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Diffstat (limited to 'decoders/onewire_link/onewire_link.py')
| -rw-r--r-- | decoders/onewire_link/onewire_link.py | 223 |
1 files changed, 223 insertions, 0 deletions
diff --git a/decoders/onewire_link/onewire_link.py b/decoders/onewire_link/onewire_link.py new file mode 100644 index 0000000..3236f4d --- /dev/null +++ b/decoders/onewire_link/onewire_link.py @@ -0,0 +1,223 @@ +## +## 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.overdrive = 0 + self.cmd_cnt = 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.out_proto, ['BIT', self.bit]) + # Checking the first command to see if overdrive mode should be entered + if (self.cmd_cnt <= 8): + self.command = self.command | (self.bit << self.cmd_cnt) + elif (self.cmd_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.cmd_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) |