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1 | ## | |
2 | ## This file is part of the libsigrokdecode project. | |
3 | ## | |
4 | ## Copyright (C) 2011 Gareth McMullin <gareth@blacksphere.co.nz> | |
5 | ## Copyright (C) 2012-2013 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 | # SPI protocol decoder | |
23 | ||
24 | import sigrokdecode as srd | |
25 | ||
26 | # Key: (CPOL, CPHA). Value: SPI mode. | |
27 | # Clock polarity (CPOL) = 0/1: Clock is low/high when inactive. | |
28 | # Clock phase (CPHA) = 0/1: Data is valid on the leading/trailing clock edge. | |
29 | spi_mode = { | |
30 | (0, 0): 0, # Mode 0 | |
31 | (0, 1): 1, # Mode 1 | |
32 | (1, 0): 2, # Mode 2 | |
33 | (1, 1): 3, # Mode 3 | |
34 | } | |
35 | ||
36 | class Decoder(srd.Decoder): | |
37 | api_version = 1 | |
38 | id = 'spi' | |
39 | name = 'SPI' | |
40 | longname = 'Serial Peripheral Interface' | |
41 | desc = 'Full-duplex, synchronous, serial bus.' | |
42 | license = 'gplv2+' | |
43 | inputs = ['logic'] | |
44 | outputs = ['spi'] | |
45 | probes = [ | |
46 | {'id': 'miso', 'name': 'MISO', | |
47 | 'desc': 'SPI MISO line (Master in, slave out)'}, | |
48 | {'id': 'mosi', 'name': 'MOSI', | |
49 | 'desc': 'SPI MOSI line (Master out, slave in)'}, | |
50 | {'id': 'sck', 'name': 'CLK', 'desc': 'SPI clock line'}, | |
51 | ] | |
52 | optional_probes = [ | |
53 | {'id': 'cs', 'name': 'CS#', 'desc': 'SPI chip-select line'}, | |
54 | ] | |
55 | options = { | |
56 | 'cs_polarity': ['CS# polarity', 'active-low'], | |
57 | 'cpol': ['Clock polarity', 0], | |
58 | 'cpha': ['Clock phase', 0], | |
59 | 'bitorder': ['Bit order within the SPI data', 'msb-first'], | |
60 | 'wordsize': ['Word size of SPI data', 8], # 1-64? | |
61 | 'format': ['Data format', 'hex'], | |
62 | } | |
63 | annotations = [ | |
64 | ['MISO/MOSI data', 'MISO/MOSI SPI data'], | |
65 | ['MISO data', 'MISO SPI data'], | |
66 | ['MOSI data', 'MOSI SPI data'], | |
67 | ['Warnings', 'Human-readable warnings'], | |
68 | ] | |
69 | ||
70 | def __init__(self): | |
71 | self.oldsck = 1 | |
72 | self.bitcount = 0 | |
73 | self.mosidata = 0 | |
74 | self.misodata = 0 | |
75 | self.bytesreceived = 0 | |
76 | self.startsample = -1 | |
77 | self.samplenum = -1 | |
78 | self.cs_was_deasserted_during_data_word = 0 | |
79 | self.oldcs = -1 | |
80 | self.oldpins = None | |
81 | self.state = 'IDLE' | |
82 | ||
83 | def start(self, metadata): | |
84 | self.out_proto = self.add(srd.OUTPUT_PROTO, 'spi') | |
85 | self.out_ann = self.add(srd.OUTPUT_ANN, 'spi') | |
86 | ||
87 | def report(self): | |
88 | return 'SPI: %d bytes received' % self.bytesreceived | |
89 | ||
90 | def putpw(self, data): | |
91 | self.put(self.startsample, self.samplenum, self.out_proto, data) | |
92 | ||
93 | def putw(self, data): | |
94 | self.put(self.startsample, self.samplenum, self.out_ann, data) | |
95 | ||
96 | def handle_bit(self, miso, mosi, sck, cs): | |
97 | # If this is the first bit, save its sample number. | |
98 | if self.bitcount == 0: | |
99 | self.startsample = self.samplenum | |
100 | if self.have_cs: | |
101 | active_low = (self.options['cs_polarity'] == 'active-low') | |
102 | deasserted = cs if active_low else not cs | |
