2 ## This file is part of the libsigrokdecode project.
4 ## Copyright (C) 2011-2014 Uwe Hermann <uwe@hermann-uwe.de>
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.
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.
16 ## You should have received a copy of the GNU General Public License
17 ## along with this program; if not, see <http://www.gnu.org/licenses/>.
20 import sigrokdecode as srd
21 from math import floor, ceil
27 [<ptype>, <rxtx>, <pdata>]
29 This is the list of <ptype>s and their respective <pdata> values:
30 - 'STARTBIT': The data is the (integer) value of the start bit (0/1).
31 - 'DATA': This is always a tuple containing two items:
32 - 1st item: the (integer) value of the UART data. Valid values
33 range from 0 to 511 (as the data can be up to 9 bits in size).
34 - 2nd item: the list of individual data bits and their ss/es numbers.
35 - 'PARITYBIT': The data is the (integer) value of the parity bit (0/1).
36 - 'STOPBIT': The data is the (integer) value of the stop bit (0 or 1).
37 - 'INVALID STARTBIT': The data is the (integer) value of the start bit (0/1).
38 - 'INVALID STOPBIT': The data is the (integer) value of the stop bit (0/1).
39 - 'PARITY ERROR': The data is a tuple with two entries. The first one is
40 the expected parity value, the second is the actual parity value.
43 The <rxtx> field is 0 for RX packets, 1 for TX packets.
46 # Used for differentiating between the two data directions.
50 # Given a parity type to check (odd, even, zero, one), the value of the
51 # parity bit, the value of the data, and the length of the data (5-9 bits,
52 # usually 8 bits) return True if the parity is correct, False otherwise.
53 # 'none' is _not_ allowed as value for 'parity_type'.
54 def parity_ok(parity_type, parity_bit, data, num_data_bits):
56 # Handle easy cases first (parity bit is always 1 or 0).
57 if parity_type == 'zero':
58 return parity_bit == 0
59 elif parity_type == 'one':
60 return parity_bit == 1
62 # Count number of 1 (high) bits in the data (and the parity bit itself!).
63 ones = bin(data).count('1') + parity_bit
65 # Check for odd/even parity.
66 if parity_type == 'odd':
67 return (ones % 2) == 1
68 elif parity_type == 'even':
69 return (ones % 2) == 0
71 class SamplerateError(Exception):
74 class ChannelError(Exception):
77 class Decoder(srd.Decoder):
81 longname = 'Universal Asynchronous Receiver/Transmitter'
82 desc = 'Asynchronous, serial bus.'
87 # Allow specifying only one of the signals, e.g. if only one data
88 # direction exists (or is relevant).
89 {'id': 'rx', 'name': 'RX', 'desc': 'UART receive line'},
90 {'id': 'tx', 'name': 'TX', 'desc': 'UART transmit line'},
93 {'id': 'baudrate', 'desc': 'Baud rate', 'default': 115200},
94 {'id': 'num_data_bits', 'desc': 'Data bits', 'default': 8,
95 'values': (5, 6, 7, 8, 9)},
96 {'id': 'parity_type', 'desc': 'Parity type', 'default': 'none',
97 'values': ('none', 'odd', 'even', 'zero', 'one')},
98 {'id': 'parity_check', 'desc': 'Check parity?', 'default': 'yes',
99 'values': ('yes', 'no')},
100 {'id': 'num_stop_bits', 'desc': 'Stop bits', 'default': 1.0,
101 'values': (0.0, 0.5, 1.0, 1.5)},
102 {'id': 'bit_order', 'desc': 'Bit order', 'default': 'lsb-first',
103 'values': ('lsb-first', 'msb-first')},
