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0588ed70 | 1 | ## |
50bd5d25 | 2 | ## This file is part of the libsigrokdecode project. |
0588ed70 | 3 | ## |
592f355b | 4 | ## Copyright (C) 2010-2016 Uwe Hermann <uwe@hermann-uwe.de> |
0588ed70 UH |
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 | |
4539e9ca | 17 | ## along with this program; if not, see <http://www.gnu.org/licenses/>. |
0588ed70 UH |
18 | ## |
19 | ||
0588ed70 | 20 | # TODO: Look into arbitration, collision detection, clock synchronisation, etc. |
9e95e4d8 | 21 | # TODO: Implement support for 10bit slave addresses. |
0588ed70 UH |
22 | # TODO: Implement support for inverting SDA/SCL levels (0->1 and 1->0). |
23 | # TODO: Implement support for detecting various bus errors. | |
23fb2e12 | 24 | |
677d597b | 25 | import sigrokdecode as srd |
b2c19614 | 26 | |
f1428c4c | 27 | ''' |
c515eed7 | 28 | OUTPUT_PYTHON format: |
f1428c4c | 29 | |
bf69977d UH |
30 | Packet: |
31 | [<ptype>, <pdata>] | |
f1428c4c | 32 | |
bf69977d | 33 | <ptype>: |
f1428c4c UH |
34 | - 'START' (START condition) |
35 | - 'START REPEAT' (Repeated START condition) | |
36 | - 'ADDRESS READ' (Slave address, read) | |
37 | - 'ADDRESS WRITE' (Slave address, write) | |
38 | - 'DATA READ' (Data, read) | |
39 | - 'DATA WRITE' (Data, write) | |
40 | - 'STOP' (STOP condition) | |
41 | - 'ACK' (ACK bit) | |
42 | - 'NACK' (NACK bit) | |
bf69977d | 43 | - 'BITS' (<pdata>: list of data/address bits and their ss/es numbers) |
f1428c4c | 44 | |
bf69977d | 45 | <pdata> is the data or address byte associated with the 'ADDRESS*' and 'DATA*' |
f1428c4c UH |
46 | command. Slave addresses do not include bit 0 (the READ/WRITE indication bit). |
47 | For example, a slave address field could be 0x51 (instead of 0xa2). | |
bf69977d | 48 | For 'START', 'START REPEAT', 'STOP', 'ACK', and 'NACK' <pdata> is None. |
f1428c4c UH |
49 | ''' |
50 | ||
d94ff143 | 51 | # CMD: [annotation-type-index, long annotation, short annotation] |
1541976f | 52 | proto = { |
d94ff143 UH |
53 | 'START': [0, 'Start', 'S'], |
54 | 'START REPEAT': [1, 'Start repeat', 'Sr'], | |
55 | 'STOP': [2, 'Stop', 'P'], | |
56 | 'ACK': [3, 'ACK', 'A'], | |
57 | 'NACK': [4, 'NACK', 'N'], | |
de038c47 UH |
58 | 'BIT': [5, 'Bit', 'B'], |
59 | 'ADDRESS READ': [6, 'Address read', 'AR'], | |
60 | 'ADDRESS WRITE': [7, 'Address write', 'AW'], | |
61 | 'DATA READ': [8, 'Data read', 'DR'], | |
62 | 'DATA WRITE': [9, 'Data write', 'DW'], | |
15969949 | 63 | } |
e5080882 | 64 | |
d2bdb130 BV |
65 | class SamplerateError(Exception): |
66 | pass | |
67 | ||
677d597b | 68 | class Decoder(srd.Decoder): |
592f355b | 69 | api_version = 3 |
67e847fd | 70 | id = 'i2c' |
ab4aa33c | 71 | name = 'I²C' |
9a12a6e7 | 72 | longname = 'Inter-Integrated Circuit' |
a465436e | 73 | desc = 'Two-wire, multi-master, serial bus.' |
f39d2404 UH |
74 | license = 'gplv2+' |
75 | inputs = ['logic'] | |
76 | outputs = ['i2c'] | |
6a15597a | 77 | channels = ( |
bc5f5a43 BV |
78 | {'id': 'scl', 'name': 'SCL', 'desc': 'Serial clock line'}, |
79 | {'id': 'sda', 'name': 'SDA', 'desc': 'Serial data line'}, | |
