diff options
Diffstat (limited to 'decoders/guess_bitrate')
| -rw-r--r-- | decoders/guess_bitrate/Makefile.am | 26 | ||||
| -rw-r--r-- | decoders/guess_bitrate/__init__.py | 38 | ||||
| -rw-r--r-- | decoders/guess_bitrate/pd.py | 88 |
3 files changed, 152 insertions, 0 deletions
diff --git a/decoders/guess_bitrate/Makefile.am b/decoders/guess_bitrate/Makefile.am new file mode 100644 index 0000000..7c162f6 --- /dev/null +++ b/decoders/guess_bitrate/Makefile.am @@ -0,0 +1,26 @@ +## +## This file is part of the libsigrokdecode project. +## +## Copyright (C) 2013 Uwe Hermann <uwe@hermann-uwe.de> +## +## This program is free software; you can redistribute it and/or modify +## it under the terms of the GNU General Public License as published by +## the Free Software Foundation; either version 2 of the License, or +## (at your option) any later version. +## +## This program is distributed in the hope that it will be useful, +## but WITHOUT ANY WARRANTY; without even the implied warranty of +## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +## GNU General Public License for more details. +## +## You should have received a copy of the GNU General Public License +## along with this program; if not, write to the Free Software +## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA +## + +pkgdatadir = $(DECODERS_DIR)/guess_bitrate + +dist_pkgdata_DATA = __init__.py pd.py + +CLEANFILES = *.pyc + diff --git a/decoders/guess_bitrate/__init__.py b/decoders/guess_bitrate/__init__.py new file mode 100644 index 0000000..86f9466 --- /dev/null +++ b/decoders/guess_bitrate/__init__.py @@ -0,0 +1,38 @@ +## +## This file is part of the libsigrokdecode project. +## +## Copyright (C) 2013 Uwe Hermann <uwe@hermann-uwe.de> +## +## This program is free software; you can redistribute it and/or modify +## it under the terms of the GNU General Public License as published by +## the Free Software Foundation; either version 2 of the License, or +## (at your option) any later version. +## +## This program is distributed in the hope that it will be useful, +## but WITHOUT ANY WARRANTY; without even the implied warranty of +## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +## GNU General Public License for more details. +## +## You should have received a copy of the GNU General Public License +## along with this program; if not, write to the Free Software +## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA +## + +''' +This protocol decoder tries to guess the bitrate / baudrate of the +communication on the specified probe. Typically this will be used to +guess / detect the baudrate used in a UART communication snippet, but it +could also be used to guess bitrates of certain other protocols or buses. + +It should be noted that this is nothing more than a simple guess / heuristic, +and that there are various cases in practice where the detection of the +bitrate or baudrate will not necessarily have the expected result. + +The precision of the estimated bitrate / baudrate will also depend on the +samplerate used to sample the respective probe. For good results it is +recommended to use a logic analyzer samplerate that is much higher than +the expected bitrate/baudrate that might be used on the probe. +''' + +from .pd import * + diff --git a/decoders/guess_bitrate/pd.py b/decoders/guess_bitrate/pd.py new file mode 100644 index 0000000..585bd76 --- /dev/null +++ b/decoders/guess_bitrate/pd.py @@ -0,0 +1,88 @@ +## +## This file is part of the libsigrokdecode project. +## +## Copyright (C) 2013 Uwe Hermann <uwe@hermann-uwe.de> +## +## This program is free software; you can redistribute it and/or modify +## it under the terms of the GNU General Public License as published by +## the Free Software Foundation; either version 2 of the License, or +## (at your option) any later version. +## +## This program is distributed in the hope that it will be useful, +## but WITHOUT ANY WARRANTY; without even the implied warranty of +## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +## GNU General Public License for more details. +## +## You should have received a copy of the GNU General Public License +## along with this program; if not, write to the Free Software +## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA +## + +# Bitrate / baudrate guessing protocol decoder + +import sigrokdecode as srd + +class Decoder(srd.Decoder): + api_version = 1 + id = 'guess_bitrate' + name = 'Guess bitrate' + longname = 'Guess bitrate/baudrate' + desc = 'Guess the bitrate/baudrate of a UART (or other) protocol.' + license = 'gplv2+' + inputs = ['logic'] + outputs = ['guess_bitrate'] + probes = [ + {'id': 'data', 'name': 'Data', 'desc': 'Data line'}, + ] + optional_probes = [] + options = {} + annotations = [ + ['bitrate', 'Bitrate / baudrate'], + ] + + def putx(self, data): + self.put(self.ss_edge, self.samplenum, self.out_ann, data) + + def __init__(self, **kwargs): + self.olddata = None + self.ss_edge = None + self.first_transition = True + self.bitwidth = None + + def start(self, metadata): + self.samplerate = metadata['samplerate'] + # self.out_proto = self.add(srd.OUTPUT_PROTO, 'guess_bitrate') + self.out_ann = self.add(srd.OUTPUT_ANN, 'guess_bitrate') + + def report(self): + pass + + def decode(self, ss, es, data): + for (self.samplenum, pins) in data: + + data = pins[0] + + # Wait for any transition on the data line. + if data == self.olddata: + continue + + # Initialize first self.olddata with the first sample value. + if self.olddata == None: + self.olddata = data + continue + + # Get the smallest distance between two transitions + # and use that to calculate the bitrate/baudrate. + if self.first_transition == True: + self.ss_edge = self.samplenum + self.first_transition = False + else: + b = self.samplenum - self.ss_edge + if self.bitwidth == None or b < self.bitwidth: + self.bitwidth = b + bitrate = int(float(self.samplerate) / float(b)) + self.putx([0, ['%d' % bitrate]]) + self.ss_edge = self.samplenum + + self.olddata = data + |