Implement new 1-Wire link decoder using time ranges

Rewrite of the 1-Wire link decoder.

Existing outputs are kept and new warnings are added.

Instead of sampling at fixed user defined time, time ranges as
specified by the "Book of iButton Standards" are used.

The user does not have to tweak the timing values anymore.

Overdrive speed is detected automatically.

This fixes bugs #666 and #926.

2 files changed, 259 insertions, 206 deletions

diff --git a/decoders/onewire_link/__init__.py b/decoders/onewire_link/__init__.py
index 28b0194..69b570f 100644
--- a/decoders/onewire_link/__init__.py
+++ b/decoders/onewire_link/__init__.py
@@ -2,6 +2,7 @@
 ## This file is part of the libsigrokdecode project.
 ##
 ## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.de>
+## 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
@@ -39,29 +40,17 @@ overdrive communication speed. The following minimal values should be used:
 Channels:
 1-Wire requires a single signal, but some master implementations might have a
 separate signal used to deliver power to the bus during temperature conversion
-as an example. This power signal is currently not used.
+as an example.
 
  - owr (1-Wire signal line)
- - pwr (optional, dedicated power supply pin)
 
 Options:
-1-Wire is an asynchronous protocol, so the decoder must know the samplerate.
-The timing for sampling bits, presence, and reset is calculated by the decoder,
-but in case the user wishes to use different values, it is possible to
-configure the following timing values (number of samplerate periods):
+1-Wire is an asynchronous protocol with fixed timing values, so the decoder must
+know the samplerate.
+Two speeds are available: normal and overdrive. The decoder detects when
+switching from one to another but the user can set which to start decoding with:
 
- - overdrive              (if active the decoder will be prepared for overdrive)
- - cnt_normal_bit         (time for normal mode sample bit)
- - cnt_normal_slot        (time for normal mode data slot)
- - cnt_normal_presence    (time for normal mode sample presence)
- - cnt_normal_reset       (time for normal mode reset)
- - cnt_overdrive_bit      (time for overdrive mode sample bit)
- - cnt_overdrive_slot     (time for overdrive mode data slot)
- - cnt_overdrive_presence (time for overdrive mode sample presence)
- - cnt_overdrive_reset    (time for overdrive mode reset)
-
-These options should be configured only on very rare cases and the user should
-read the decoder source code to understand them correctly.
+ - overdrive (to decode starting with overdrive speed)
 '''
 
 from .pd import Decoder
diff --git a/decoders/onewire_link/pd.py b/decoders/onewire_link/pd.py
index 3974c45..d33d6d0 100644
--- a/decoders/onewire_link/pd.py
+++ b/decoders/onewire_link/pd.py
@@ -1,7 +1,7 @@
 ##
 ## This file is part of the libsigrokdecode project.
 ##
-## Copyright (C) 2012 Iztok Jeras <iztok.jeras@gmail.com>
+## 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
@@ -22,8 +22,74 @@ 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
+    api_version = 2
     id = 'onewire_link'
     name = '1-Wire link layer'
     longname = '1-Wire serial communication bus (link layer)'
@@ -34,36 +100,16 @@ class Decoder(srd.Decoder):
     channels = (
         {'id': 'owr', 'name': 'OWR', 'desc': '1-Wire signal line'},
     )
-    optional_channels = (
-        {'id': 'pwr', 'name': 'PWR', 'desc': '1-Wire power supply pin'},
-    )
     options = (
-        {'id': 'overdrive',
-            'desc': 'Overdrive mode', 'default': 'no', 'values': ('yes', 'no')},
-        # Time options (specified in microseconds):
-        {'id': 'cnt_normal_bit',
-            'desc': 'Normal mode sample bit time (μs)', 'default': 15},
-        {'id': 'cnt_normal_slot',
-            'desc': 'Normal mode data slot time (μs)', 'default': 60},
-        {'id': 'cnt_normal_presence',
-            'desc': 'Normal mode sample presence time (μs)', 'default': 75},
-        {'id': 'cnt_normal_reset',
-            'desc': 'Normal mode reset time (μs)', 'default': 480},
-        {'id': 'cnt_overdrive_bit',
-            'desc': 'Overdrive mode sample bit time (μs)', 'default': 2},
-        {'id': 'cnt_overdrive_slot',
-            'desc': 'Overdrive mode data slot time (μs)', 'default': 7.3},
-        {'id': 'cnt_overdrive_presence',
-            'desc': 'Overdrive mode sample presence time (μs)', 'default': 10},
-        {'id': 'cnt_overdrive_reset',
-            'desc': 'Overdrive mode reset time (μs)', 'default': 48},
+        {'id': 'overdrive', 'desc': 'Start in overdrive speed',
+            'default': 'no', 'values': ('yes', 'no')},
     )
     annotations = (
         ('bit', 'Bit'),
         ('warnings', 'Warnings'),
         ('reset', 'Reset'),
         ('presence', 'Presence'),
-        ('overdrive', 'Overdrive mode notifications'),
+        ('overdrive', 'Overdrive speed notifications'),
     )
     annotation_rows = (
         ('bits', 'Bits', (0, 2, 3)),
@@ -71,43 +117,25 @@ class Decoder(srd.Decoder):
         ('warnings', 'Warnings', (1,)),
     )
 
