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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2019-2020 Philip Åkesson <philip.akesson@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 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/>.
##
from common.srdhelper import bitpack
import sigrokdecode as srd
class SamplerateError(Exception):
pass
class Pin:
SDQ, = range(1)
class Ann:
BIT, BYTE, BREAK, = range(3)
class Decoder(srd.Decoder):
api_version = 3
id = 'sdq'
name = 'SDQ'
longname = 'Texas Instruments SDQ'
desc = 'Texas Instruments SDQ. The SDQ protocol is also used by Apple.'
license = 'gplv2+'
inputs = ['logic']
outputs = []
tags = ['Embedded/industrial']
channels = (
{'id': 'sdq', 'name': 'SDQ', 'desc': 'Single wire SDQ data line.'},
)
options = (
{'id': 'bitrate', 'desc': 'Bit rate', 'default': 98425},
)
annotations = (
('bit', 'Bit'),
('byte', 'Byte'),
('break', 'Break'),
)
annotation_rows = (
('bits', 'Bits', (Ann.BIT,)),
('bytes', 'Bytes', (Ann.BYTE,)),
('breaks', 'Breaks', (Ann.BREAK,)),
)
def puts(self, data):
self.put(self.startsample, self.samplenum, self.out_ann, data)
def putetu(self, data):
self.put(self.startsample, self.startsample + int(self.bit_width), self.out_ann, data)
def putbetu(self, data):
self.put(self.bytepos, self.startsample + int(self.bit_width), self.out_ann, data)
def __init__(self):
self.reset()
def reset(self):
self.samplerate = None
self.startsample = 0
self.bits = []
self.bytepos = 0
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_bit(self, bit):
self.bits.append(bit)
self.putetu([Ann.BIT, [
'Bit: {:d}'.format(bit),
'{:d}'.format(bit),
]])
if len(self.bits) == 8:
byte = bitpack(self.bits)
self.putbetu([Ann.BYTE, [
'Byte: 0x{:02x}'.format(byte),
'0x{:02x}'.format(byte),
]])
self.bits = []
self.bytepos = 0
def handle_break(self):
self.puts([Ann.BREAK, ['Break', 'BR']])
self.bits = []
self.startsample = self.samplenum
self.bytepos = 0
def decode(self):
if not self.samplerate:
raise SamplerateError('Cannot decode without samplerate.')
self.bit_width = float(self.samplerate) / float(self.options['bitrate'])
self.half_bit_width = self.bit_width / 2.0
# BREAK if the line is low for longer than this.
break_threshold = self.bit_width * 1.2
# Wait until the line is high before inspecting input data.
sdq, = self.wait({Pin.SDQ: 'h'})
while True:
# Get the length of a low pulse (falling to rising edge).
sdq, = self.wait({Pin.SDQ: 'f'})
self.startsample = self.samplenum
if self.bytepos == 0:
self.bytepos = self.samplenum
sdq, = self.wait({Pin.SDQ: 'r'})
# Check for 0 or 1 data bits, or the BREAK symbol.
delta = self.samplenum - self.startsample
if delta > break_threshold:
self.handle_break()
elif delta > self.half_bit_width:
self.handle_bit(0)
else:
self.handle_bit(1)
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