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1 | ## | |
2 | ## This file is part of the libsigrokdecode project. | |
3 | ## | |
4 | ## Copyright (C) 2011-2013 Uwe Hermann <uwe@hermann-uwe.de> | |
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, write to the Free Software | |
18 | ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA | |
19 | ## | |
20 | ||
21 | # UART protocol decoder | |
22 | ||
23 | import sigrokdecode as srd | |
24 | ||
25 | # Used for differentiating between the two data directions. | |
26 | RX = 0 | |
27 | TX = 1 | |
28 | ||
29 | # Given a parity type to check (odd, even, zero, one), the value of the | |
30 | # parity bit, the value of the data, and the length of the data (5-9 bits, | |
31 | # usually 8 bits) return True if the parity is correct, False otherwise. | |
32 | # 'none' is _not_ allowed as value for 'parity_type'. | |
33 | def parity_ok(parity_type, parity_bit, data, num_data_bits): | |
34 | ||
35 | # Handle easy cases first (parity bit is always 1 or 0). | |
36 | if parity_type == 'zero': | |
37 | return parity_bit == 0 | |
38 | elif parity_type == 'one': | |
39 | return parity_bit == 1 | |
40 | ||
41 | # Count number of 1 (high) bits in the data (and the parity bit itself!). | |
42 | ones = bin(data).count('1') + parity_bit | |
43 | ||
44 | # Check for odd/even parity. | |
45 | if parity_type == 'odd': | |
46 | return (ones % 2) == 1 | |
47 | elif parity_type == 'even': | |
48 | return (ones % 2) == 0 | |
49 | else: | |
50 | raise Exception('Invalid parity type: %d' % parity_type) | |
51 | ||
52 | class Decoder(srd.Decoder): | |
53 | api_version = 1 | |
54 | id = 'uart' | |
55 | name = 'UART' | |
56 | longname = 'Universal Asynchronous Receiver/Transmitter' | |
57 | desc = 'Asynchronous, serial bus.' | |
58 | license = 'gplv2+' | |
59 | inputs = ['logic'] | |
60 | outputs = ['uart'] | |
61 | probes = [ | |
62 | # Allow specifying only one of the signals, e.g. if only one data | |
63 | # direction exists (or is relevant). | |
64 | {'id': 'rx', 'name': 'RX', 'desc': 'UART receive line'}, | |
65 | {'id': 'tx', 'name': 'TX', 'desc': 'UART transmit line'}, | |
66 | ] | |
67 | optional_probes = [] | |
68 | options = { | |
69 | 'baudrate': ['Baud rate', 115200], | |
70 | 'num_data_bits': ['Data bits', 8], # Valid: 5-9. | |
71 | 'parity_type': ['Parity type', 'none'], | |
72 | 'parity_check': ['Check parity?', 'yes'], # TODO: Bool supported? | |
73 | 'num_stop_bits': ['Stop bit(s)', '1'], # String! 0, 0.5, 1, 1.5. | |
74 | 'bit_order': ['Bit order', 'lsb-first'], | |
75 | 'format': ['Data format', 'ascii'], # ascii/dec/hex/oct/bin | |
76 | # TODO: Options to invert the signal(s). | |
77 | } | |
78 | annotations = [ | |
79 | ['Data', 'UART data'], | |
80 | ] | |
81 | ||
82 | def putx(self, rxtx, data): | |
83 | s, halfbit = self.startsample[rxtx], int(self.bit_width / 2) | |
84 | self.put(s - halfbit, self.samplenum + halfbit, self.out_ann, data) | |
85 | ||
86 | def putg(self, data): | |
87 | s, halfbit = self.samplenum, int(self.bit_width / 2) | |
88 | self.put(s - halfbit, s + halfbit, self.out_ann, data) | |
89 | ||
90 | def putp(self, data): | |
91 | s, halfbit = self.samplenum, int(self.bit_width / 2) | |
92 | self.put(s - halfbit, s + halfbit, self.out_proto, data) | |
93 | ||
94 | def __init__(self, **kwargs): | |
95 | self.samplenum = 0 | |
96 | self.frame_start = [-1, -1] | |
97 | self.startbit = [-1, -1] | |
98 | self.cur_data_bit = [0, 0] | |
99 | self.databyte = [0, 0] | |
100 | self.paritybit = [-1, -1] | |
101 | self.stopbit1 = [-1, -1] | |
102 | self.startsample = [-1, -1] | |
103 | self.state = ['WAIT FOR START BIT', 'WAIT FOR START BIT'] | |
104 | self.oldbit = [1, 1] | |
