2 ## This file is part of the libsigrokdecode project.
4 ## Copyright (C) 2013 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, write to the Free Software
18 ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
21 import sigrokdecode as srd
23 class SamplerateError(Exception):
26 class Decoder(srd.Decoder):
29 name = 'Guess bitrate'
30 longname = 'Guess bitrate/baudrate'
31 desc = 'Guess the bitrate/baudrate of a UART (or other) protocol.'
34 outputs = ['guess_bitrate']
36 {'id': 'data', 'name': 'Data', 'desc': 'Data line'},
39 ('bitrate', 'Bitrate / baudrate'),
43 self.put(self.ss_edge, self.samplenum, self.out_ann, data)
48 self.first_transition = True
52 self.out_ann = self.register(srd.OUTPUT_ANN)
54 def metadata(self, key, value):
55 if key == srd.SRD_CONF_SAMPLERATE:
56 self.samplerate = value
58 def decode(self, ss, es, data):
59 if not self.samplerate:
60 raise SamplerateError('Cannot decode without samplerate.')
61 for (self.samplenum, pins) in data:
65 # Wait for any transition on the data line.
66 if data == self.olddata:
69 # Initialize first self.olddata with the first sample value.
70 if self.olddata is None:
74 # Get the smallest distance between two transitions
75 # and use that to calculate the bitrate/baudrate.
76 if self.first_transition:
77 self.ss_edge = self.samplenum
78 self.first_transition = False
80 b = self.samplenum - self.ss_edge
81 if self.bitwidth is None or b < self.bitwidth:
83 bitrate = int(float(self.samplerate) / float(b))
84 self.putx([0, ['%d' % bitrate]])
85 self.ss_edge = self.samplenum