2 ## This file is part of the libsigrokdecode project.
4 ## Copyright (C) 2016 Sean Burford <sburford@google.com>
6 ## This program is free software; you can redistribute it and/or modify
7 ## it under the terms of the GNU General Public License as published by
8 ## the Free Software Foundation; either version 2 of the License, or
9 ## (at your option) any later version.
11 ## This program is distributed in the hope that it will be useful,
12 ## but WITHOUT ANY WARRANTY; without even the implied warranty of
13 ## MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 ## GNU General Public License for more details.
16 ## You should have received a copy of the GNU General Public License
17 ## along with this program; if not, see <http://www.gnu.org/licenses/>.
20 import sigrokdecode as srd
22 class SamplerateError(Exception):
25 class Decoder(srd.Decoder):
29 longname = 'Wiegand interface'
30 desc = 'Wiegand interface for electronic entry systems.'
34 tags = ['Embedded/industrial', 'RFID']
36 {'id': 'd0', 'name': 'D0', 'desc': 'Data 0 line'},
37 {'id': 'd1', 'name': 'D1', 'desc': 'Data 1 line'},
40 {'id': 'active', 'desc': 'Data lines active level',
41 'default': 'low', 'values': ('low', 'high')},
42 {'id': 'bitwidth_ms', 'desc': 'Single bit width in milliseconds',
43 'default': 4, 'values': (1, 2, 4, 8, 16, 32)},
50 ('bits', 'Bits', (0,)),
51 ('states', 'Stream states', (1,)),
58 self.samplerate = None
59 self._samples_per_bit = 10
73 'Register output types and verify user supplied decoder values.'
74 self.out_ann = self.register(srd.OUTPUT_ANN)
75 self._active = 1 if self.options['active'] == 'high' else 0
76 self._inactive = 1 - self._active
78 def metadata(self, key, value):
79 'Receive decoder metadata about the data stream.'
80 if key == srd.SRD_CONF_SAMPLERATE:
81 self.samplerate = value
83 ms_per_sample = 1000 * (1.0 / self.samplerate)
84 ms_per_bit = float(self.options['bitwidth_ms'])
85 self._samples_per_bit = int(max(1, int(ms_per_bit / ms_per_sample)))
87 def _update_state(self, state, bit=None):
88 'Update state and bit values when they change.'
89 if self._bit is not None:
90 self._bits.append(self._bit)
91 self.put(self.ss_bit, self.samplenum, self.out_ann,
92 [0, [str(self._bit)]])
94 self.ss_bit = self.samplenum
96 # Set a timeout so that the final bit ends.
97 self.es_bit = self.samplenum + self._samples_per_bit
101 if state != self._state:
103 if self._state == 'data':
104 accum_bits = ''.join(str(x) for x in self._bits)
105 ann = [1, ['%d bits %s' % (len(self._bits), accum_bits),
106 '%d bits' % len(self._bits)]]
107 elif self._state == 'invalid':
108 ann = [1, [self._state]]
110 self.put(self.ss_state, self.samplenum, self.out_ann, ann)
111 self.ss_state = self.samplenum
116 if not self.samplerate:
117 raise SamplerateError('Cannot decode without samplerate.')
119 # TODO: Come up with more appropriate self.wait() conditions.
120 (d0, d1) = self.wait()
122 if d0 == self._d0_prev and d1 == self._d1_prev:
123 if self.es_bit and self.samplenum >= self.es_bit:
124 if (d0, d1) == (self._inactive, self._inactive):
125 self._update_state('idle')
127 self._update_state('invalid')
130 if self._state in (None, 'idle', 'data'):
131 if (d0, d1) == (self._active, self._inactive):
132 self._update_state('data', 0)
133 elif (d0, d1) == (self._inactive, self._active):
134 self._update_state('data', 1)
135 elif (d0, d1) == (self._active, self._active):
136 self._update_state('invalid')
137 elif self._state == 'invalid':
138 # Wait until we see an idle state before leaving invalid.
139 # This prevents inverted lines from being misread.
140 if (d0, d1) == (self._inactive, self._inactive):
141 self._update_state('idle')
143 self._d0_prev, self._d1_prev = d0, d1
146 return '%s: %s D0 %d D1 %d (active on %d), %d samples per bit' % (
147 self.name, self._state, self._d0_prev, self._d1_prev,
148 self._active, self._samples_per_bit)