From: Christoph Rackwitz Date: Mon, 18 Sep 2017 19:15:09 +0000 (+0200) Subject: Add a gray code and rotary encoder protocol decoder. X-Git-Url: http://sigrok.org/gitweb/?a=commitdiff_plain;h=b9b63977498f2114cf41d9039223481cbcaf3a45;p=libsigrokdecode.git Add a gray code and rotary encoder protocol decoder. --- diff --git a/decoders/graycode/__init__.py b/decoders/graycode/__init__.py new file mode 100644 index 0000000..90ef824 --- /dev/null +++ b/decoders/graycode/__init__.py @@ -0,0 +1,24 @@ +## +## This file is part of the libsigrokdecode project. +## +## Copyright (C) 2017 Christoph Rackwitz +## +## 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, see . +## + +''' +Gray code and rotary encoder protocol. +''' + +from .pd import Decoder diff --git a/decoders/graycode/pd.py b/decoders/graycode/pd.py new file mode 100644 index 0000000..2edc837 --- /dev/null +++ b/decoders/graycode/pd.py @@ -0,0 +1,206 @@ +## +## This file is part of the libsigrokdecode project. +## +## Copyright (C) 2017 Christoph Rackwitz +## +## 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, see . +## + +import math +import sigrokdecode as srd +from collections import deque + +def bitpack(bits): + res = 0 + for i, b in enumerate(bits): + res |= b << i + return res + +def bitunpack(num, minbits=0): + res = [] + while num or minbits > 0: + res.append(num & 1) + num >>= 1 + minbits -= 1 + return tuple(res) + +def gray_encode(plain): + return plain & (plain >> 1) + +def gray_decode(gray): + temp = gray + temp ^= (temp >> 8) + temp ^= (temp >> 4) + temp ^= (temp >> 2) + temp ^= (temp >> 1) + return temp + +def prefix_fmt(value, emin=None): + sgn = (value > 0) - (value < 0) + value = abs(value) + p = math.log10(value) if value else 0 + value = sgn * math.floor(value * 10**int(3 - p)) * 10**-int(3 - p) + e = p // 3 * 3 + if emin is not None and e < emin: + e = emin + value *= 10**-e + p -= e + decimals = 2 - int(p) + prefixes = {-9: 'n', -6: 'µ', -3: 'm', 0: '', 3: 'k', 6: 'M', 9: 'G'} + return '{0:.{1}f} {2}'.format(value, decimals, prefixes[e]) + +class ChannelMapError(Exception): + pass + +class Value: + def __init__(self, onchange): + self.onchange = onchange + self.timestamp = None + self.value = None + + def get(self): + return self.value + + def set(self, timestamp, newval): + if newval != self.value: + if self.value is not None: + self.onchange(self.timestamp, self.value, timestamp, newval) + + self.value = newval + self.timestamp = timestamp + elif False: + if self.value is not None: + self.onchange(self.timestamp, self.value, timestamp, newval) + +MAX_CHANNELS = 8 # 10 channels causes some weird problems... + +class Decoder(srd.Decoder): + api_version = 3 + id = 'graycode' + name = 'Gray code' + longname = 'Gray code and rotary encoder' + desc = 'Accumulate rotary encoder increments, provide timing statistics.' + license = 'gplv2+' + inputs = ['logic'] + outputs = ['graycode'] + optional_channels = tuple( + {'id': 'd{}'.format(i), 'name': 'D{}'.format(i), 'desc': 'Data line {}'.format(i)} + for i in range(MAX_CHANNELS) + ) + options = ( + {'id': 'edges', 'desc': 'Edges per rotation', 'default': 0}, + {'id': 'avg_period', 'desc': 'Averaging period', 'default': 10}, + ) + annotations = ( + ('phase', 'Phase'), + ('increment', 'Increment'), + ('count', 'Count'), + ('turns', 'Turns'), + ('interval', 'Interval'), + ('average', 'Average'), + ('rpm', 'Rate'), + ) + annotation_rows = tuple((u, v, (i,)) for i, (u, v) in enumerate(annotations)) + + def __init__(self): + self.num_channels = 0 + self.samplerate = None + self.last_n = deque() + + self.phase = Value(self.on_phase) + self.increment = Value(self.on_increment) + self.count = Value(self.on_count) + self.turns = Value(self.on_turns) + + def on_phase(self, told, vold, tnew, vnew): + self.put(told, tnew, self.out_ann, [0, ['{}'.format(vold)]]) + + def on_increment(self, told, vold, tnew, vnew): + if vold == 0: + message = '0' + elif abs(vold) == self.ENCODER_STEPS // 2: + message = '±π' + else: + message = '{:+d}'.format(vold) + self.put(told, tnew, self.out_ann, [1, [message]]) + + def on_count(self, told, vold, tnew, vnew): + self.put(told, tnew, self.out_ann, [2, ['{}'.format(vold)]]) + + def on_turns(self, told, vold, tnew, vnew): + self.put(told, tnew, self.out_ann, [3, ['{:+d}'.format(vold)]]) + + def metadata(self, key, value): + if key == srd.SRD_CONF_SAMPLERATE: + self.samplerate = value + + def start(self): + self.out_ann = self.register(srd.OUTPUT_ANN) + + def decode(self): + chmask = [self.has_channel(i) for i in range(MAX_CHANNELS)] + self.num_channels = sum(chmask) + if chmask != [i < self.num_channels for i in range(MAX_CHANNELS)]: + raise ChannelMapError('Assigned channels need to be contiguous') + + self.ENCODER_STEPS = 1 << self.num_channels + + startbits = self.wait() + curtime = self.samplenum + + self.turns.set(self.samplenum, 0) + self.count.set(self.samplenum, 0) + self.phase.set(self.samplenum, gray_decode(bitpack(startbits[:self.num_channels]))) + + while True: + prevtime = curtime + bits = self.wait([{i: 'e'} for i in range(self.num_channels)]) + curtime = self.samplenum + + oldcount = self.count.get() + oldphase = self.phase.get() + + newphase = gray_decode(bitpack(bits[:self.num_channels])) + self.phase.set(self.samplenum, newphase) + + phasedelta_raw = (newphase - oldphase + (self.ENCODER_STEPS // 2 - 1)) % self.ENCODER_STEPS - (self.ENCODER_STEPS // 2 - 1) + phasedelta = phasedelta_raw + self.increment.set(self.samplenum, phasedelta) + if abs(phasedelta) == self.ENCODER_STEPS // 2: + phasedelta = 0 + + self.count.set(self.samplenum, self.count.get() + phasedelta) + + if self.options['edges']: + self.turns.set(self.samplenum, self.count.get() // self.options['edges']) + + if self.samplerate is not None: + period = (curtime - prevtime) / self.samplerate + freq = abs(phasedelta_raw) / period + + self.put(prevtime, curtime, self.out_ann, [4, [ + '{}s, {}Hz'.format(prefix_fmt(period), prefix_fmt(freq))]]) + + if self.options['avg_period']: + self.last_n.append((abs(phasedelta_raw), period)) + if len(self.last_n) > self.options['avg_period']: + self.last_n.popleft() + + avg_period = sum(v for u, v in self.last_n) / (sum(u for u, v in self.last_n) or 1) + self.put(prevtime, curtime, self.out_ann, [5, [ + '{}s, {}Hz'.format(prefix_fmt(avg_period), + prefix_fmt(1 / avg_period))]]) + + if self.options['edges']: + self.put(prevtime, curtime, self.out_ann, [6, ['{}rpm'.format(prefix_fmt(60 * freq / self.options['edges'], emin=0))]])