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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 | import sigrokdecode as srd | |
23 | ||
24 | ''' | |
25 | Protocol output format: | |
26 | ||
27 | SPI packet: | |
28 | [<cmd>, <data1>, <data2>] | |
29 | ||
30 | Commands: | |
31 | - 'DATA': <data1> contains the MISO data, <data2> contains the MOSI data. | |
32 | The data is _usually_ 8 bits (but can also be fewer or more bits). | |
33 | Both data items are Python numbers, not strings. | |
34 | - 'CS CHANGE': <data1> is the old CS# pin value, <data2> is the new value. | |
35 | Both data items are Python numbers (0/1), not strings. | |
36 | ||
37 | Examples: | |
38 | ['CS-CHANGE', 1, 0] | |
39 | ['DATA', 0xff, 0x3a] | |
40 | ['DATA', 0x65, 0x00] | |
41 | ['CS-CHANGE', 0, 1] | |
42 | ''' | |
43 | ||
44 | # Key: (CPOL, CPHA). Value: SPI mode. | |
45 | # Clock polarity (CPOL) = 0/1: Clock is low/high when inactive. | |
46 | # Clock phase (CPHA) = 0/1: Data is valid on the leading/trailing clock edge. | |
47 | spi_mode = { | |
48 | (0, 0): 0, # Mode 0 | |
49 | (0, 1): 1, # Mode 1 | |
50 | (1, 0): 2, # Mode 2 | |
51 | (1, 1): 3, # Mode 3 | |
52 | } | |
53 | ||
54 | class Decoder(srd.Decoder): | |
55 | api_version = 1 | |
56 | id = 'spi' | |
57 | name = 'SPI' | |
58 | longname = 'Serial Peripheral Interface' | |
59 | desc = 'Full-duplex, synchronous, serial bus.' | |
60 | license = 'gplv2+' | |
61 | inputs = ['logic'] | |
62 | outputs = ['spi'] | |
63 | probes = [ | |
64 | {'id': 'miso', 'name': 'MISO', | |
65 | 'desc': 'SPI MISO line (Master in, slave out)'}, | |
66 | {'id': 'mosi', 'name': 'MOSI', | |
67 | 'desc': 'SPI MOSI line (Master out, slave in)'}, | |
68 | {'id': 'sck', 'name': 'CLK', 'desc': 'SPI clock line'}, | |
69 | ] | |
70 | optional_probes = [ | |
71 | {'id': 'cs', 'name': 'CS#', 'desc': 'SPI chip-select line'}, | |
72 | ] | |
73 | options = { | |
74 | 'cs_polarity': ['CS# polarity', 'active-low'], | |
75 | 'cpol': ['Clock polarity', 0], | |
76 | 'cpha': ['Clock phase', 0], | |
77 | 'bitorder': ['Bit order within the SPI data', 'msb-first'], | |
78 | 'wordsize': ['Word size of SPI data', 8], # 1-64? | |
79 | 'format': ['Data format', 'hex'], | |
80 | } | |
81 | annotations = [ | |
82 | ['miso-data', 'MISO SPI data'], | |
83 | ['mosi-data', 'MOSI SPI data'], | |
84 | ['warnings', 'Human-readable warnings'], | |
85 | ] | |
86 | ||
87 | def __init__(self): | |
88 | self.samplerate = None | |
89 | self.oldsck = 1 | |
90 | self.bitcount = 0 | |
91 | self.mosidata = 0 | |
92 | self.misodata = 0 | |
93 | self.startsample = -1 | |
94 | self.samplenum = -1 | |
95 | self.cs_was_deasserted_during_data_word = 0 | |
96 | self.oldcs = -1 | |
97 | self.oldpins = None | |
98 | self.state = 'IDLE' | |
99 | ||
100 | def metadata(self, key, value): | |
101 | if key == srd.SRD_CONF_SAMPLERATE: | |
102 | self.samplerate = value | |
103 | ||
104 | def start(self): | |
105 | self.out_proto = self.register(srd.OUTPUT_PYTHON) | |
106 | self.out_ann = self.register(srd.OUTPUT_ANN) | |
107 | self.out_bitrate = self.register(srd.OUTPUT_META, | |
108 | meta=(int, 'Bitrate', 'Bitrate during transfers')) | |
109 | ||
110 | def putpw(self, data): | |
111 | self.put(self.startsample, self.samplenum, self.out_proto, data) | |
112 | ||
113 | def putw(self, data): | |
114 | self.put(self.startsample, self.samplenum, self.out_ann, data) | |
115 | ||
116 | def handle_bit(self, miso, mosi, sck, cs): | |
117 | # If this is the first bit, save its sample number. | |
118 | if self.bitcount == 0: | |
119 | self.startsample = self.samplenum | |
