##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2017 Kevin Redon <kingkevin@cuvoodoo.info>
##
## 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 sigrokdecode as srd
class SamplerateError(Exception):
pass
# Timing values in us for the signal at regular and overdrive speed.
timing = {
'RSTL': {
'min': {
False: 480.0,
True: 48.0,
},
'max': {
False: 960.0,
True: 80.0,
},
},
'RSTH': {
'min': {
False: 480.0,
True: 48.0,
},
},
'PDH': {
'min': {
False: 15.0,
True: 2.0,
},
'max': {
False: 60.0,
True: 6.0,
},
},
'PDL': {
'min': {
False: 60.0,
True: 8.0,
},
'max': {
False: 240.0,
True: 24.0,
},
},
'SLOT': {
'min': {
False: 60.0,
True: 6.0,
},
'max': {
False: 120.0,
True: 16.0,
},
},
'REC': {
'min': {
False: 1.0,
True: 1.0,
},
},
'LOWR': {
'min': {
False: 1.0,
True: 1.0,
},
'max': {
False: 15.0,
True: 2.0,
},
},
}
class Decoder(srd.Decoder):
api_version = 3
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']
tags = ['Embedded/industrial']
channels = (
{'id': 'owr', 'name': 'OWR', 'desc': '1-Wire signal line'},
)
options = (
{'id': 'overdrive', 'desc': 'Start in overdrive speed',
'default': 'no', 'values': ('yes', 'no')},
)
annotations = (
('bit', 'Bit'),
('warning', 'Warning'),
('reset', 'Reset'),
('presence', 'Presence'),
('overdrive', 'Overdrive speed notification'),
)
annotation_rows = (
('bits', 'Bits', (0, 2, 3)),
('info', 'Info', (4,)),
('warnings', 'Warnings', (1,)),
)
def __init__(self):
self.reset()
def reset(self):
self.samplerate = None
self.state = 'INITIAL'
self.present = 0
self.bit = 0
self.bit_count = -1
self.command = 0
self.overdrive = False
self.fall = 0
self.rise = 0
def start(self):
self.out_python = self.register(srd.OUTPUT_PYTHON)
self.out_ann = self.register(srd.OUTPUT_ANN)
self.overdrive = (self.options['overdrive'] == 'yes')
self.fall = 0
self.rise = 0
self.bit_count = -1
def putm(self, data):
self.put(0, 0, self.out_ann, data)
def putpfs(self, data):
self.put(self.fall, self.samplenum, self.out_python, data)
def putfs(self, data):
self.put(self.fall, self.samplenum, self.out_ann, data)
def putfr(self, data):
self.put(self.fall, self.rise, self.out_ann, data)
def putprs(self, data):
self.put(self.rise, self.samplenum, self.out_python, data)
def putrs(self, data):
self.put(self.rise, self.samplenum, self.out_ann, data)
def checks(self):
# Check if samplerate is appropriate.
if self.options['overdrive'] == 'yes':
if self.samplerate < 2000000:
self.putm([1, ['Sampling rate is too low. Must be above ' +
'2MHz for proper overdrive mode decoding.']])
elif self.samplerate < 5000000:
self.putm([1, ['Sampling rate is suggested to be above 5MHz ' +
'for proper overdrive mode decoding.']])
else:
if self.samplerate < 400000:
self.putm([1, ['Sampling rate is too low. Must be above ' +
'400kHz for proper normal mode decoding.']])
elif self.samplerate < 1000000:
self.putm([1, ['Sampling rate is suggested to be above ' +
'1MHz for proper normal mode decoding.']])
def metadata(self, key, value):
if key != srd.SRD_CONF_SAMPLERATE:
return
self.samplerate = value
def wait_falling_timeout(self, start, t):
# Wait until either a falling edge is seen, and/or the specified
# number of samples have been skipped (i.e. time has passed).
cnt = int((t[self.overdrive] / 1000000.0) * self.samplerate)
samples_to_skip = (start + cnt) - self.samplenum
samples_to_skip = samples_to_skip if (samples_to_skip > 0) else 0
return self.wait([{0: 'f'}, {'skip': samples_to_skip}])
def decode(self):
if not self.samplerate:
raise SamplerateError('Cannot decode without samplerate.')
self.checks()
while True:
# State machine.
if self.state == 'INITIAL': # Unknown initial state.
# Wait until we reach the idle high state.
self.wait({0: 'h'})
self.rise = self.samplenum
self.state = 'IDLE'
elif self.state == 'IDLE': # Idle high state.
# Wait for falling edge.
self.wait({0: 'f'})
self.fall = self.samplenum
# Get time since last rising edge.
time = ((self.fall - self.rise) / self.samplerate) * 1000000.0
if self.rise > 0 and \
time < timing['REC']['min'][self.overdrive]:
self.putfr([1, ['Recovery time not long enough'
'Recovery too short',
'REC < ' + str(timing['REC']['min'][self.overdrive])]])
# A reset pulse or slot can start on a falling edge.
self.state = 'LOW'
# TODO: Check minimum recovery time.
elif self.state == 'LOW': # Reset pulse or slot.
