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1 | ## | |
2 | ## This file is part of the libsigrokdecode project. | |
3 | ## | |
4 | ## Copyright (C) 2019-2020 Philip Ã…kesson <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 | ||
20 | from common.srdhelper import bitpack | |
21 | import sigrokdecode as srd | |
22 | ||
23 | class SamplerateError(Exception): | |
24 | pass | |
25 | ||
26 | class Pin: | |
27 | SDQ, = range(1) | |
28 | ||
29 | class Ann: | |
30 | BIT, BYTE, BREAK, = range(3) | |
31 | ||
32 | class Decoder(srd.Decoder): | |
33 | api_version = 3 | |
34 | id = 'sdq' | |
35 | name = 'SDQ' | |
36 | longname = 'Texas Instruments SDQ' | |
37 | desc = 'Texas Instruments SDQ. The SDQ protocol is also used by Apple.' | |
38 | license = 'gplv2+' | |
39 | inputs = ['logic'] | |
40 | outputs = [] | |
41 | tags = ['Embedded/industrial'] | |
42 | channels = ( | |
43 | {'id': 'sdq', 'name': 'SDQ', 'desc': 'Single wire SDQ data line.'}, | |
44 | ) | |
45 | options = ( | |
46 | {'id': 'bitrate', 'desc': 'Bit rate', 'default': 98425}, | |
47 | ) | |
48 | annotations = ( | |
49 | ('bit', 'Bit'), | |
50 | ('byte', 'Byte'), | |
51 | ('break', 'Break'), | |
52 | ) | |
53 | annotation_rows = ( | |
54 | ('bits', 'Bits', (Ann.BIT,)), | |
55 | ('bytes', 'Bytes', (Ann.BYTE,)), | |
56 | ('breaks', 'Breaks', (Ann.BREAK,)), | |
57 | ) | |
58 | ||
59 | def puts(self, data): | |
60 | self.put(self.startsample, self.samplenum, self.out_ann, data) | |
61 | ||
62 | def putetu(self, data): | |
63 | self.put(self.startsample, self.startsample + int(self.bit_width), self.out_ann, data) | |
64 | ||
65 | def putbetu(self, data): | |
66 | self.put(self.bytepos, self.startsample + int(self.bit_width), self.out_ann, data) | |
67 | ||
68 | def __init__(self): | |
69 | self.reset() | |
70 | ||
71 | def reset(self): | |
72 | self.samplerate = None | |
73 | self.startsample = 0 | |
74 | self.bits = [] | |
75 | self.bytepos = 0 | |
76 | ||
77 | def start(self): | |
78 | self.out_ann = self.register(srd.OUTPUT_ANN) | |
79 | ||
80 | def metadata(self, key, value): | |
81 | if key == srd.SRD_CONF_SAMPLERATE: | |
82 | self.samplerate = value | |
83 | ||
84 | def handle_bit(self, bit): | |
85 | self.bits.append(bit) | |
86 | self.putetu([Ann.BIT, [ | |
87 | 'Bit: {:d}'.format(bit), | |
88 | '{:d}'.format(bit), | |
89 | ]]) | |
90 | ||
91 | if len(self.bits) == 8: | |
92 | byte = bitpack(self.bits) | |
93 | self.putbetu([Ann.BYTE, [ | |
94 | 'Byte: 0x{:02x}'.format(byte), | |
95 | '0x{:02x}'.format(byte), | |
96 | ]]) | |
97 | self.bits = [] | |
98 | self.bytepos = 0 | |
99 | ||
100 | def handle_break(self): | |
101 | self.puts([Ann.BREAK, ['Break', 'BR']]) | |
102 | self.bits = [] | |
103 | self.startsample = self.samplenum | |
104 | self.bytepos = 0 | |
105 | ||
106 | def decode(self): | |
107 | if not self.samplerate: | |
108 | raise SamplerateError('Cannot decode without samplerate.') | |
109 | self.bit_width = float(self.samplerate) / float(self.options['bitrate']) | |
110 | self.half_bit_width = self.bit_width / 2.0 | |
111 | # BREAK if the line is low for longer than this. | |
112 | break_threshold = self.bit_width * 1.2 | |
113 | ||
114 | # Wait until the line is high before inspecting input data. | |
115 | sdq, = self.wait({Pin.SDQ: 'h'}) | |
116 | while True: | |
117 | # Get the length of a low pulse (falling to rising edge). | |
118 | sdq, = self.wait({Pin.SDQ: 'f'}) | |
119 | self.startsample = self.samplenum | |
120 | if self.bytepos == 0: | |
121 | self.bytepos = self.samplenum | |
122 | sdq, = self.wait({Pin.SDQ: 'r'}) | |
123 | ||
124 | # Check for 0 or 1 data bits, or the BREAK symbol. | |
125 | delta = self.samplenum - self.startsample | |
126 | if delta > break_threshold: | |
127 | self.handle_break() | |
128 | elif delta > self.half_bit_width: | |
129 | self.handle_bit(0) | |
130 | else: | |
131 | self.handle_bit(1) |