120 | if self.have_cs: | |
121 | active_low = (self.options['cs_polarity'] == 'active-low') | |
122 | deasserted = cs if active_low else not cs | |
123 | if deasserted: | |
124 | self.cs_was_deasserted_during_data_word = 1 | |
125 | ||
126 | ws = self.options['wordsize'] | |
127 | ||
128 | # Receive MOSI bit into our shift register. | |
129 | if self.options['bitorder'] == 'msb-first': | |
130 | self.mosidata |= mosi << (ws - 1 - self.bitcount) | |
131 | else: | |
132 | self.mosidata |= mosi << self.bitcount | |
133 | ||
134 | # Receive MISO bit into our shift register. | |
135 | if self.options['bitorder'] == 'msb-first': | |
136 | self.misodata |= miso << (ws - 1 - self.bitcount) | |
137 | else: | |
138 | self.misodata |= miso << self.bitcount | |
139 | ||
140 | self.bitcount += 1 | |
141 | ||
142 | # Continue to receive if not enough bits were received, yet. | |
143 | if self.bitcount != ws: | |
144 | return | |
145 | ||
146 | # Pass MOSI and MISO to the next PD up the stack | |
147 | self.putpw(['DATA', self.mosidata, self.misodata]) | |
148 | ||
149 | # Annotations | |
150 | self.putw([0, ['%02X' % self.misodata]]) | |
151 | self.putw([1, ['%02X' % self.mosidata]]) | |
152 | ||
153 | # Meta bitrate | |
154 | elapsed = 1 / float(self.samplerate) * (self.samplenum - self.startsample + 1) | |
155 | bitrate = int(1 / elapsed * self.options['wordsize']) | |
156 | self.put(self.startsample, self.samplenum, self.out_bitrate, bitrate) | |
157 | ||
158 | if self.cs_was_deasserted_during_data_word: | |
159 | self.putw([2, ['CS# was deasserted during this data word!']]) | |
160 | ||
161 | # Reset decoder state. | |
162 | self.mosidata = self.misodata = self.bitcount = 0 | |
163 | ||
164 | def find_clk_edge(self, miso, mosi, sck, cs): | |
165 | if self.have_cs and self.oldcs != cs: | |
166 | # Send all CS# pin value changes. | |
167 | self.put(self.samplenum, self.samplenum, self.out_proto, | |
168 | ['CS-CHANGE', self.oldcs, cs]) | |
169 | self.oldcs = cs | |
170 | # Reset decoder state when CS# changes (and the CS# pin is used). | |
171 | self.mosidata = self.misodata = self.bitcount= 0 | |
172 | ||
173 | # Ignore sample if the clock pin hasn't changed. | |
174 | if sck == self.oldsck: | |
175 | return | |
176 | ||
177 | self.oldsck = sck | |
178 | ||
179 | # Sample data on rising/falling clock edge (depends on mode). | |
180 | mode = spi_mode[self.options['cpol'], self.options['cpha']] | |
181 | if mode == 0 and sck == 0: # Sample on rising clock edge | |
182 | return | |
183 | elif mode == 1 and sck == 1: # Sample on falling clock edge | |
184 | return | |
185 | elif mode == 2 and sck == 1: # Sample on falling clock edge | |
186 | return | |
187 | elif mode == 3 and sck == 0: # Sample on rising clock edge | |
188 | return | |
189 | ||
190 | # Found the correct clock edge, now get the SPI bit(s). | |
191 | self.handle_bit(miso, mosi, sck, cs) | |
192 | ||
193 | def decode(self, ss, es, data): | |
194 | if self.samplerate is None: | |
195 | raise Exception("Cannot decode without samplerate.") | |
196 | # TODO: Either MISO or MOSI could be optional. CS# is optional. | |
197 | for (self.samplenum, pins) in data: | |
198 | ||
199 | # Ignore identical samples early on (for performance reasons). | |
200 | if self.oldpins == pins: | |
201 | continue | |
202 | self.oldpins, (miso, mosi, sck, cs) = pins, pins | |
203 | self.have_cs = (cs in (0, 1)) | |
204 | ||
205 | # State machine. | |
206 | if self.state == 'IDLE': | |
207 | self.find_clk_edge(miso, mosi, sck, cs) | |
208 | else: | |
209 | raise Exception('Invalid state: %s' % self.state) | |
210 |