da9bcbd9 | 80 | ) |
84c1c0b5 BV |
81 | options = ( |
82 | {'id': 'address_format', 'desc': 'Displayed slave address format', | |
83 | 'default': 'shifted', 'values': ('shifted', 'unshifted')}, | |
84 | ) | |
da9bcbd9 BV |
85 | annotations = ( |
86 | ('start', 'Start condition'), | |
87 | ('repeat-start', 'Repeat start condition'), | |
88 | ('stop', 'Stop condition'), | |
89 | ('ack', 'ACK'), | |
90 | ('nack', 'NACK'), | |
91 | ('bit', 'Data/address bit'), | |
92 | ('address-read', 'Address read'), | |
93 | ('address-write', 'Address write'), | |
94 | ('data-read', 'Data read'), | |
95 | ('data-write', 'Data write'), | |
96 | ('warnings', 'Human-readable warnings'), | |
97 | ) | |
de038c47 UH |
98 | annotation_rows = ( |
99 | ('bits', 'Bits', (5,)), | |
100 | ('addr-data', 'Address/Data', (0, 1, 2, 3, 4, 6, 7, 8, 9)), | |
101 | ('warnings', 'Warnings', (10,)), | |
102 | ) | |
a929afa6 | 103 | binary = ( |
5cb2cb02 BV |
104 | ('address-read', 'Address read'), |
105 | ('address-write', 'Address write'), | |
106 | ('data-read', 'Data read'), | |
107 | ('data-write', 'Data write'), | |
a929afa6 | 108 | ) |
0588ed70 | 109 | |
92b7b49f | 110 | def __init__(self): |
8d2a9636 | 111 | self.samplerate = None |
486b19ce | 112 | self.ss = self.es = self.ss_byte = -1 |
f39d2404 UH |
113 | self.bitcount = 0 |
114 | self.databyte = 0 | |
115 | self.wr = -1 | |
5dd9af5b | 116 | self.is_repeat_start = 0 |
2b716038 | 117 | self.state = 'FIND START' |
8d2a9636 BV |
118 | self.pdu_start = None |
119 | self.pdu_bits = 0 | |
de038c47 | 120 | self.bits = [] |
8d2a9636 BV |
121 | |
122 | def metadata(self, key, value): | |
123 | if key == srd.SRD_CONF_SAMPLERATE: | |
124 | self.samplerate = value | |
f39d2404 | 125 | |
8915b346 | 126 | def start(self): |
c515eed7 | 127 | self.out_python = self.register(srd.OUTPUT_PYTHON) |
8d2a9636 | 128 | self.out_ann = self.register(srd.OUTPUT_ANN) |
be6733ca | 129 | self.out_binary = self.register(srd.OUTPUT_BINARY) |
8d2a9636 BV |
130 | self.out_bitrate = self.register(srd.OUTPUT_META, |
131 | meta=(int, 'Bitrate', 'Bitrate from Start bit to Stop bit')) | |
3643fc3f | 132 | |
592f355b UH |
133 | # Assume that the initial SCL/SDA pin state is high (logic 1). |
134 | # This is a good default, since both pins have pullups as per spec. | |
135 | self.initial_pins = [1, 1] | |
136 | ||
d94ff143 | 137 | def putx(self, data): |
de038c47 | 138 | self.put(self.ss, self.es, self.out_ann, data) |
d94ff143 UH |
139 | |
140 | def putp(self, data): | |
de038c47 | 141 | self.put(self.ss, self.es, self.out_python, data) |
d94ff143 | 142 | |
a929afa6 | 143 | def putb(self, data): |
de038c47 | 144 | self.put(self.ss, self.es, self.out_binary, data) |
a929afa6 | 145 | |
592f355b | 146 | def handle_start(self, pins): |
de038c47 | 147 | self.ss, self.es = self.samplenum, self.samplenum |
8d2a9636 BV |
148 | self.pdu_start = self.samplenum |
149 | self.pdu_bits = 0 | |
c4975078 | 150 | cmd = 'START REPEAT' if (self.is_repeat_start == 1) else 'START' |
d94ff143 UH |
151 | self.putp([cmd, None]) |
