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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 link layer protocol decoder
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'
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],
'cnt_normal_bit' : ['Time (in samplerate periods) for normal mode sample bit' , 0],
'cnt_normal_presence' : ['Time (in samplerate periods) for normal mode sample presence', 0],
'cnt_normal_reset' : ['Time (in samplerate periods) for normal mode reset' , 0],
'cnt_overdrive_bit' : ['Time (in samplerate periods) for overdrive mode sample bit' , 0],
'cnt_overdrive_presence': ['Time (in samplerate periods) for overdrive mode sample presence', 0],
'cnt_overdrive_reset' : ['Time (in samplerate periods) for overdrive mode reset' , 0],
}
annotations = [
['Link', 'Link layer events (reset, presence, bit slots)'],
]
def __init__(self, **kwargs):
# Common variables
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')
# check if samplerate is appropriate
self.samplerate = metadata['samplerate']
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.
if (self.options['cnt_normal_bit']):
self.cnt_normal_bit = self.options['cnt_normal_bit']
else:
self.cnt_normal_bit = int(float(self.samplerate) * 0.000015) - 1 # 15ns
if (self.options['cnt_normal_presence']):
self.cnt_normal_presence = self.options['cnt_normal_presence']
else:
self.cnt_normal_presence = int(float(self.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(float(self.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(float(self.samplerate) * 0.000002) - 1 # 2ns
if (self.options['cnt_overdrive_presence']):
self.cnt_overdrive_presence = self.options['cnt_overdrive_presence']
else:
self.cnt_overdrive_presence = int(float(self.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(float(self.samplerate) * 0.000048) - 1 # 48ns
# calculating the slot size
self.cnt_normal_slot = int(float(self.samplerate) * 0.000060) - 1 # 60ns
self.cnt_overdrive_slot = int(float(self.samplerate) * 0.000006) - 1 # 6ns
# 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
if (self.samplenum - self.fall == self.cnt_bit[self.overdrive]):
self.bit = owr & 0x1
if (self.bit): self.state = 'WAIT FOR FALLING EDGE'
else : self.state = 'WAIT FOR RISING EDGE'
self.put(self.fall, self.cnt_bit[self.overdrive], self.out_ann, [0, ['BIT: %01x' % self.bit]])
self.put(self.fall, self.cnt_bit[self.overdrive], 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.command | (self.bit << self.bit_cnt)
elif (self.bit_cnt == 8):
if (self.command in [0x3c, 0x69]):
self.put(self.fall, self.cnt_bit[self.overdrive], self.out_ann, [0, ['ENTER OVERDRIVE MODE']])
# incrementing the bit counter
self.bit_cnt += 1
elif self.state == 'WAIT FOR RISING EDGE':
# The end of a cycle is a rising edge.
if (owr == 1):
# Check if this was a reset cycle
if (self.samplenum - self.fall > self.cnt_normal_reset):
# Save the sample number for the falling edge.
self.rise = self.samplenum
self.state = "WAIT FOR PRESENCE DETECT"
self.put(self.fall, self.rise, self.out_ann, [0, ['RESET']])
self.put(self.fall, self.rise, self.out_proto, ['RESET', 0])
# Reset the timer.
self.fall = self.samplenum
# Exit overdrive mode
self.put(self.fall, self.cnt_bit[self.overdrive], self.out_ann, [0, ['EXIT OVERDRIVE MODE']])
self.overdrive = 0
self.bit_cnt = 0
self.command = 0
elif ((self.samplenum - self.fall > 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"
self.put(self.fall, self.rise, self.out_ann, [0, ['RESET']])
self.put(self.fall, self.rise, self.out_proto, ['RESET', 0])
# Reset the timer.
self.fall = self.samplenum
# 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
if (self.samplenum - self.rise == self.cnt_presence[self.overdrive]):
self.present = owr & 0x1
# Save the sample number for the falling edge.
if not (self.present) : self.fall = self.samplenum
# create presence detect event
if (self.present) : self.state = 'WAIT FOR FALLING EDGE'
else : self.state = 'WAIT FOR RISING EDGE'
self.put(self.samplenum, 0, self.out_ann, [0, ['PRESENCE: ' + "False" if self.present else "True"]])
self.put(self.samplenum, 0, self.out_proto, ['PRESENCE', self.present])
else:
raise Exception('Invalid state: %d' % self.state)
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