104 {'id': 'format', 'desc': 'Data format', 'default': 'hex',
105 'values': ('ascii', 'dec', 'hex', 'oct', 'bin')},
106 {'id': 'invert_rx', 'desc': 'Invert RX?', 'default': 'no',
107 'values': ('yes', 'no')},
108 {'id': 'invert_tx', 'desc': 'Invert TX?', 'default': 'no',
109 'values': ('yes', 'no')},
112 ('rx-data', 'RX data'),
113 ('tx-data', 'TX data'),
114 ('rx-start', 'RX start bits'),
115 ('tx-start', 'TX start bits'),
116 ('rx-parity-ok', 'RX parity OK bits'),
117 ('tx-parity-ok', 'TX parity OK bits'),
118 ('rx-parity-err', 'RX parity error bits'),
119 ('tx-parity-err', 'TX parity error bits'),
120 ('rx-stop', 'RX stop bits'),
121 ('tx-stop', 'TX stop bits'),
122 ('rx-warnings', 'RX warnings'),
123 ('tx-warnings', 'TX warnings'),
124 ('rx-data-bits', 'RX data bits'),
125 ('tx-data-bits', 'TX data bits'),
128 ('rx-data', 'RX', (0, 2, 4, 6, 8)),
129 ('rx-data-bits', 'RX bits', (12,)),
130 ('rx-warnings', 'RX warnings', (10,)),
131 ('tx-data', 'TX', (1, 3, 5, 7, 9)),
132 ('tx-data-bits', 'TX bits', (13,)),
133 ('tx-warnings', 'TX warnings', (11,)),
138 ('rxtx', 'RX/TX dump'),
140 idle_state = ['WAIT FOR START BIT', 'WAIT FOR START BIT']
142 def putx(self, rxtx, data):
143 s, halfbit = self.startsample[rxtx], self.bit_width / 2.0
144 self.put(s - floor(halfbit), self.samplenum + ceil(halfbit), self.out_ann, data)
146 def putpx(self, rxtx, data):
147 s, halfbit = self.startsample[rxtx], self.bit_width / 2.0
148 self.put(s - floor(halfbit), self.samplenum + ceil(halfbit), self.out_python, data)
150 def putg(self, data):
151 s, halfbit = self.samplenum, self.bit_width / 2.0
152 self.put(s - floor(halfbit), s + ceil(halfbit), self.out_ann, data)
154 def putp(self, data):
155 s, halfbit = self.samplenum, self.bit_width / 2.0
156 self.put(s - floor(halfbit), s + ceil(halfbit), self.out_python, data)
158 def putbin(self, rxtx, data):
159 s, halfbit = self.startsample[rxtx], self.bit_width / 2.0
160 self.put(s - floor(halfbit), self.samplenum + ceil(halfbit), self.out_binary, data)
163 self.samplerate = None
165 self.frame_start = [-1, -1]
166 self.startbit = [-1, -1]
167 self.cur_data_bit = [0, 0]
168 self.datavalue = [0, 0]
169 self.paritybit = [-1, -1]
170 self.stopbit1 = [-1, -1]
171 self.startsample = [-1, -1]
172 self.state = ['WAIT FOR START BIT', 'WAIT FOR START BIT']
174 self.oldpins = [-1, -1]
175 self.databits = [[], []]
178 self.out_python = self.register(srd.OUTPUT_PYTHON)
179 self.out_binary = self.register(srd.OUTPUT_BINARY)
180 self.out_ann = self.register(srd.OUTPUT_ANN)
181 self.bw = (self.options['num_data_bits'] + 7) // 8
183 def metadata(self, key, value):
184 if key == srd.SRD_CONF_SAMPLERATE:
185 self.samplerate = value
186 # The width of one UART bit in number of samples.
187 self.bit_width = float(self.samplerate) / float(self.options['baudrate'])
189 # Return true if we reached the middle of the desired bit, false otherwise.
190 def reached_bit(self, rxtx, bitnum):
191 # bitpos is the samplenumber which is in the middle of the
192 # specified UART bit (0 = start bit, 1..x = data, x+1 = parity bit
193 # (if used) or the first stop bit, and so on).
194 # The samples within bit are 0, 1, ..., (bit_width - 1), therefore
195 # index of the middle sample within bit window is (bit_width - 1) / 2.