103 | if deasserted: | |
104 | self.cs_was_deasserted_during_data_word = 1 | |
105 | ||
106 | ws = self.options['wordsize'] | |
107 | ||
108 | # Receive MOSI bit into our shift register. | |
109 | if self.options['bitorder'] == 'msb-first': | |
110 | self.mosidata |= mosi << (ws - 1 - self.bitcount) | |
111 | else: | |
112 | self.mosidata |= mosi << self.bitcount | |
113 | ||
114 | # Receive MISO bit into our shift register. | |
115 | if self.options['bitorder'] == 'msb-first': | |
116 | self.misodata |= miso << (ws - 1 - self.bitcount) | |
117 | else: | |
118 | self.misodata |= miso << self.bitcount | |
119 | ||
120 | self.bitcount += 1 | |
121 | ||
122 | # Continue to receive if not enough bits were received, yet. | |
123 | if self.bitcount != ws: | |
124 | return | |
125 | ||
126 | self.putpw(['DATA', self.mosidata, self.misodata]) | |
127 | self.putw([0, ['%02X/%02X' % (self.mosidata, self.misodata)]]) | |
128 | self.putw([1, ['%02X' % self.misodata]]) | |
129 | self.putw([2, ['%02X' % self.mosidata]]) | |
130 | ||
131 | if self.cs_was_deasserted_during_data_word: | |
132 | self.putw([3, ['CS# was deasserted during this data word!']]) | |
133 | ||
134 | # Reset decoder state. | |
135 | self.mosidata = self.misodata = self.bitcount = 0 | |
136 | ||
137 | # Keep stats for summary. | |
138 | self.bytesreceived += 1 | |
139 | ||
140 | def find_clk_edge(self, miso, mosi, sck, cs): | |
141 | if self.have_cs and self.oldcs != cs: | |
142 | # Send all CS# pin value changes. | |
143 | self.put(self.samplenum, self.samplenum, self.out_proto, | |
144 | ['CS-CHANGE', self.oldcs, cs]) | |
145 | self.oldcs = cs | |
146 | # Reset decoder state when CS# changes (and the CS# pin is used). | |
147 | self.mosidata = self.misodata = self.bitcount= 0 | |
148 | ||
149 | # Ignore sample if the clock pin hasn't changed. | |
150 | if sck == self.oldsck: | |
151 | return | |
152 | ||
153 | self.oldsck = sck | |
154 | ||
155 | # Sample data on rising/falling clock edge (depends on mode). | |
156 | mode = spi_mode[self.options['cpol'], self.options['cpha']] | |
157 | if mode == 0 and sck == 0: # Sample on rising clock edge | |
158 | return | |
159 | elif mode == 1 and sck == 1: # Sample on falling clock edge | |
160 | return | |
161 | elif mode == 2 and sck == 1: # Sample on falling clock edge | |
162 | return | |
163 | elif mode == 3 and sck == 0: # Sample on rising clock edge | |
164 | return | |
165 | ||
166 | # Found the correct clock edge, now get the SPI bit(s). | |
167 | self.handle_bit(miso, mosi, sck, cs) | |
168 | ||
169 | def decode(self, ss, es, data): | |
170 | # TODO: Either MISO or MOSI could be optional. CS# is optional. | |
171 | for (self.samplenum, pins) in data: | |
172 | ||
173 | # Ignore identical samples early on (for performance reasons). | |
174 | if self.oldpins == pins: | |
175 | continue | |
176 | self.oldpins, (miso, mosi, sck, cs) = pins, pins | |
177 | self.have_cs = (cs in (0, 1)) | |
178 | ||
179 | # State machine. | |
180 | if self.state == 'IDLE': | |
181 | self.find_clk_edge(miso, mosi, sck, cs) | |
182 | else: | |
183 | raise Exception('Invalid state: %s' % self.state) | |
184 |