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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) 2012-2014 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), or None if the respective | |
34 | probe was not supplied. | |
35 | - 'CS CHANGE': <data1> is the old CS# pin value, <data2> is the new value. | |
36 | Both data items are Python numbers (0/1), not strings. | |
37 | ||
38 | Examples: | |
39 | ['CS-CHANGE', 1, 0] | |
40 | ['DATA', 0xff, 0x3a] | |
41 | ['DATA', 0x65, 0x00] | |
42 | ['DATA', 0xa8, None] | |
43 | ['DATA', None, 0x55] | |
44 | ['CS-CHANGE', 0, 1] | |
45 | ''' | |
46 | ||
47 | # Key: (CPOL, CPHA). Value: SPI mode. | |
48 | # Clock polarity (CPOL) = 0/1: Clock is low/high when inactive. | |
49 | # Clock phase (CPHA) = 0/1: Data is valid on the leading/trailing clock edge. | |
50 | spi_mode = { | |
51 | (0, 0): 0, # Mode 0 | |
52 | (0, 1): 1, # Mode 1 | |
53 | (1, 0): 2, # Mode 2 | |
54 | (1, 1): 3, # Mode 3 | |
55 | } | |
56 | ||
57 | class Decoder(srd.Decoder): | |
58 | api_version = 1 | |
59 | id = 'spi' | |
60 | name = 'SPI' | |
61 | longname = 'Serial Peripheral Interface' | |
62 | desc = 'Full-duplex, synchronous, serial bus.' | |
63 | license = 'gplv2+' | |
64 | inputs = ['logic'] | |
65 | outputs = ['spi'] | |
66 | probes = [ | |
67 | {'id': 'clk', 'name': 'CLK', 'desc': 'SPI clock line'}, | |
68 | ] | |
69 | optional_probes = [ | |
70 | {'id': 'miso', 'name': 'MISO', | |
71 | 'desc': 'SPI MISO line (master in, slave out)'}, | |
72 | {'id': 'mosi', 'name': 'MOSI', | |
73 | 'desc': 'SPI MOSI line (master out, slave in)'}, | |
74 | {'id': 'cs', 'name': 'CS#', 'desc': 'SPI chip-select line'}, | |
75 | ] | |
76 | options = { | |
77 | 'cs_polarity': ['CS# polarity', 'active-low'], | |
78 | 'cpol': ['Clock polarity', 0], | |
79 | 'cpha': ['Clock phase', 0], | |
80 | 'bitorder': ['Bit order within the SPI data', 'msb-first'], | |
81 | 'wordsize': ['Word size of SPI data', 8], # 1-64? | |
82 | 'format': ['Data format', 'hex'], | |
83 | } | |
84 | annotations = [ | |
85 | ['miso-data', 'MISO SPI data'], | |
86 | ['mosi-data', 'MOSI SPI data'], | |
87 | ['warnings', 'Human-readable warnings'], | |
88 | ] | |
89 | ||
90 | def __init__(self): | |
91 | self.samplerate = None | |
92 | self.oldclk = 1 | |
93 | self.bitcount = 0 | |
94 | self.mosidata = 0 | |
95 | self.misodata = 0 | |
96 | self.startsample = -1 | |
97 | self.samplenum = -1 | |
98 | self.cs_was_deasserted_during_data_word = 0 | |
99 | self.oldcs = -1 | |
100 | self.oldpins = None | |
101 | self.have_cs = None | |
102 | self.have_miso = None | |
103 | self.have_mosi = None | |
104 | self.state = 'IDLE' | |
105 | ||
106 | def metadata(self, key, value): | |
107 | if key == srd.SRD_CONF_SAMPLERATE: | |
108 | self.samplerate = value | |
109 | ||
110 | def start(self): | |
111 | self.out_proto = self.register(srd.OUTPUT_PYTHON) | |
112 | self.out_ann = self.register(srd.OUTPUT_ANN) | |
113 | self.out_bitrate = self.register(srd.OUTPUT_META, | |
114 | meta=(int, 'Bitrate', 'Bitrate during transfers')) | |
115 | ||
116 | def putpw(self, data): | |
117 | self.put(self.startsample, self.samplenum, self.out_proto, data) | |
118 | ||
119 | def putw(self, data): | |
120 | self.put(self.startsample, self.samplenum, self.out_ann, data) | |
121 | ||
122 | def handle_bit(self, miso, mosi, clk, cs): | |
123 | # If this is the first bit, save its sample number. | |
124 | if self.bitcount == 0: | |
125 | self.startsample = self.samplenum | |
126 | if self.have_cs: | |
127 | active_low = (self.options['cs_polarity'] == 'active-low') | |
128 | deasserted = cs if active_low else not cs | |
129 | if deasserted: | |
130 | self.cs_was_deasserted_during_data_word = 1 | |
131 | ||
132 | ws = self.options['wordsize'] | |
133 | ||
