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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2016 Vladimir Ermakov <vooon341@gmail.com>
##
## 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 3 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 sigrokdecode as srd
from functools import reduce
class SamplerateError(Exception):
pass
class Decoder(srd.Decoder):
api_version = 3
id = 'rgb_led_ws281x'
name = 'RGB LED (WS281x)'
longname = 'RGB LED string decoder (WS281x)'
desc = 'RGB LED string protocol (WS281x).'
license = 'gplv3+'
inputs = ['logic']
outputs = ['rgb_led_ws281x']
tags = ['Display', 'IC']
channels = (
{'id': 'din', 'name': 'DIN', 'desc': 'DIN data line'},
)
annotations = (
('bit', 'Bit'),
('reset', 'RESET'),
('rgb', 'RGB'),
)
annotation_rows = (
('bit', 'Bits', (0, 1)),
('rgb', 'RGB', (2,)),
)
def __init__(self):
self.reset()
def reset(self):
self.samplerate = None
self.oldpin = None
self.ss_packet = None
self.ss = None
self.es = None
self.bits = []
self.inreset = False
def start(self):
self.out_ann = self.register(srd.OUTPUT_ANN)
def metadata(self, key, value):
if key == srd.SRD_CONF_SAMPLERATE:
self.samplerate = value
def handle_bits(self, samplenum):
if len(self.bits) == 24:
grb = reduce(lambda a, b: (a << 1) | b, self.bits)
rgb = (grb & 0xff0000) >> 8 | (grb & 0x00ff00) << 8 | (grb & 0x0000ff)
self.put(self.ss_packet, samplenum, self.out_ann,
[2, ['#%06x' % rgb]])
self.bits = []
self.ss_packet = None
def decode(self):
if not self.samplerate:
raise SamplerateError('Cannot decode without samplerate.')
while True:
# TODO: Come up with more appropriate self.wait() conditions.
(pin,) = self.wait()
if self.oldpin is None:
self.oldpin = pin
continue
# Check RESET condition (manufacturer recommends 50 usec minimal,
# but real minimum is ~10 usec).
if not self.inreset and not pin and self.es is not None and \
(self.samplenum - self.es) / self.samplerate > 50e-6:
# Decode last bit value.
tH = (self.es - self.ss) / self.samplerate
bit_ = True if tH >= 625e-9 else False
self.bits.append(bit_)
self.handle_bits(self.es)
self.put(self.ss, self.es, self.out_ann, [0, ['%d' % bit_]])
self.put(self.es, self.samplenum, self.out_ann,
[1, ['RESET', 'RST', 'R']])
self.inreset = True
self.bits = []
self.ss_packet = None
self.ss = None
if not self.oldpin and pin:
# Rising edge.
if self.ss and self.es:
period = self.samplenum - self.ss
duty = self.es - self.ss
# Ideal duty for T0H: 33%, T1H: 66%.
bit_ = (duty / period) > 0.5
self.put(self.ss, self.samplenum, self.out_ann,
[0, ['%d' % bit_]])
self.bits.append(bit_)
self.handle_bits(self.samplenum)
if self.ss_packet is None:
self.ss_packet = self.samplenum
self.ss = self.samplenum
elif self.oldpin and not pin:
# Falling edge.
self.inreset = False
self.es = self.samplenum
self.oldpin = pin
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