-    def putm(self, data):
-        self.put(0, 0, self.out_ann, data)
-
-    def putpb(self, data):
-        self.put(self.fall, self.samplenum, self.out_python, data)
-
-    def putb(self, data):
-        self.put(self.fall, self.samplenum, self.out_ann, data)
-
-    def putx(self, data):
-        self.put(self.fall, self.cnt_bit[self.overdrive], 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 __init__(self):
         self.samplerate = None
-        self.state = 'WAIT FOR FALLING EDGE'
+        self.samplenum = 0
+        self.state = 'INITIAL'
         self.present = 0
         self.bit = 0
-        self.bit_cnt = 0
+        self.bit_count = -1
         self.command = 0
-        self.overdrive = 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.initial_pins = [1, 1]
+        self.overdrive = (self.options['overdrive'] == 'yes')
+        self.fall = 0
+        self.rise = 0
+        self.bit_count = -1
 
     def checks(self):
         # Check if samplerate is appropriate.
@@ -126,155 +154,191 @@ class Decoder(srd.Decoder):
                 self.putm([1, ['Sampling rate is suggested to be above ' +
                                '1MHz for proper normal mode decoding.']])
 
-        # 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.putm([1, ['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.putm([1, ['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.putm([1, ['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.putm([1, ['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 metadata(self, key, value):
         if key != srd.SRD_CONF_SAMPLERATE:
             return
         self.samplerate = value
 
