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##
## This file is part of the sigrok project.
##
## Copyright (C) 2012 Iztok Jeras <iztok.jeras@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, write to the Free Software
## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
##
# 1-Wire protocol decoder (link layer)
import sigrokdecode as srd
class Decoder(srd.Decoder):
api_version = 1
id = 'onewire_link'
name = '1-Wire link layer'
longname = '1-Wire serial communication bus (link layer)'
desc = 'Bidirectional, half-duplex, asynchronous serial bus.'
license = 'gplv2+'
inputs = ['logic']
outputs = ['onewire_link']
probes = [
{'id': 'owr', 'name': 'OWR', 'desc': '1-Wire bus'},
]
optional_probes = [
{'id': 'pwr', 'name': 'PWR', 'desc': '1-Wire power'},
]
options = {
'overdrive': ['Overdrive', 1],
# Time options (specified in number of samplerate periods):
'cnt_normal_bit': ['Normal mode sample bit time', 0],
'cnt_normal_slot': ['Normal mode data slot time', 0],
'cnt_normal_presence': ['Normal mode sample presence time', 0],
'cnt_normal_reset': ['Normal mode reset time', 0],
'cnt_overdrive_bit': ['Overdrive mode sample bit time', 0],
'cnt_overdrive_slot': ['Overdrive mode data slot time', 0],
'cnt_overdrive_presence': ['Overdrive mode sample presence time', 0],
'cnt_overdrive_reset': ['Overdrive mode reset time', 0],
}
annotations = [
['Link', 'Link layer events (reset, presence, bit slots)'],
]
def __init__(self, **kwargs):
self.samplenum = 0
# Link layer variables
self.state = 'WAIT FOR FALLING EDGE'
self.present = 0
self.bit = 0
self.bit_cnt = 0
self.command = 0
self.overdrive = 0
# Event timing variables
self.fall = 0
self.rise = 0
def start(self, metadata):
self.out_proto = self.add(srd.OUTPUT_PROTO, 'onewire_link')
self.out_ann = self.add(srd.OUTPUT_ANN, 'onewire_link')
self.samplerate = metadata['samplerate']
# Check if samplerate is appropriate.
if self.options['overdrive']:
self.put(0, 0, self.out_ann, [0,
['NOTE: Sample rate checks assume overdrive mode.']])
if self.samplerate < 2000000:
self.put(0, 0, self.out_ann, [0,
['ERROR: Sampling rate is too low. Must be above 2MHz ' +
'for proper overdrive mode decoding.']])
elif self.samplerate < 5000000:
self.put(0, 0, self.out_ann, [0,
['WARNING: Sampling rate is suggested to be above 5MHz ' +
'for proper overdrive mode decoding.']])
else:
self.put(0, 0, self.out_ann, [0,
['NOTE: Sample rate checks assume normal mode only.']])
if self.samplerate < 400000:
self.put(0, 0, self.out_ann, [0,
['ERROR: Sampling rate is too low. Must be above ' +
'400kHz for proper normal mode decoding.']])
elif (self.samplerate < 1000000):
self.put(0, 0, self.out_ann, [0,
['WARNING: Sampling rate is suggested to be above ' +
'1MHz for proper normal mode decoding.']])
# The default 1-Wire time base is 30us. This is used to calculate
# sampling times.
samplerate = float(self.samplerate)
if self.options['cnt_normal_bit']:
self.cnt_normal_bit = self.options['cnt_normal_bit']
else:
self.cnt_normal_bit = int(samplerate * 0.000015) - 1 # 15ns
if self.options['cnt_normal_slot']:
self.cnt_normal_slot = self.options['cnt_normal_slot']
else:
self.cnt_normal_slot = int(samplerate * 0.000060) - 1 # 60ns
if self.options['cnt_normal_presence']:
self.cnt_normal_presence = self.options['cnt_normal_presence']
else:
self.cnt_normal_presence = int(samplerate * 0.000075) - 1 # 75ns
if self.options['cnt_normal_reset']:
self.cnt_normal_reset = self.options['cnt_normal_reset']
else:
self.cnt_normal_reset = int(samplerate * 0.000480) - 1 # 480ns
if self.options['cnt_overdrive_bit']:
self.cnt_overdrive_bit = self.options['cnt_overdrive_bit']
else:
self.cnt_overdrive_bit = int(samplerate * 0.000002) - 1 # 2ns
if self.options['cnt_overdrive_slot']:
self.cnt_overdrive_slot = self.options['cnt_overdrive_slot']
else:
self.cnt_overdrive_slot = int(samplerate * 0.0000073) - 1 # 6ns+1.3ns
if self.options['cnt_overdrive_presence']:
self.cnt_overdrive_presence = self.options['cnt_overdrive_presence']
else:
self.cnt_overdrive_presence = int(samplerate * 0.000010) - 1 # 10ns
if self.options['cnt_overdrive_reset']:
self.cnt_overdrive_reset = self.options['cnt_overdrive_reset']
else:
self.cnt_overdrive_reset = int(samplerate * 0.000048) - 1 # 48ns
# Organize values into lists.
self.cnt_bit = [self.cnt_normal_bit, self.cnt_overdrive_bit]
self.cnt_presence = [self.cnt_normal_presence, self.cnt_overdrive_presence]
self.cnt_reset = [self.cnt_normal_reset, self.cnt_overdrive_reset]
self.cnt_slot = [self.cnt_normal_slot, self.cnt_overdrive_slot]
# Check if sample times are in the allowed range.
time_min = float(self.cnt_normal_bit) / self.samplerate
time_max = float(self.cnt_normal_bit + 1) / self.samplerate
if (time_min < 0.000005) or (time_max > 0.000015):
self.put(0, 0, self.out_ann, [0,
['WARNING: The normal mode data sample time interval ' +
'(%2.1fus-%2.1fus) should be inside (5.0us, 15.0us).'
