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1 | ## | |
2 | ## This file is part of the sigrok project. | |
3 | ## | |
4 | ## Copyright (C) 2011 Gareth McMullin <gareth@blacksphere.co.nz> | |
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 | # | |
22 | # USB Full-speed protocol decoder | |
23 | # | |
24 | # Full-speed USB signalling consists of two signal lines, both driven at 3.3V | |
25 | # logic levels. The signals are DP (D+) and DM (D-), and normally operate in | |
26 | # differential mode. | |
27 | # The state where DP=1,DM=0 is J, the state DP=0,DM=1 is K. | |
28 | # A state SE0 is defined where DP=DM=0. This common mode signal is used to | |
29 | # signal a reset or end of packet. | |
30 | # | |
31 | # Data transmitted on the USB is encoded with NRZI. A transition from J to K | |
32 | # or vice-versa indicates a logic 0, while no transition indicates a logic 1. | |
33 | # If 6 ones are transmitted consecutively, a zero is inserted to force a | |
34 | # transition. This is known as bit stuffing. Data is transferred at a rate | |
35 | # of 12Mbit/s. The SE0 transmitted to signal an end-of-packet is two bit | |
36 | # intervals long. | |
37 | # | |
38 | # Details: | |
39 | # https://en.wikipedia.org/wiki/USB | |
40 | # http://www.usb.org/developers/docs/ | |
41 | # | |
42 | ||
43 | import sigrokdecode as srd | |
44 | ||
45 | # States | |
46 | SE0, J, K, SE1 = 0, 1, 2, 3 | |
47 | ||
48 | # ... | |
49 | syms = { | |
50 | (0, 0): SE0, | |
51 | (1, 0): J, | |
52 | (0, 1): K, | |
53 | (1, 1): SE1, | |
54 | } | |
55 | ||
56 | # ... | |
57 | pids = { | |
58 | '10000111': 'OUT', # Tokens | |
59 | '10010110': 'IN', | |
60 | '10100101': 'SOF', | |
61 | '10110100': 'SETUP', | |
62 | '11000011': 'DATA0', # Data | |
63 | '11010010': 'DATA1', | |
64 | '01001011': 'ACK', # Handshake | |
65 | '01011010': 'NAK', | |
66 | '01111000': 'STALL', | |
67 | '01101001': 'NYET', | |
68 | } | |
69 | ||
70 | def bitstr_to_num(bitstr): | |
71 | if not bitstr: | |
72 | return 0 | |
73 | l = list(bitstr) | |
74 | l.reverse() | |
75 | return int(''.join(l), 2) | |
76 | ||
77 | def packet_decode(packet): | |
78 | sync = packet[:8] | |
79 | pid = packet[8:16] | |
80 | pid = pids.get(pid, pid) | |
81 | ||
82 | # Remove CRC. | |
83 | if pid in ('OUT', 'IN', 'SOF', 'SETUP'): | |
84 | data = packet[16:-5] | |
85 | if pid == 'SOF': | |
86 | data = str(bitstr_to_num(data)) | |
87 | else: | |
88 | dev = bitstr_to_num(data[:7]) | |
89 | ep = bitstr_to_num(data[7:]) | |
90 | data = 'DEV %d EP %d' % (dev, ep) | |
91 | ||
92 | elif pid in ('DATA0', 'DATA1'): | |
93 | data = packet[16:-16] | |
94 | tmp = '' | |
95 | while data: | |
96 | tmp += '%02x ' % bitstr_to_num(data[:8]) | |
97 | data = data[8:] | |
98 | data = tmp | |
99 | else: | |
100 | data = packet[16:] | |
101 | ||
102 | if sync != '00000001': | |
103 | return 'SYNC INVALID!' | |
104 | ||
105 | return pid + ' ' + data | |
106 | ||
107 | class Decoder(srd.Decoder): | |
108 | id = 'usb' | |
109 | name = 'USB' | |
110 | longname = 'Universal Serial Bus' | |
111 | desc = 'Universal Serial Bus' | |
112 | longdesc = '...longdesc...' | |
113 | author = 'Gareth McMullin' | |
114 | email = 'gareth@blacksphere.co.nz' | |
115 | license = 'gplv2+' | |
116 | inputs = ['logic'] | |
117 | outputs = ['usb'] | |
118 | probes = [ | |
119 | {'id': 'dp', 'name': 'D+', 'desc': 'USB D+ signal'}, | |
120 | {'id': 'dm', 'name': 'D-', 'desc': 'USB D- signal'}, | |
121 | ] | |
122 | options = {} | |
123 | annotations = [ | |
124 | ['TODO', 'TODO'] | |
125 | ] | |
126 | ||
127 | def __init__(self): | |
128 | pass | |
129 | ||
130 | def start(self, metadata): | |
131 | self.rate = metadata['samplerate'] | |
132 | ||
133 | # self.out_proto = self.add(srd.OUTPUT_PROTO, 'usb') | |
134 | self.out_ann = self.add(srd.OUTPUT_ANN, 'usb') | |
135 | ||
136 | if self.rate < 48000000: | |
137 | raise Exception('Sample rate not sufficient for USB decoding') | |
138 | ||
139 | # Initialise decoder state. | |
140 | self.sym = J | |
141 | self.scount = 0 | |
142 | self.packet = '' | |
143 | ||
144 | def decode(self, ss, es, data): | |
145 | ||
146 | # FIXME | |
147 | # for (samplenum, (dp, dm, x, y, z, a)) in data: | |
148 | for (samplenum, (dm, dp)) in data: | |
149 | ||
150 | self.scount += 1 | |
151 | ||
152 | sym = syms[dp, dm] | |
153 | ||
154 | # ... | |
155 | if sym == self.sym: | |
156 | continue | |
157 | ||
158 | if self.scount == 1: | |
159 | # We ignore single sample width pulses. | |
160 | # I sometimes get these with the OLS. | |
161 | self.sym = sym | |
162 | self.scount = 0 | |
163 | continue | |
164 | ||
165 | # How many bits since the last transition? | |
166 | if self.packet != '' or self.sym != J: | |
167 | bitcount = int((self.scount - 1) * 12000000 / self.rate) | |
168 | else: | |
169 | bitcount = 0 | |
170 | ||
171 | if self.sym == SE0: | |
172 | if bitcount == 1: | |
173 | # End-Of-Packet (EOP) | |
174 | self.put(0, 0, self.out_ann, | |
175 | [0, [packet_decode(self.packet), self.packet]]) | |
176 | else: | |
177 | # Longer than EOP, assume reset. | |
178 | self.put(0, 0, self.out_ann, [0, ['RESET']]) | |
179 | self.scount = 0 | |
180 | self.sym = sym | |
181 | self.packet = '' | |
182 | continue | |
183 | ||
184 | # Add bits to the packet string. | |
185 | self.packet += '1' * bitcount | |
186 | ||
187 | # Handle bit stuffing. | |
188 | if bitcount < 6 and sym != SE0: | |
189 | self.packet += '0' | |
190 | elif bitcount > 6: | |
191 | self.put(0, 0, self.out_ann, [0, ['BIT STUFF ERROR']]) | |
192 | ||
193 | self.scount = 0 | |
194 | self.sym = sym | |
195 |