105 | self.oldpins = [1, 1] | |
106 | ||
107 | def start(self, metadata): | |
108 | self.samplerate = metadata['samplerate'] | |
109 | self.out_proto = self.add(srd.OUTPUT_PROTO, 'uart') | |
110 | self.out_ann = self.add(srd.OUTPUT_ANN, 'uart') | |
111 | ||
112 | # The width of one UART bit in number of samples. | |
113 | self.bit_width = \ | |
114 | float(self.samplerate) / float(self.options['baudrate']) | |
115 | ||
116 | def report(self): | |
117 | pass | |
118 | ||
119 | # Return true if we reached the middle of the desired bit, false otherwise. | |
120 | def reached_bit(self, rxtx, bitnum): | |
121 | # bitpos is the samplenumber which is in the middle of the | |
122 | # specified UART bit (0 = start bit, 1..x = data, x+1 = parity bit | |
123 | # (if used) or the first stop bit, and so on). | |
124 | bitpos = self.frame_start[rxtx] + (self.bit_width / 2.0) | |
125 | bitpos += bitnum * self.bit_width | |
126 | if self.samplenum >= bitpos: | |
127 | return True | |
128 | return False | |
129 | ||
130 | def reached_bit_last(self, rxtx, bitnum): | |
131 | bitpos = self.frame_start[rxtx] + ((bitnum + 1) * self.bit_width) | |
132 | if self.samplenum >= bitpos: | |
133 | return True | |
134 | return False | |
135 | ||
136 | def wait_for_start_bit(self, rxtx, old_signal, signal): | |
137 | # The start bit is always 0 (low). As the idle UART (and the stop bit) | |
138 | # level is 1 (high), the beginning of a start bit is a falling edge. | |
139 | if not (old_signal == 1 and signal == 0): | |
140 | return | |
141 | ||
142 | # Save the sample number where the start bit begins. | |
143 | self.frame_start[rxtx] = self.samplenum | |
144 | ||
145 | self.state[rxtx] = 'GET START BIT' | |
146 | ||
147 | def get_start_bit(self, rxtx, signal): | |
148 | # Skip samples until we're in the middle of the start bit. | |
149 | if not self.reached_bit(rxtx, 0): | |
150 | return | |
151 | ||
152 | self.startbit[rxtx] = signal | |
153 | ||
154 | # The startbit must be 0. If not, we report an error. | |
155 | if self.startbit[rxtx] != 0: | |
156 | self.putp(['INVALID STARTBIT', rxtx, self.startbit[rxtx]]) | |
157 | # TODO: Abort? Ignore rest of the frame? | |
158 | ||
159 | self.cur_data_bit[rxtx] = 0 | |
160 | self.databyte[rxtx] = 0 | |
161 | self.startsample[rxtx] = -1 | |
162 | ||
163 | self.state[rxtx] = 'GET DATA BITS' | |
164 | ||
165 | self.putp(['STARTBIT', rxtx, self.startbit[rxtx]]) | |
166 | self.putg([0, ['Start bit', 'Start', 'S']]) | |
167 | ||
168 | def get_data_bits(self, rxtx, signal): | |
169 | # Skip samples until we're in the middle of the desired data bit. | |
170 | if not self.reached_bit(rxtx, self.cur_data_bit[rxtx] + 1): | |
171 | return | |
172 | ||
173 | # Save the sample number of the middle of the first data bit. | |
174 | if self.startsample[rxtx] == -1: | |
175 | self.startsample[rxtx] = self.samplenum | |
176 | ||
177 | # Get the next data bit in LSB-first or MSB-first fashion. | |
178 | if self.options['bit_order'] == 'lsb-first': | |
179 | self.databyte[rxtx] >>= 1 | |
180 | self.databyte[rxtx] |= \ | |
181 | (signal << (self.options['num_data_bits'] - 1)) | |
182 | elif self.options['bit_order'] == 'msb-first': | |
183 | self.databyte[rxtx] <<= 1 | |
184 | self.databyte[rxtx] |= (signal << 0) | |
185 | else: | |
186 | raise Exception('Invalid bit order value: %s', | |
187 | self.options['bit_order']) | |
188 | ||
189 | # Return here, unless we already received all data bits. | |
190 | if self.cur_data_bit[rxtx] < self.options['num_data_bits'] - 1: | |
191 | self.cur_data_bit[rxtx] += 1 | |
192 | return | |
193 | ||
194 | self.state[rxtx] = 'GET PARITY BIT' | |
195 | ||
