]>
Commit | Line | Data |
---|---|---|
1 | ## | |
2 | ## This file is part of the libsigrokdecode project. | |
3 | ## | |
4 | ## Copyright (C) 2016 Anthony Symons <antus@pcmhacking.net> | |
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, see <http://www.gnu.org/licenses/>. | |
18 | ## | |
19 | ||
20 | import sigrokdecode as srd | |
21 | ||
22 | class SamplerateError(Exception): | |
23 | pass | |
24 | ||
25 | def timeuf(t): | |
26 | return int (t * 1000.0 * 1000.0) | |
27 | ||
28 | class Ann: | |
29 | ANN_RAW, ANN_SOF, ANN_IFS, ANN_DATA, \ | |
30 | ANN_PACKET = range(5) | |
31 | ||
32 | class Decoder(srd.Decoder): | |
33 | api_version = 3 | |
34 | id = 'sae_j1850_vpw' | |
35 | name = 'SAE J1850 VPW' | |
36 | longname = 'SAE J1850 VPW.' | |
37 | desc = 'SAE J1850 Variable Pulse Width 1x and 4x.' | |
38 | license = 'gplv2+' | |
39 | inputs = ['logic'] | |
40 | outputs = [] | |
41 | tags = ['Automotive'] | |
42 | channels = ( | |
43 | {'id': 'data', 'name': 'Data', 'desc': 'Data line'}, | |
44 | ) | |
45 | annotations = ( | |
46 | ('raw', 'Raw'), | |
47 | ('sof', 'SOF'), | |
48 | ('ifs', 'EOF/IFS'), | |
49 | ('data', 'Data'), | |
50 | ('packet', 'Packet'), | |
51 | ) | |
52 | annotation_rows = ( | |
53 | ('raws', 'Raws', (Ann.ANN_RAW, Ann.ANN_SOF, Ann.ANN_IFS,)), | |
54 | ('bytes', 'Bytes', (Ann.ANN_DATA,)), | |
55 | ('packets', 'Packets', (Ann.ANN_PACKET,)), | |
56 | ) | |
57 | ||
58 | def __init__(self): | |
59 | self.reset() | |
60 | ||
61 | def reset(self): | |
62 | self.state = 'IDLE' | |
63 | self.samplerate = None | |
64 | self.byte = 0 # the byte offset in the packet | |
65 | self.mode = 0 # for by packet decode | |
66 | self.data = 0 # the current byte | |
67 | self.datastart = 0 # sample number this byte started at | |
68 | self.csa = 0 # track the last byte seperately to retrospectively add the CS marker | |
69 | self.csb = 0 | |
70 | self.count = 0 # which bit number we are up to | |
71 | self.active = 0 # which logic level is considered active | |
72 | ||
73 | # vpw timings. ideal, min and max tollerances. | |
74 | # From SAE J1850 1995 rev section 23.406 | |
75 | ||
76 | self.sof = 200 | |
77 | self.sofl = 164 | |
78 | self.sofh = 245 # 240 by the spec, 245 so a 60us 4x sample will pass | |
79 | self.long = 128 | |
80 | self.longl = 97 | |
81 | self.longh = 170 # 164 by the spec but 170 for low sample rate tolerance. | |
82 | self.short = 64 | |
83 | self.shortl = 24 # 35 by the spec, 24 to allow down to 6us as measured in practice for 4x @ 1mhz sampling | |
84 | self.shorth = 97 | |
85 | self.ifs = 240 | |
86 | self.spd = 1 # set to 4 when a 4x SOF is detected (VPW high speed frame) | |
87 | ||
88 | def handle_bit(self, ss, es, b): | |
89 | self.data |= (b << 7-self.count) # MSB-first | |
90 | self.put(ss, es, self.out_ann, [Ann.ANN_RAW, ["%d" % b]]) | |
91 | if self.count == 0: | |
92 | self.datastart = ss | |
93 | if self.count == 7: | |
94 | self.csa = self.datastart # for CS | |
95 | self.csb = self.samplenum # for CS | |