134 | # Receive MOSI bit into our shift register. | |
135 | if self.have_mosi: | |
136 | if self.options['bitorder'] == 'msb-first': | |
137 | self.mosidata |= mosi << (ws - 1 - self.bitcount) | |
138 | else: | |
139 | self.mosidata |= mosi << self.bitcount | |
140 | ||
141 | # Receive MISO bit into our shift register. | |
142 | if self.have_miso: | |
143 | if self.options['bitorder'] == 'msb-first': | |
144 | self.misodata |= miso << (ws - 1 - self.bitcount) | |
145 | else: | |
146 | self.misodata |= miso << self.bitcount | |
147 | ||
148 | self.bitcount += 1 | |
149 | ||
150 | # Continue to receive if not enough bits were received, yet. | |
151 | if self.bitcount != ws: | |
152 | return | |
153 | ||
154 | si = self.mosidata if self.have_mosi else None | |
155 | so = self.misodata if self.have_miso else None | |
156 | ||
157 | # Pass MOSI and MISO to the next PD up the stack. | |
158 | self.putpw(['DATA', si, so]) | |
159 | ||
160 | # Annotations. | |
161 | if self.have_miso: | |
162 | self.putw([0, ['%02X' % self.misodata]]) | |
163 | if self.have_mosi: | |
164 | self.putw([1, ['%02X' % self.mosidata]]) | |
165 | ||
166 | # Meta bitrate. | |
167 | elapsed = 1 / float(self.samplerate) * (self.samplenum - self.startsample + 1) | |
168 | bitrate = int(1 / elapsed * self.options['wordsize']) | |
169 | self.put(self.startsample, self.samplenum, self.out_bitrate, bitrate) | |
170 | ||
171 | if self.have_cs and self.cs_was_deasserted_during_data_word: | |
172 | self.putw([2, ['CS# was deasserted during this data word!']]) | |
173 | ||
174 | # Reset decoder state. | |
175 | self.misodata = 0 if self.have_miso else None | |
176 | self.mosidata = 0 if self.have_mosi else None | |
177 | self.bitcount = 0 | |
178 | ||
179 | def find_clk_edge(self, miso, mosi, clk, cs): | |
180 | if self.have_cs and self.oldcs != cs: | |
181 | # Send all CS# pin value changes. | |
182 | self.put(self.samplenum, self.samplenum, self.out_proto, | |
183 | ['CS-CHANGE', self.oldcs, cs]) | |
184 | self.oldcs = cs | |
185 | # Reset decoder state when CS# changes (and the CS# pin is used). | |
186 | self.misodata = 0 if self.have_miso else None | |
187 | self.mosidata = 0 if self.have_mosi else None | |
188 | self.bitcount = 0 | |
189 | ||
190 | # Ignore sample if the clock pin hasn't changed. | |
191 | if clk == self.oldclk: | |
192 | return | |
193 | ||
194 | self.oldclk = clk | |
195 | ||
196 | # Sample data on rising/falling clock edge (depends on mode). | |
197 | mode = spi_mode[self.options['cpol'], self.options['cpha']] | |
198 | if mode == 0 and clk == 0: # Sample on rising clock edge | |
199 | return | |
200 | elif mode == 1 and clk == 1: # Sample on falling clock edge | |
201 | return | |
202 | elif mode == 2 and clk == 1: # Sample on falling clock edge | |
203 | return | |
204 | elif mode == 3 and clk == 0: # Sample on rising clock edge | |
205 | return | |
206 | ||
207 | # Found the correct clock edge, now get the SPI bit(s). | |
208 | self.handle_bit(miso, mosi, clk, cs) | |
209 | ||
210 | def decode(self, ss, es, data): | |
211 | if self.samplerate is None: | |
212 | raise Exception("Cannot decode without samplerate.") | |
213 | # Either MISO or MOSI can be omitted (but not both). CS# is optional. | |
214 | for (self.samplenum, pins) in data: | |
215 | ||
216 | # Ignore identical samples early on (for performance reasons). | |
217 | if self.oldpins == pins: | |
218 | continue | |
219 | self.oldpins, (clk, miso, mosi, cs) = pins, pins | |
220 | self.have_miso = (miso in (0, 1)) | |
221 | self.have_mosi = (mosi in (0, 1)) | |
222 | self.have_cs = (cs in (0, 1)) | |
223 | ||
224 | # State machine. | |
225 | if self.state == 'IDLE': | |
226 | self.find_clk_edge(miso, mosi, clk, cs) | |
227 | else: | |
228 | raise Exception('Invalid state: %s' % self.state) | |
229 |