-        # The default 1-Wire time base is 30us. This is used to calculate
-        # sampling times.
-        samplerate = float(self.samplerate)
-
-        x = float(self.options['cnt_normal_bit']) / 1000000.0
-        self.cnt_normal_bit = int(samplerate * x) - 1
-        x = float(self.options['cnt_normal_slot']) / 1000000.0
-        self.cnt_normal_slot = int(samplerate * x) - 1
-        x = float(self.options['cnt_normal_presence']) / 1000000.0
-        self.cnt_normal_presence = int(samplerate * x) - 1
-        x = float(self.options['cnt_normal_reset']) / 1000000.0
-        self.cnt_normal_reset = int(samplerate * x) - 1
-        x = float(self.options['cnt_overdrive_bit']) / 1000000.0
-        self.cnt_overdrive_bit = int(samplerate * x) - 1
-        x = float(self.options['cnt_overdrive_slot']) / 1000000.0
-        self.cnt_overdrive_slot = int(samplerate * x) - 1
-        x = float(self.options['cnt_overdrive_presence']) / 1000000.0
-        self.cnt_overdrive_presence = int(samplerate * x) - 1
-        x = float(self.options['cnt_overdrive_reset']) / 1000000.0
-        self.cnt_overdrive_reset = int(samplerate * x) - 1
-
-        # 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]
-
-    def decode(self):
+    def decode(self, ss, es, data):
         if not self.samplerate:
             raise SamplerateError('Cannot decode without samplerate.')
-        self.checks()
-        while True:
+        for (self.samplenum, (owr,)) in data:
+            if self.samplenum == 0:
+                self.checks()
+
             # State machine.
-            if self.state == 'WAIT FOR FALLING EDGE':
-                # The start of a cycle is a falling edge on OWR.
-                self.wait({0: 'f'})
-                # Save the sample number for the falling edge.
+            if self.state == 'INITIAL': # Unknown initial state.
+                # Wait until we reach the idle high state.
+                if owr == 0:
+                    continue
+                self.rise = self.samplenum
+                self.state = 'IDLE'
+            elif self.state == 'IDLE': # Idle high state.
+                # Wait for falling edge.
+                if owr != 0:
+                    continue
                 self.fall = self.samplenum
-                self.state = 'WAIT FOR DATA SAMPLE'
-            elif self.state == 'WAIT FOR DATA SAMPLE':
-                # Sample data bit.
-                t = self.fall + self.cnt_bit[self.overdrive]
-                self.bit, pwr = self.wait({'skip': t - self.samplenum})
-                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.fall + self.cnt_slot[self.overdrive]
-                owr, pwr = self.wait({'skip': t - 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.put(self.fall, self.rise, self.out_ann,
+                        [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.
                 if owr == 0:
-                    # This seems to be a reset slot, wait for its end.
-                    self.state = 'WAIT FOR RISING EDGE'
                     continue
-
-                self.putb([0, ['Bit: %d' % self.bit, '%d' % self.bit]])
-                self.putpb(['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.putx([4, ['Entering overdrive mode', 'Overdrive on']])
-                # Increment the bit counter.
-                self.bit_cnt += 1
-                # Wait for next slot.
-                self.state = 'WAIT FOR FALLING EDGE'
-            elif self.state == 'WAIT FOR RISING EDGE':
-                # The end of a cycle is a rising edge.
-                self.wait({0: 'r'})
-
-                # Check if this was a reset cycle.
-                t = self.samplenum - self.fall
-                if t > self.cnt_normal_reset:
-                    # Save the sample number for the rising edge.
-                    self.rise = self.samplenum
-                    self.putfr([2, ['Reset', 'Rst', 'R']])
-                    self.state = 'WAIT FOR PRESENCE DETECT'
-                    # Exit overdrive mode.
+                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.put(self.fall, self.rise, self.out_ann,
+                            [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.putx([4, ['Exiting overdrive mode', 'Overdrive off']])
-                        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 rising edge.
-                    self.rise = self.samplenum
-                    self.putfr([2, ['Reset', 'Rst', 'R']])
-                    self.state = 'WAIT FOR PRESENCE DETECT'
-                # Otherwise this is assumed to be a data bit.
+                        self.put(self.fall, self.rise, self.out_ann,
+                            [4, ['Exiting overdrive mode', 'Overdrive off']])
+                    self.overdrive = False
+                    self.put(self.fall, self.rise, self.out_ann,
+                        [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.put(self.fall, self.rise, self.out_ann,
+                        [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.put(self.fall, self.rise, self.out_ann,