152 | self.putx([proto[cmd][0], proto[cmd][1:]]) | |
2b716038 | 153 | self.state = 'FIND ADDRESS' |
7b86f0bc | 154 | self.bitcount = self.databyte = 0 |
5dd9af5b | 155 | self.is_repeat_start = 1 |
7b86f0bc | 156 | self.wr = -1 |
de038c47 | 157 | self.bits = [] |
7b86f0bc | 158 | |
c4975078 | 159 | # Gather 8 bits of data plus the ACK/NACK bit. |
592f355b UH |
160 | def handle_address_or_data(self, pins): |
161 | scl, sda = pins | |
162 | self.pdu_bits += 1 | |
163 | ||
7b86f0bc UH |
164 | # Address and data are transmitted MSB-first. |
165 | self.databyte <<= 1 | |
166 | self.databyte |= sda | |
167 | ||
de038c47 | 168 | # Remember the start of the first data/address bit. |
c4975078 | 169 | if self.bitcount == 0: |
486b19ce | 170 | self.ss_byte = self.samplenum |
de038c47 UH |
171 | |
172 | # Store individual bits and their start/end samplenumbers. | |
173 | # In the list, index 0 represents the LSB (I²C transmits MSB-first). | |
174 | self.bits.insert(0, [sda, self.samplenum, self.samplenum]) | |
175 | if self.bitcount > 0: | |
176 | self.bits[1][2] = self.samplenum | |
177 | if self.bitcount == 7: | |
178 | self.bitwidth = self.bits[1][2] - self.bits[2][2] | |
179 | self.bits[0][2] += self.bitwidth | |
c4975078 | 180 | |
7b86f0bc | 181 | # Return if we haven't collected all 8 + 1 bits, yet. |
de038c47 UH |
182 | if self.bitcount < 7: |
183 | self.bitcount += 1 | |
eb7082c9 | 184 | return |
7b86f0bc | 185 | |
d94ff143 | 186 | d = self.databyte |
2b716038 | 187 | if self.state == 'FIND ADDRESS': |
7b86f0bc | 188 | # The READ/WRITE bit is only in address bytes, not data bytes. |
bf1c3f4d | 189 | self.wr = 0 if (self.databyte & 1) else 1 |
d94ff143 UH |
190 | if self.options['address_format'] == 'shifted': |
191 | d = d >> 1 | |
15969949 | 192 | |
a929afa6 | 193 | bin_class = -1 |
2b716038 | 194 | if self.state == 'FIND ADDRESS' and self.wr == 1: |
a2d2aff2 | 195 | cmd = 'ADDRESS WRITE' |
a929afa6 | 196 | bin_class = 1 |
2b716038 | 197 | elif self.state == 'FIND ADDRESS' and self.wr == 0: |
a2d2aff2 | 198 | cmd = 'ADDRESS READ' |
a929afa6 | 199 | bin_class = 0 |
2b716038 | 200 | elif self.state == 'FIND DATA' and self.wr == 1: |
a2d2aff2 | 201 | cmd = 'DATA WRITE' |
a929afa6 | 202 | bin_class = 3 |
2b716038 | 203 | elif self.state == 'FIND DATA' and self.wr == 0: |
a2d2aff2 | 204 | cmd = 'DATA READ' |
a929afa6 | 205 | bin_class = 2 |
eb7082c9 | 206 | |
486b19ce | 207 | self.ss, self.es = self.ss_byte, self.samplenum + self.bitwidth |
de038c47 UH |
208 | |
209 | self.putp(['BITS', self.bits]) | |
d94ff143 | 210 | self.putp([cmd, d]) |
de038c47 | 211 | |
2824e811 | 212 | self.putb([bin_class, bytes([d])]) |
7b86f0bc | 213 | |
de038c47 UH |
214 | for bit in self.bits: |
215 | self.put(bit[1], bit[2], self.out_ann, [5, ['%d' % bit[0]]]) | |
216 | ||
217 | if cmd.startswith('ADDRESS'): | |
218 | self.ss, self.es = self.samplenum, self.samplenum + self.bitwidth | |
219 | w = ['Write', 'Wr', 'W'] if self.wr else ['Read', 'Rd', 'R'] | |
220 | self.putx([proto[cmd][0], w]) | |
486b19ce | 221 | self.ss, self.es = self.ss_byte, self.samplenum |