196 bitpos = self.frame_start[rxtx] + (self.bit_width - 1) / 2.0
197 bitpos += bitnum * self.bit_width
198 if self.samplenum >= bitpos:
202 def reached_bit_last(self, rxtx, bitnum):
203 bitpos = self.frame_start[rxtx] + ((bitnum + 1) * self.bit_width)
204 if self.samplenum >= bitpos:
208 def wait_for_start_bit(self, rxtx, old_signal, signal):
209 # The start bit is always 0 (low). As the idle UART (and the stop bit)
210 # level is 1 (high), the beginning of a start bit is a falling edge.
211 if not (old_signal == 1 and signal == 0):
214 # Save the sample number where the start bit begins.
215 self.frame_start[rxtx] = self.samplenum
217 self.state[rxtx] = 'GET START BIT'
219 def get_start_bit(self, rxtx, signal):
220 # Skip samples until we're in the middle of the start bit.
221 if not self.reached_bit(rxtx, 0):
224 self.startbit[rxtx] = signal
226 # The startbit must be 0. If not, we report an error and wait
227 # for the next start bit (assuming this one was spurious).
228 if self.startbit[rxtx] != 0:
229 self.putp(['INVALID STARTBIT', rxtx, self.startbit[rxtx]])
230 self.putg([rxtx + 10, ['Frame error', 'Frame err', 'FE']])
231 self.state[rxtx] = 'WAIT FOR START BIT'
234 self.cur_data_bit[rxtx] = 0
235 self.datavalue[rxtx] = 0
236 self.startsample[rxtx] = -1
238 self.state[rxtx] = 'GET DATA BITS'
240 self.putp(['STARTBIT', rxtx, self.startbit[rxtx]])
241 self.putg([rxtx + 2, ['Start bit', 'Start', 'S']])
243 def get_data_bits(self, rxtx, signal):
244 # Skip samples until we're in the middle of the desired data bit.
245 if not self.reached_bit(rxtx, self.cur_data_bit[rxtx] + 1):
248 # Save the sample number of the middle of the first data bit.
249 if self.startsample[rxtx] == -1:
250 self.startsample[rxtx] = self.samplenum
252 # Get the next data bit in LSB-first or MSB-first fashion.
253 if self.options['bit_order'] == 'lsb-first':
254 self.datavalue[rxtx] >>= 1
255 self.datavalue[rxtx] |= \
256 (signal << (self.options['num_data_bits'] - 1))
258 self.datavalue[rxtx] <<= 1
259 self.datavalue[rxtx] |= (signal << 0)
261 self.putg([rxtx + 12, ['%d' % signal]])
263 # Store individual data bits and their start/end samplenumbers.
264 s, halfbit = self.samplenum, int(self.bit_width / 2)
265 self.databits[rxtx].append([signal, s - halfbit, s + halfbit])
267 # Return here, unless we already received all data bits.
268 if self.cur_data_bit[rxtx] < self.options['num_data_bits'] - 1:
269 self.cur_data_bit[rxtx] += 1
272 self.state[rxtx] = 'GET PARITY BIT'
274 self.putpx(rxtx, ['DATA', rxtx,
275 (self.datavalue[rxtx], self.databits[rxtx])])
277 b = self.datavalue[rxtx]
278 formatted = self.format_value(b)
279 if formatted is not None:
280 self.putx(rxtx, [rxtx, [formatted]])
282 bdata = b.to_bytes(self.bw, byteorder='big')
283 self.putbin(rxtx, [rxtx, bdata])
284 self.putbin(rxtx, [2, bdata])
286 self.databits[rxtx] = []
288 def format_value(self, v):
289 # Format value 'v' according to configured options.
290 # Reflects the user selected kind of representation, as well as
291 # the number of data bits in the UART frames.
293 fmt, bits = self.options['format'], self.options['num_data_bits']
295 # Assume "is printable" for values from 32 to including 126,
296 # below 32 is "control" and thus not printable, above 127 is
297 # "not ASCII" in its strict sense, 127 (DEL) is not printable,
298 # fall back to hex representation for non-printables.
300 if v in range(32, 126 + 1):
302 hexfmt = "[{:02X}]" if bits <= 8 else "[{:03X}]"
303 return hexfmt.format(v)
305 # Mere number to text conversion without prefix and padding
306 # for the "decimal" output format.