196 | self.putp(['DATA', rxtx, self.databyte[rxtx]]) | |
197 | ||
198 | s = 'RX: ' if (rxtx == RX) else 'TX: ' | |
199 | b, f = self.databyte[rxtx], self.options['format'] | |
200 | if f == 'ascii': | |
201 | self.putx(rxtx, [0, [s + chr(b)]]) | |
202 | elif f == 'dec': | |
203 | self.putx(rxtx, [0, [s + str(b)]]) | |
204 | elif f == 'hex': | |
205 | self.putx(rxtx, [0, [s + hex(b)[2:]]]) | |
206 | elif f == 'oct': | |
207 | self.putx(rxtx, [0, [s + oct(b)[2:]]]) | |
208 | elif f == 'bin': | |
209 | self.putx(rxtx, [0, [s + bin(b)[2:]]]) | |
210 | else: | |
211 | raise Exception('Invalid data format option: %s' % f) | |
212 | ||
213 | def get_parity_bit(self, rxtx, signal): | |
214 | # If no parity is used/configured, skip to the next state immediately. | |
215 | if self.options['parity_type'] == 'none': | |
216 | self.state[rxtx] = 'GET STOP BITS' | |
217 | return | |
218 | ||
219 | # Skip samples until we're in the middle of the parity bit. | |
220 | if not self.reached_bit(rxtx, self.options['num_data_bits'] + 1): | |
221 | return | |
222 | ||
223 | self.paritybit[rxtx] = signal | |
224 | ||
225 | self.state[rxtx] = 'GET STOP BITS' | |
226 | ||
227 | if parity_ok(self.options['parity_type'], self.paritybit[rxtx], | |
228 | self.databyte[rxtx], self.options['num_data_bits']): | |
229 | self.putp(['PARITYBIT', rxtx, self.paritybit[rxtx]]) | |
230 | self.putg([0, ['Parity bit', 'Parity', 'P']]) | |
231 | else: | |
232 | # TODO: Return expected/actual parity values. | |
233 | self.putp(['PARITY ERROR', rxtx, (0, 1)]) # FIXME: Dummy tuple... | |
234 | self.putg([0, ['Parity error', 'Parity err', 'PE']]) | |
235 | ||
236 | # TODO: Currently only supports 1 stop bit. | |
237 | def get_stop_bits(self, rxtx, signal): | |
238 | # Skip samples until we're in the middle of the stop bit(s). | |
239 | skip_parity = 0 if self.options['parity_type'] == 'none' else 1 | |
240 | b = self.options['num_data_bits'] + 1 + skip_parity | |
241 | if not self.reached_bit(rxtx, b): | |
242 | return | |
243 | ||
244 | self.stopbit1[rxtx] = signal | |
245 | ||
246 | # Stop bits must be 1. If not, we report an error. | |
247 | if self.stopbit1[rxtx] != 1: | |
248 | self.putp(['INVALID STOPBIT', rxtx, self.stopbit1[rxtx]]) | |
249 | # TODO: Abort? Ignore the frame? Other? | |
250 | ||
251 | self.state[rxtx] = 'WAIT FOR START BIT' | |
252 | ||
253 | self.putp(['STOPBIT', rxtx, self.stopbit1[rxtx]]) | |
254 | self.putg([0, ['Stop bit', 'Stop', 'T']]) | |
255 | ||
256 | def decode(self, ss, es, data): | |
257 | # TODO: Either RX or TX could be omitted (optional probe). | |
258 | for (self.samplenum, pins) in data: | |
259 | ||
260 | # Note: Ignoring identical samples here for performance reasons | |
261 | # is not possible for this PD, at least not in the current state. | |
262 | # if self.oldpins == pins: | |
263 | # continue | |
264 | self.oldpins, (rx, tx) = pins, pins | |
265 | ||
266 | # State machine. | |
267 | for rxtx in (RX, TX): | |
268 | signal = rx if (rxtx == RX) else tx | |
269 | ||
270 | if self.state[rxtx] == 'WAIT FOR START BIT': | |
271 | self.wait_for_start_bit(rxtx, self.oldbit[rxtx], signal) | |
272 | elif self.state[rxtx] == 'GET START BIT': | |
273 | self.get_start_bit(rxtx, signal) | |
274 | elif self.state[rxtx] == 'GET DATA BITS': | |
275 | self.get_data_bits(rxtx, signal) | |
276 | elif self.state[rxtx] == 'GET PARITY BIT': | |
277 | self.get_parity_bit(rxtx, signal) | |
278 | elif self.state[rxtx] == 'GET STOP BITS': | |
279 | self.get_stop_bits(rxtx, signal) | |
280 | else: | |
281 | raise Exception('Invalid state: %s' % self.state[rxtx]) | |
282 | ||
283 | # Save current RX/TX values for the next round. | |
284 | self.oldbit[rxtx] = signal | |
285 |