de038c47 UH |
222 | |
223 | self.putx([proto[cmd][0], ['%s: %02X' % (proto[cmd][1], d), | |
224 | '%s: %02X' % (proto[cmd][2], d), '%02X' % d]]) | |
225 | ||
1b75abfd | 226 | # Done with this packet. |
1b75abfd | 227 | self.bitcount = self.databyte = 0 |
de038c47 | 228 | self.bits = [] |
2b716038 | 229 | self.state = 'FIND ACK' |
7b86f0bc | 230 | |
592f355b UH |
231 | def get_ack(self, pins): |
232 | scl, sda = pins | |
de038c47 | 233 | self.ss, self.es = self.samplenum, self.samplenum + self.bitwidth |
d94ff143 UH |
234 | cmd = 'NACK' if (sda == 1) else 'ACK' |
235 | self.putp([cmd, None]) | |
236 | self.putx([proto[cmd][0], proto[cmd][1:]]) | |
1b75abfd BV |
237 | # There could be multiple data bytes in a row, so either find |
238 | # another data byte or a STOP condition next. | |
2b716038 | 239 | self.state = 'FIND DATA' |
7b86f0bc | 240 | |
592f355b | 241 | def handle_stop(self, pins): |
8d2a9636 BV |
242 | # Meta bitrate |
243 | elapsed = 1 / float(self.samplerate) * (self.samplenum - self.pdu_start + 1) | |
244 | bitrate = int(1 / elapsed * self.pdu_bits) | |
486b19ce | 245 | self.put(self.ss_byte, self.samplenum, self.out_bitrate, bitrate) |
8d2a9636 | 246 | |
d94ff143 | 247 | cmd = 'STOP' |
de038c47 | 248 | self.ss, self.es = self.samplenum, self.samplenum |
d94ff143 UH |
249 | self.putp([cmd, None]) |
250 | self.putx([proto[cmd][0], proto[cmd][1:]]) | |
2b716038 | 251 | self.state = 'FIND START' |
5dd9af5b | 252 | self.is_repeat_start = 0 |
7b86f0bc | 253 | self.wr = -1 |
de038c47 | 254 | self.bits = [] |
7b86f0bc | 255 | |
592f355b | 256 | def decode(self): |
d2bdb130 | 257 | if not self.samplerate: |
21cda951 | 258 | raise SamplerateError('Cannot decode without samplerate.') |
2fcd7c22 | 259 | |
592f355b | 260 | self.wait({}) |
8d2a9636 | 261 | |
592f355b | 262 | while True: |
7b86f0bc | 263 | # State machine. |
2b716038 | 264 | if self.state == 'FIND START': |
592f355b UH |
265 | # Wait for a START condition (S): SCL = high, SDA = falling. |
266 | self.handle_start(self.wait({0: 'h', 1: 'f'})) | |
2b716038 | 267 | elif self.state == 'FIND ADDRESS': |
592f355b UH |
268 | # Wait for a data bit: SCL = rising. |
269 | self.handle_address_or_data(self.wait({0: 'r'})) | |
2b716038 | 270 | elif self.state == 'FIND DATA': |
592f355b UH |
271 | # Wait for any of the following conditions (or combinations): |
272 | # a) Data sampling of receiver: SCL = rising, and/or | |
273 | # b) START condition (S): SCL = high, SDA = falling, and/or | |
274 | # c) STOP condition (P): SCL = high, SDA = rising | |
fcd5d23a | 275 | pins = self.wait([{0: 'r'}, {0: 'h', 1: 'f'}, {0: 'h', 1: 'r'}]) |
592f355b UH |
276 | |
277 | # Check which of the condition(s) matched and handle them. | |
278 | if self.matched[0]: | |
279 | self.handle_address_or_data(pins) | |
280 | elif self.matched[1]: | |
281 | self.handle_start(pins) | |
282 | elif self.matched[2]: | |
283 | self.handle_stop(pins) | |
2b716038 | 284 | elif self.state == 'FIND ACK': |
592f355b UH |
285 | # Wait for a data/ack bit: SCL = rising. |
286 | self.get_ack(self.wait({0: 'r'})) |