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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2017 Christoph Rackwitz <christoph.rackwitz@rwth-aachen.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, see <http://www.gnu.org/licenses/>.
##
import math
import sigrokdecode as srd
from collections import deque
from common.srdhelper import bitpack, bitunpack
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.reset()
def reset(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:
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))]])
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