96 | self.put(self.datastart, self.samplenum, self.out_ann, [Ann.ANN_DATA, ["%02X" % self.data]]) | |
97 | # add protocol parsing here | |
98 | if self.byte == 0: | |
99 | self.put(self.datastart, self.samplenum, self.out_ann, [Ann.ANN_PACKET, ['Priority','Prio','P']]) | |
100 | elif self.byte == 1: | |
101 | self.put(self.datastart, self.samplenum, self.out_ann, [Ann.ANN_PACKET, ['Destination','Dest','D']]) | |
102 | elif self.byte == 2: | |
103 | self.put(self.datastart, self.samplenum, self.out_ann, [Ann.ANN_PACKET, ['Source','Src','S']]) | |
104 | elif self.byte == 3: | |
105 | self.put(self.datastart, self.samplenum, self.out_ann, [Ann.ANN_PACKET, ['Mode','M']]) | |
106 | self.mode = self.data | |
107 | elif self.mode == 1 and self.byte == 4: # mode 1 payload | |
108 | self.put(self.datastart, self.samplenum, self.out_ann, [Ann.ANN_PACKET, ['Pid','P']]) | |
109 | ||
110 | # prepare for next byte | |
111 | self.count = -1 | |
112 | self.data = 0 | |
113 | self.byte = self.byte + 1 # track packet offset | |
114 | self.count = self.count + 1 | |
115 | ||
116 | def metadata(self, key, value): | |
117 | if key == srd.SRD_CONF_SAMPLERATE: | |
118 | self.samplerate = value | |
119 | ||
120 | def start(self): | |
121 | self.out_ann = self.register(srd.OUTPUT_ANN) | |
122 | ||
123 | def decode(self): | |
124 | if not self.samplerate: | |
125 | raise SamplerateError('Cannot decode without samplerate.') | |
126 | ||
127 | self.wait({0: 'e'}) | |
128 | es = self.samplenum | |
129 | while True: | |
130 | ss = es | |
131 | pin, = self.wait({0: 'e'}) | |
132 | es = self.samplenum | |
133 | ||
134 | samples = es - ss | |
135 | t = timeuf(samples / self.samplerate) | |
136 | if self.state == 'IDLE': # detect and set speed from the size of sof | |
137 | if pin == self.active and t in range(self.sofl , self.sofh): | |
138 | self.put(ss, es, self.out_ann, [Ann.ANN_RAW, ['1X SOF', 'S1', 'S']]) | |
139 | self.spd = 1 | |
140 | self.data = 0 | |
141 | self.count = 0 | |
142 | self.state = 'DATA' | |
143 | elif pin == self.active and t in range(int(self.sofl / 4) , int(self.sofh / 4)): | |
144 | self.put(ss, es, self.out_ann, [Ann.ANN_RAW, ['4X SOF', 'S4', '4']]) | |
145 | self.spd = 4 | |
146 | self.data = 0 | |
147 | self.count = 0 | |
148 | self.state = 'DATA' | |
149 | ||
150 | elif self.state == 'DATA': | |
151 | if t >= int(self.ifs / self.spd): | |
152 | self.state = 'IDLE' | |
153 | self.put(ss, es, self.out_ann, [Ann.ANN_RAW, ["EOF/IFS", "E"]]) # EOF=239-280 IFS=281+ | |
154 | self.put(self.csa, self.csb, self.out_ann, [Ann.ANN_PACKET, ['Checksum','CS','C']]) # retrospective print of CS | |
155 | self.byte = 0 # reset packet offset | |
156 | elif t in range(int(self.shortl / self.spd), int(self.shorth / self.spd)): | |
157 | if pin == self.active: | |
158 | self.handle_bit(ss, es, 1) | |
159 | else: | |
160 | self.handle_bit(ss, es, 0) | |
161 | elif t in range(int(self.longl / self.spd), int(self.longh / self.spd)): | |
162 | if pin == self.active: | |
163 | self.handle_bit(ss, es, 0) | |
164 | else: | |
165 | self.handle_bit(ss, es, 1) |