2 ## This file is part of the libsigrokdecode project.
4 ## Copyright (C) 2013-2016 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
22 class SamplerateError(Exception):
25 class Decoder(srd.Decoder):
28 name = 'Guess bitrate'
29 longname = 'Guess bitrate/baudrate'
30 desc = 'Guess the bitrate/baudrate of a UART (or other) protocol.'
33 outputs = ['guess_bitrate']
35 {'id': 'data', 'name': 'Data', 'desc': 'Data line'},
38 ('bitrate', 'Bitrate / baudrate'),
42 self.put(self.ss_edge, self.samplenum, self.out_ann, data)
46 self.first_transition = True
50 self.out_ann = self.register(srd.OUTPUT_ANN)
52 self.initial_pins = [1] # TODO: Not generally correct.
54 def metadata(self, key, value):
55 if key == srd.SRD_CONF_SAMPLERATE:
56 self.samplerate = value
59 if not self.samplerate:
60 raise SamplerateError('Cannot decode without samplerate.')
63 # Wait for any transition/edge on the data line.
66 # Get the smallest distance between two transitions
67 # and use that to calculate the bitrate/baudrate.
68 if self.first_transition:
69 self.ss_edge = self.samplenum
70 self.first_transition = False
72 b = self.samplenum - self.ss_edge
73 if self.bitwidth is None or b < self.bitwidth:
75 bitrate = int(float(self.samplerate) / float(b))
76 self.putx([0, ['%d' % bitrate]])
77 self.ss_edge = self.samplenum