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b094e813 PÅ |
1 | ## |
2 | ## This file is part of the libsigrokdecode project. | |
3 | ## | |
4 | ## Copyright (C) 2019-2020 Philip Åkesson <philip.akesson@gmail.com> | |
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 | ||
2bb149e6 | 20 | from common.srdhelper import bitpack |
b094e813 PÅ |
21 | import sigrokdecode as srd |
22 | ||
23 | class SamplerateError(Exception): | |
24 | pass | |
25 | ||
26 | class Decoder(srd.Decoder): | |
27 | api_version = 3 | |
28 | id = 'sdq' | |
29 | name = 'SDQ' | |
30 | longname = 'Texas Instruments SDQ' | |
31 | desc = 'Texas Instruments SDQ. The SDQ protocol is also used by Apple.' | |
32 | license = 'gplv2+' | |
33 | inputs = ['logic'] | |
34 | outputs = [] | |
35 | tags = ['Embedded/industrial'] | |
36 | channels = ( | |
37 | {'id': 'sdq', 'name': 'SDQ', 'desc': 'Single wire SDQ data line.'}, | |
38 | ) | |
39 | options = ( | |
40 | {'id': 'bitrate', 'desc': 'Bit rate', 'default': 98425}, | |
41 | ) | |
42 | annotations = ( | |
43 | ('bit', 'Bit'), | |
44 | ('byte', 'Byte'), | |
45 | ('break', 'Break'), | |
46 | ) | |
47 | annotation_rows = ( | |
48 | ('bits', 'Bits', (0,)), | |
49 | ('bytes', 'Bytes', (1,)), | |
50 | ('breaks', 'Breaks', (2,)), | |
51 | ) | |
52 | ||
53 | def puts(self, data): | |
54 | self.put(self.startsample, self.samplenum, self.out_ann, data) | |
55 | ||
56 | def putetu(self, data): | |
57 | self.put(self.startsample, self.startsample + int(self.bit_width), self.out_ann, data) | |
58 | ||
59 | def putbetu(self, data): | |
60 | self.put(self.bytepos, self.startsample + int(self.bit_width), self.out_ann, data) | |
61 | ||
b094e813 PÅ |
62 | def __init__(self): |
63 | self.reset() | |
64 | ||
65 | def reset(self): | |
66 | self.samplerate = None | |
b094e813 PÅ |
67 | self.startsample = 0 |
68 | self.bits = [] | |
69 | self.bytepos = 0 | |
70 | ||
71 | def start(self): | |
72 | self.out_ann = self.register(srd.OUTPUT_ANN) | |
73 | ||
74 | def metadata(self, key, value): | |
75 | if key == srd.SRD_CONF_SAMPLERATE: | |
76 | self.samplerate = value | |
b094e813 PÅ |
77 | |
78 | def handle_bit(self, bit): | |
79 | self.bits.append(bit) | |
80 | self.putetu([0, ['Bit: %d' % bit, '%d' % bit]]) | |
81 | ||
82 | if len(self.bits) == 8: | |
2bb149e6 | 83 | byte = bitpack(self.bits) |
b094e813 PÅ |
84 | self.putbetu([1, ['Byte: %#04x' % byte, '%#04x' % byte]]) |
85 | self.bits = [] | |
86 | self.bytepos = 0 | |
87 | ||
88 | def handle_break(self): | |
89 | self.puts([2, ['Break', 'BR']]) | |
90 | self.bits = [] | |
91 | self.startsample = self.samplenum | |
92 | self.bytepos = 0 | |
93 | ||
94 | def decode(self): | |
95 | if not self.samplerate: | |
96 | raise SamplerateError('Cannot decode without samplerate.') | |
d7c23408 GS |
97 | self.bit_width = float(self.samplerate) / float(self.options['bitrate']) |
98 | self.half_bit_width = self.bit_width / 2.0 | |
99 | # BREAK if the line is low for longer than this. | |
b6975c68 | 100 | break_threshold = self.bit_width * 1.2 |
b094e813 | 101 | |
b6975c68 GS |
102 | # Wait until the line is high before inspecting input data. |
103 | sdq, = self.wait({0: 'h'}) | |
b094e813 | 104 | while True: |
b6975c68 GS |
105 | # Get the length of a low pulse (falling to rising edge). |
106 | sdq, = self.wait({0: 'f'}) | |
107 | self.startsample = self.samplenum | |
108 | if self.bytepos == 0: | |
109 | self.bytepos = self.samplenum | |
110 | sdq, = self.wait({0: 'r'}) | |
111 | ||
112 | # Check for 0 or 1 data bits, or the BREAK symbol. | |
113 | delta = self.samplenum - self.startsample | |
114 | if delta > break_threshold: | |
b094e813 | 115 | self.handle_break() |
b6975c68 GS |
116 | elif delta > self.half_bit_width: |
117 | self.handle_bit(0) | |
118 | else: | |
119 | self.handle_bit(1) |