308 return "{:d}".format(v)
310 # Padding with leading zeroes for hex/oct/bin formats, but
311 # without a prefix for density -- since the format is user
312 # specified, there is no ambiguity.
314 digits = (bits + 4 - 1) // 4
317 digits = (bits + 3 - 1) // 3
324 if fmtchar is not None:
325 fmt = "{{:0{:d}{:s}}}".format(digits, fmtchar)
330 def get_parity_bit(self, rxtx, signal):
331 # If no parity is used/configured, skip to the next state immediately.
332 if self.options['parity_type'] == 'none':
333 self.state[rxtx] = 'GET STOP BITS'
336 # Skip samples until we're in the middle of the parity bit.
337 if not self.reached_bit(rxtx, self.options['num_data_bits'] + 1):
340 self.paritybit[rxtx] = signal
342 self.state[rxtx] = 'GET STOP BITS'
344 if parity_ok(self.options['parity_type'], self.paritybit[rxtx],
345 self.datavalue[rxtx], self.options['num_data_bits']):
346 self.putp(['PARITYBIT', rxtx, self.paritybit[rxtx]])
347 self.putg([rxtx + 4, ['Parity bit', 'Parity', 'P']])
349 # TODO: Return expected/actual parity values.
350 self.putp(['PARITY ERROR', rxtx, (0, 1)]) # FIXME: Dummy tuple...
351 self.putg([rxtx + 6, ['Parity error', 'Parity err', 'PE']])
353 # TODO: Currently only supports 1 stop bit.
354 def get_stop_bits(self, rxtx, signal):
355 # Skip samples until we're in the middle of the stop bit(s).
356 skip_parity = 0 if self.options['parity_type'] == 'none' else 1
357 b = self.options['num_data_bits'] + 1 + skip_parity
358 if not self.reached_bit(rxtx, b):
361 self.stopbit1[rxtx] = signal
363 # Stop bits must be 1. If not, we report an error.
364 if self.stopbit1[rxtx] != 1:
365 self.putp(['INVALID STOPBIT', rxtx, self.stopbit1[rxtx]])
366 self.putg([rxtx + 10, ['Frame error', 'Frame err', 'FE']])
367 # TODO: Abort? Ignore the frame? Other?
369 self.state[rxtx] = 'WAIT FOR START BIT'
371 self.putp(['STOPBIT', rxtx, self.stopbit1[rxtx]])
372 self.putg([rxtx + 4, ['Stop bit', 'Stop', 'T']])
374 def decode(self, ss, es, data):
375 if not self.samplerate:
376 raise SamplerateError('Cannot decode without samplerate.')
377 for (self.samplenum, pins) in data:
379 # We want to skip identical samples for performance reasons but,
380 # for now, we can only do that when we are in the idle state
381 # (meaning both channels are waiting for the start bit).
382 if self.state == self.idle_state and self.oldpins == pins:
385 self.oldpins, (rx, tx) = pins, pins
387 if self.options['invert_rx'] == 'yes':
389 if self.options['invert_tx'] == 'yes':
392 # Either RX or TX (but not both) can be omitted.
393 has_pin = [rx in (0, 1), tx in (0, 1)]
394 if has_pin == [False, False]:
395 raise ChannelError('Either TX or RX (or both) pins required.')
398 for rxtx in (RX, TX):
399 # Don't try to handle RX (or TX) if not supplied.
400 if not has_pin[rxtx]:
403 signal = rx if (rxtx == RX) else tx
405 if self.state[rxtx] == 'WAIT FOR START BIT':
406 self.wait_for_start_bit(rxtx, self.oldbit[rxtx], signal)
407 elif self.state[rxtx] == 'GET START BIT':
408 self.get_start_bit(rxtx, signal)
409 elif self.state[rxtx] == 'GET DATA BITS':
410 self.get_data_bits(rxtx, signal)
411 elif self.state[rxtx] == 'GET PARITY BIT':
412 self.get_parity_bit(rxtx, signal)
413 elif self.state[rxtx] == 'GET STOP BITS':
414 self.get_stop_bits(rxtx, signal)
416 # Save current RX/TX values for the next round.
417 self.oldbit[rxtx] = signal