | |
67 | self.scount = 0 | |
68 | self.packet = '' | |
69 | self.syms = [] | |
70 | self.oldpins = None | |
71 | ||
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') | |
76 | ||
77 | def report(self): | |
78 | pass | |
79 | ||
80 | def decode(self, ss, es, data): | |
81 | for (self.samplenum, pins) in data: | |
82 | ||
83 | # Note: self.samplenum is the absolute sample number, whereas | |
84 | # self.scount only counts the number of samples since the | |
85 | # last change in the D+/D- lines. | |
86 | self.scount += 1 | |
87 | ||
88 | # Ignore identical samples early on (for performance reasons). | |
89 | if self.oldpins == pins: | |
90 | continue | |
91 | self.oldpins, (dp, dm) = pins, pins | |
92 | ||
93 | if self.options['signalling'] == 'low-speed': | |
94 | sym = symbols_ls[dp, dm] | |
95 | elif self.options['signalling'] == 'full-speed': | |
96 | sym = symbols_fs[dp, dm] | |
97 | ||
98 | self.put(0, 0, self.out_ann, [0, [sym]]) | |
99 | self.put(0, 0, self.out_proto, ['SYM', sym]) | |
100 | ||
101 | # Wait for a symbol change (i.e., change in D+/D- lines). | |
102 | if sym == self.sym: | |
103 | continue | |
104 | ||
105 | ## # Debug code: | |
106 | ## self.syms.append(sym + ' ') | |
107 | ## if len(self.syms) == 16: | |
108 | ## self.put(0, 0, self.out_ann, [0, [''.join(self.syms)]]) | |
109 | ## self.syms = [] | |
110 | # continue | |
111 | ||
112 | # How many bits since the last transition? | |
113 | if self.packet != '' or self.sym != 'J': | |
114 | if self.options['signalling'] == 'low-speed': | |
115 | bitrate = 1500000 # 1.5Mb/s (+/- 1.5%) | |
116 | elif self.options['signalling'] == 'full-speed': | |
117 | bitrate = 12000000 # 12Mb/s (+/- 0.25%) | |
118 | bitcount = int((self.scount - 1) * bitrate / self.samplerate) | |
119 | else: | |
120 | bitcount = 0 | |
121 | ||
122 | if self.sym == 'SE0': | |
123 | if bitcount == 1: | |
124 | # End-Of-Packet (EOP) | |
125 | # self.put(0, 0, self.out_ann, | |
126 | # [0, [packet_decode(self.packet), self.packet]]) | |
127 | if self.packet != '': # FIXME? | |
128 | self.put(0, 0, self.out_ann, [0, ['PACKET: %s' % self.packet]]) | |
129 | self.put(0, 0, self.out_proto, ['PACKET', self.packet]) | |
130 | else: | |
131 | # Longer than EOP, assume reset. | |
132 | self.put(0, 0, self.out_ann, [0, ['RESET']]) | |
133 | self.put(0, 0, self.out_proto, ['RESET', None]) | |
134 | # self.put(0, 0, self.out_ann, [0, [self.packet]]) | |
135 | self.scount = 0 | |
136 | self.sym = sym | |
137 | self.packet = '' | |
138 | continue | |
139 | ||
140 | # Add bits to the packet string. | |
141 | self.packet += '1' * bitcount | |
142 | ||
143 | # Handle bit stuffing. | |
144 | if bitcount < 6 and sym != 'SE0': | |
145 | self.packet += '0' | |
146 | elif bitcount > 6: | |
147 | self.put(0, 0, self.out_ann, [0, ['BIT STUFF ERROR']]) | |
148 | self.put(0, 0, self.out_proto, ['BIT STUFF ERROR', None]) | |
149 | ||
150 | self.scount = 0 | |
151 | self.sym = sym | |
152 |