# Wait for rising edge.
self.wait({0: 'r'})
self.rise = self.samplenum
# Detect reset or slot base on timing.
time = ((self.rise - self.fall) / self.samplerate) * 1000000.0
if time >= timing['RSTL']['min'][False]: # Normal reset pulse.
if time > timing['RSTL']['max'][False]:
self.putfr([1, ['Too long reset pulse might mask interrupt ' +
'signalling by other devices',
'Reset pulse too long',
'RST > ' + str(timing['RSTL']['max'][False])]])
# Regular reset pulse clears overdrive speed.
if self.overdrive:
self.putfr([4, ['Exiting overdrive mode', 'Overdrive off']])
self.overdrive = False
self.putfr([2, ['Reset', 'Rst', 'R']])
self.state = 'PRESENCE DETECT HIGH'
elif self.overdrive == True and \
time >= timing['RSTL']['min'][self.overdrive] and \
time < timing['RSTL']['max'][self.overdrive]:
# Overdrive reset pulse.
self.putfr([2, ['Reset', 'Rst', 'R']])
self.state = 'PRESENCE DETECT HIGH'
elif time < timing['SLOT']['max'][self.overdrive]:
# Read/write time slot.
if time < timing['LOWR']['min'][self.overdrive]:
self.putfr([1, ['Low signal not long enough',
'Low too short',
'LOW < ' + str(timing['LOWR']['min'][self.overdrive])]])
if time < timing['LOWR']['max'][self.overdrive]:
self.bit = 1 # Short pulse is a 1 bit.
else:
self.bit = 0 # Long pulse is a 0 bit.
# Wait for end of slot.
self.state = 'SLOT'
else:
# Timing outside of known states.
self.putfr([1, ['Erroneous signal', 'Error', 'Err', 'E']])
self.state = 'IDLE'
elif self.state == 'PRESENCE DETECT HIGH': # Wait for slave presence signal.
# Wait for a falling edge and/or presence detect signal.
self.wait_falling_timeout(self.rise, timing['PDH']['max'])
# Calculate time since rising edge.
time = ((self.samplenum - self.rise) / self.samplerate) * 1000000.0
if self.matched[0] and not self.matched[1]:
# Presence detected.
if time < timing['PDH']['min'][self.overdrive]:
self.putrs([1, ['Presence detect signal is too early',
'Presence detect too early',
'PDH < ' + str(timing['PDH']['min'][self.overdrive])]])
self.fall = self.samplenum
self.state = 'PRESENCE DETECT LOW'
else: # No presence detected.
self.putrs([3, ['Presence: false', 'Presence', 'Pres', 'P']])
self.putprs(['RESET/PRESENCE', False])
self.state = 'IDLE'
elif self.state == 'PRESENCE DETECT LOW': # Slave presence signalled.
# Wait for end of presence signal (on rising edge).
self.wait({0: 'r'})
# Calculate time since start of presence signal.
time = ((self.samplenum - self.fall) / self.samplerate) * 1000000.0
if time < timing['PDL']['min'][self.overdrive]:
self.putfs([1, ['Presence detect signal is too short',
'Presence detect too short',
'PDL < ' + str(timing['PDL']['min'][self.overdrive])]])
elif time > timing['PDL']['max'][self.overdrive]:
self.putfs([1, ['Presence detect signal is too long',
'Presence detect too long',
'PDL > ' + str(timing['PDL']['max'][self.overdrive])]])
if time > timing['RSTH']['min'][self.overdrive]:
self.rise = self.samplenum
# Wait for end of presence detect.
self.state = 'PRESENCE DETECT'
# End states (for additional checks).
if self.state == 'SLOT': # Wait for end of time slot.
# Wait for a falling edge and/or end of timeslot.
self.wait_falling_timeout(self.fall, timing['SLOT']['min'])
if self.matched[0] and not self.matched[1]:
# Low detected before end of slot.
self.putfs([1, ['Time slot not long enough',
'Slot too short',
'SLOT < ' + str(timing['SLOT']['min'][self.overdrive])]])
# Don't output invalid bit.
self.fall = self.samplenum
self.state = 'LOW'
else: # End of time slot.
# Output bit.
self.putfs([0, ['Bit: %d' % self.bit, '%d' % self.bit]])
self.putpfs(['BIT', self.bit])
# Save command bits.
if self.bit_count >= 0:
self.command += (self.bit << self.bit_count)
self.bit_count += 1
# Check for overdrive ROM command.
if self.bit_count >= 8:
if self.command == 0x3c or self.command == 0x69:
self.overdrive = True
self.put(self.samplenum, self.samplenum,
self.out_ann,
[4, ['Entering overdrive mode', 'Overdrive on']])
self.bit_count = -1
self.state = 'IDLE'
if self.state == 'PRESENCE DETECT':
# Wait for a falling edge and/or end of presence detect.
self.wait_falling_timeout(self.rise, timing['RSTH']['min'])
if self.matched[0] and not self.matched[1]:
# Low detected before end of presence detect.
self.putfs([1, ['Presence detect not long enough',
'Presence detect too short',
'RTSH < ' + str(timing['RSTH']['min'][self.overdrive])]])
# Inform about presence detected.
self.putrs([3, ['Slave presence detected', 'Slave present',
'Present', 'P']])
self.putprs(['RESET/PRESENCE', True])
self.fall = self.samplenum
self.state = 'LOW'
else: # End of time slot.
# Inform about presence detected.
self.putrs([3, ['Presence: true', 'Presence', 'Pres', 'P']])
self.putprs(['RESET/PRESENCE', True])
self.rise = self.samplenum
# Start counting the first 8 bits to get the ROM command.
self.bit_count = 0
self.command = 0
self.state = 'IDLE'