Add a DMX512 protocol decoder

1 files changed, 170 insertions, 0 deletions

diff --git a/decoders/dmx512/pd.py b/decoders/dmx512/pd.py
new file mode 100644
index 0000000..e684b13
--- /dev/null
+++ b/decoders/dmx512/pd.py
@@ -0,0 +1,170 @@
+##
+## This file is part of the libsigrokdecode project.
+##
+## Copyright (C) 2016 Fabian J. Stumpf <sigrok@fabianstumpf.de>
+##
+## 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
+##
+
+import sigrokdecode as srd
+
+class Decoder(srd.Decoder):
+    api_version = 2
+    id = 'dmx512'
+    name = 'DMX512'
+    longname = 'Digital MultipleX 512'
+    desc = 'Professional lighting control protocol.'
+    license = 'gplv2+'
+    inputs = ['logic']
+    outputs = ['dmx512']
+    channels = (
+        {'id': 'dmx', 'name': 'DMX data', 'desc': 'Any DMX data line'},
+    )
+    annotations = (
+        ('bit', 'Bit'),
+        ('break', 'Break'),
+        ('mab', 'Mark after break'),
+        ('startbit', 'Start bit'),
+        ('stopbits', 'Stop bit'),
+        ('startcode', 'Start code'),
+        ('channel', 'Channel'),
+        ('interframe', 'Interframe'),
+        ('interpacket', 'Interpacket'),
+        ('data', 'Data'),
+        ('error', 'Error'),
+    )
+    annotation_rows = (
+        ('name', 'Logical', (1, 2, 5, 6, 7, 8)),
+        ('data', 'Data', (9,)),
+        ('bits', 'Bits', (0, 3, 4)),
+        ('errors', 'Errors', (10,)),
+    )
+
+    def __init__(self):
+        self.samplerate = None
+        self.sample_usec = None
+        self.samplenum = -1
+        self.run_start = -1
+        self.run_bit = 0
+        self.state = 'FIND BREAK'
+
+    def start(self):
+        self.out_ann = self.register(srd.OUTPUT_ANN)
+
+    def metadata(self, key, value):
+        if key == srd.SRD_CONF_SAMPLERATE:
+            self.samplerate = value
+            self.sample_usec = 1 / value * 1000000
+            self.skip_per_bit = int(4 / self.sample_usec)
+
+    def putr(self, data):
+        self.put(self.run_start, self.samplenum, self.out_ann, data)
+
+    def decode(self, ss, es, data):
+        if not self.samplerate:
+            raise SamplerateError('Cannot decode without samplerate.')
+        for (self.samplenum, pins) in data:
+            # Seek for an interval with no state change with a length between
+            # 88 and 1000000 us (BREAK).
+            if self.state == 'FIND BREAK':
+                if self.run_bit == pins[0]:
+                    continue
+                runlen = (self.samplenum - self.run_start) * self.sample_usec
+                if runlen > 88 and runlen < 1000000:
+                    self.putr([1, ['Break']])
+                    self.bit_break = self.run_bit
+                    self.state = 'MARK MAB'
+                    self.channel = 0
+                elif runlen >= 1000000:
+                    # Error condition.
+                    self.putr([10, ['Invalid break length']])
+                self.run_bit = pins[0]
+                self.run_start = self.samplenum
+            # Directly following the BREAK is the MARK AFTER BREAK.
+            elif self.state == 'MARK MAB':
+                if self.run_bit == pins[0]:
+                    continue
+                self.putr([2, ['MAB']])
+                self.state = 'READ BYTE'
+                self.channel = 0
+                self.bit = 0
+                self.aggreg = pins[0]
+                self.run_start = self.samplenum
+            # Mark and read a single transmitted byte
+            # (start bit, 8 data bits, 2 stop bits).
+            elif self.state == 'READ BYTE':
+                self.next_sample = self.run_start + (self.bit + 1) * self.skip_per_bit
+                self.aggreg += pins[0]
+                if self.samplenum != self.next_sample:
+                    continue
+                bit_value = 0 if round(self.aggreg/self.skip_per_bit) == self.bit_break else 1
+
+                if self.bit == 0:
+                    self.byte = 0
+                    self.putr([3, ['Start bit']])
+                    if bit_value != 0:
+                        # (Possibly) invalid start bit, mark but don't fail.
+                        self.put(self.samplenum, self.samplenum,
+                                 self.out_ann, [10, ['Invalid start bit']])
+                elif self.bit >= 9:
+                    self.put(self.samplenum - self.skip_per_bit,
+                        self.samplenum, self.out_ann, [4, ['Stop bit']])
+                    if bit_value != 1:
+                        # Invalid stop bit, mark.
+                        self.put(self.samplenum, self.samplenum,
+                            self.out_ann, [10, ['Invalid stop bit']])
+                        if self.bit == 10:
+                            # On invalid 2nd stop bit, search for new break.
+                            self.run_bit = pins[0]
+                            self.state = 'FIND BREAK'
+                else:
+                    # Label and process one bit.
+                    self.put(self.samplenum - self.skip_per_bit,
+                        self.samplenum, self.out_ann, [0, [str(bit_value)]])
+                    self.byte |= bit_value << (self.bit - 1)
+
+                # Label a complete byte.
+                if self.bit == 10:
+                    if self.channel == 0:
+                        d = [5, ['Start code']]
+                    else:
+                        d = [6, ['Channel ' + str(self.channel)]]
+                    self.put(self.run_start, self.next_sample, self.out_ann, d)
+                    self.put(self.run_start + self.skip_per_bit,
+                        self.next_sample - 2 * self.skip_per_bit,
+                        self.out_ann, [9, [str(self.byte) + ' / ' + \
+                        str(hex(self.byte))]])
+                    # Continue by scanning the IFT.
+                    self.channel += 1
+                    self.run_start = self.samplenum
+                    self.run_bit = pins[0]
+                    self.state = 'MARK IFT'
+
+                self.aggreg = pins[0]
+                self.bit += 1
+            # Mark the INTERFRAME-TIME between bytes / INTERPACKET-TIME between packets.
+            elif self.state == 'MARK IFT':
+                if self.run_bit == pins[0]:
+                    continue
+                if self.channel > 512:
+                    self.putr([8, ['Interpacket']])
+                    self.state = 'FIND BREAK'
+                    self.run_bit = pins[0]
+                    self.run_start = self.samplenum
+                else:
+                    self.putr([7, ['Interframe']])
+                    self.state = 'READ BYTE'
+                    self.bit = 0
+                    self.run_start = self.samplenum