% (time_min * 1000000, time_max * 1000000)]])
time_min = float(self.cnt_normal_presence) / self.samplerate
time_max = float(self.cnt_normal_presence + 1) / self.samplerate
if (time_min < 0.0000681) or (time_max > 0.000075):
self.put(0, 0, self.out_ann, [0,
['WARNING: The normal mode presence sample time interval ' +
'(%2.1fus-%2.1fus) should be inside (68.1us, 75.0us).'
% (time_min * 1000000, time_max * 1000000)]])
time_min = float(self.cnt_overdrive_bit) / self.samplerate
time_max = float(self.cnt_overdrive_bit + 1) / self.samplerate
if (time_min < 0.000001) or (time_max > 0.000002):
self.put(0, 0, self.out_ann, [0,
['WARNING: The overdrive mode data sample time interval ' +
'(%2.1fus-%2.1fus) should be inside (1.0us, 2.0us).'
% (time_min * 1000000, time_max * 1000000)]])
time_min = float(self.cnt_overdrive_presence) / self.samplerate
time_max = float(self.cnt_overdrive_presence + 1) / self.samplerate
if (time_min < 0.0000073) or (time_max > 0.000010):
self.put(0, 0, self.out_ann, [0,
['WARNING: The overdrive mode presence sample time interval ' +
'(%2.1fus-%2.1fus) should be inside (7.3us, 10.0us).'
% (time_min*1000000, time_max*1000000)]])
def report(self):
pass
def decode(self, ss, es, data):
for (self.samplenum, (owr, pwr)) in data:
# State machine.
if self.state == 'WAIT FOR FALLING EDGE':
# The start of a cycle is a falling edge.
if owr == 0:
# Save the sample number for the falling edge.
self.fall = self.samplenum
# Go to waiting for sample time.
self.state = 'WAIT FOR DATA SAMPLE'
elif self.state == 'WAIT FOR DATA SAMPLE':
# Sample data bit.
t = self.samplenum - self.fall
if t == self.cnt_bit[self.overdrive]:
self.bit = owr
self.state = 'WAIT FOR DATA SLOT END'
elif self.state == 'WAIT FOR DATA SLOT END':
# A data slot ends in a recovery period, otherwise, this is
# probably a reset.
t = self.samplenum - self.fall
if t == self.cnt_slot[self.overdrive]:
if owr:
self.put(self.fall, self.samplenum, self.out_ann,
[0, ['BIT: %01x' % self.bit]])
self.put(self.fall, self.samplenum, self.out_proto,
['BIT', self.bit])
# Checking the first command to see if overdrive mode
# should be entered.
if self.bit_cnt <= 8:
self.command |= (self.bit << self.bit_cnt)
elif self.bit_cnt == 8 and self.command in [0x3c, 0x69]:
self.put(self.fall, self.cnt_bit[self.overdrive],
self.out_ann,
[0, ['ENTER OVERDRIVE MODE']])
# Increment the bit counter.
self.bit_cnt += 1
# Wait for next slot.
self.state = 'WAIT FOR FALLING EDGE'
else:
# This seems to be a reset slot, wait for its end.
self.state = 'WAIT FOR RISING EDGE'
elif self.state == 'WAIT FOR RISING EDGE':
# The end of a cycle is a rising edge.
if owr:
# Check if this was a reset cycle.
t = self.samplenum - self.fall
if t > self.cnt_normal_reset:
# Save the sample number for the falling edge.
self.rise = self.samplenum
self.state = 'WAIT FOR PRESENCE DETECT'
# Exit overdrive mode.
if self.overdrive:
self.put(self.fall, self.cnt_bit[self.overdrive],
self.out_ann, [0, ['EXIT OVERDRIVE MODE']])
self.overdrive = 0
# Clear command bit counter and data register.
self.bit_cnt = 0
self.command = 0
elif (t > self.cnt_overdrive_reset) and self.overdrive:
# Save the sample number for the falling edge.
self.rise = self.samplenum
self.state = "WAIT FOR PRESENCE DETECT"
# Otherwise this is assumed to be a data bit.
else:
self.state = "WAIT FOR FALLING EDGE"
elif self.state == 'WAIT FOR PRESENCE DETECT':
# Sample presence status.
t = self.samplenum - self.rise
if t == self.cnt_presence[self.overdrive]:
self.present = owr
self.state = 'WAIT FOR RESET SLOT END'
elif self.state == 'WAIT FOR RESET SLOT END':
# A reset slot ends in a long recovery period
t = self.samplenum - self.rise
if t == self.cnt_reset[self.overdrive]:
if owr:
self.put(self.fall, self.samplenum, self.out_ann,
[0, ['RESET/PRESENCE: %s'
% ('False' if self.present else 'True')]])
self.put(self.fall, self.samplenum, self.out_proto,
['RESET/PRESENCE', not self.present])
# Wait for next slot.
self.state = 'WAIT FOR FALLING EDGE'
else:
# This seems to be a reset slot, wait for its end.
self.state = 'WAIT FOR RISING EDGE'
else:
raise Exception('Invalid state: %s' % self.state)
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