+                            [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:
-                    self.state = 'WAIT FOR FALLING EDGE'
-            elif self.state == 'WAIT FOR PRESENCE DETECT':
-                # Sample presence status.
-                t = self.rise + self.cnt_presence[self.overdrive]
-                owr, pwr = self.wait({'skip': t - self.samplenum})
-                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.rise + self.cnt_reset[self.overdrive]
-                owr, pwr = self.wait({'skip': t - self.samplenum})
-
+                    # Timing outside of known states.
+                    self.put(self.fall, self.rise, self.out_ann,
+                        [1, ['Erroneous signal', 'Error', 'Err', 'E']])
+                    self.state = 'IDLE'
+            elif self.state == 'PRESENCE DETECT HIGH': # Wait for slave presence signal.
+                # Calculate time since rising edge.
+                time = ((self.samplenum - self.rise) / self.samplerate) * 1000000.0
+                if owr != 0 and time < timing['PDH']['max'][self.overdrive]:
+                    continue
+                elif owr == 0: # Presence detected.
+                    if time < timing['PDH']['min'][self.overdrive]:
+                        self.put(self.rise, self.samplenum, self.out_ann,
+                            [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.put(self.rise, self.samplenum, self.out_ann,
+                        [3, ['Presence: false', 'Presence', 'Pres', 'P']])
+                    self.put(self.rise, self.samplenum, self.out_python,
+                        ['RESET/PRESENCE', False])
+                    self.state = 'IDLE'
+            elif self.state == 'PRESENCE DETECT LOW': # Slave presence signalled.
+                # Wait for end of presence signal (on rising edge).
                 if owr == 0:
-                    # This seems to be a reset slot, wait for its end.
-                    self.state = 'WAIT FOR RISING EDGE'
                     continue
-
-                p = 'false' if self.present else 'true'
-                self.putrs([3, ['Presence: %s' % p, 'Presence', 'Pres', 'P']])
-                self.putprs(['RESET/PRESENCE', not self.present])
-
-                # Wait for next slot.
-                self.state = 'WAIT FOR FALLING EDGE'
+                # Calculate time since start of presence signal.
+                time = ((self.samplenum - self.fall) / self.samplerate) * 1000000.0
+                if time < timing['PDL']['min'][self.overdrive]:
+                    self.put(self.fall, self.samplenum, self.out_ann,
+                        [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.put(self.fall, self.samplenum, self.out_ann,
+                        [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.
+                # Calculate time since falling edge.
+                time = ((self.samplenum - self.fall) / self.samplerate) * 1000000.0
+                if owr != 0 and time < timing['SLOT']['min'][self.overdrive]:
+                    continue
+                elif owr == 0: # Low detected before end of slot.
+                    # Warn about irregularity.
+                    self.put(self.fall, self.samplenum, self.out_ann,
+                        [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.put(self.fall, self.samplenum, self.out_ann,
+                        [0, ['Bit: %d' % self.bit, '%d' % self.bit]])
+                    self.put(self.fall, self.samplenum, self.out_python,
+                        ['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 end of presence detect.
+                # Calculate time since falling edge.
+                time = ((self.samplenum - self.rise) / self.samplerate) * 1000000.0
+                if owr != 0 and time < timing['RSTH']['min'][self.overdrive]:
+                    continue
+                elif owr == 0: # Low detected before end of presence detect.
+                    # Warn about irregularity.
+                    self.put(self.fall, self.samplenum, self.out_ann,
+                        [1, ['Presence detect not long enough',
+                        'Presence detect too short',
+                        'RTSH < ' + str(timing['RSTH']['min'][self.overdrive])]])
+                    # Inform about presence detected.
+                    self.put(self.rise, self.samplenum, self.out_ann,
+                        [3, ['Slave presence detected', 'Slave present',
+                        'Present', 'P']])
+                    self.put(self.rise, self.samplenum, self.out_python,
+                        ['RESET/PRESENCE', True])
+                    self.fall = self.samplenum
+                    self.state = 'LOW'
+                else: # End of time slot.
+                    # Inform about presence detected.
+                    self.put(self.rise, self.samplenum, self.out_ann,
+                        [3, ['Presence: true', 'Presence', 'Pres', 'P']])
+                    self.put(self.rise, self.samplenum, self.out_python,
+                        ['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'