2 ## This file is part of the libsigrokdecode project.
4 ## Copyright (C) 2012-2013 Uwe Hermann <uwe@hermann-uwe.de>
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, write to the Free Software
18 ## Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
21 # DCF77 protocol decoder
23 import sigrokdecode as srd
26 # Return the specified BCD number (max. 8 bits) as integer.
28 return (b & 0x0f) + ((b >> 4) * 10)
30 class Decoder(srd.Decoder):
34 longname = 'DCF77 time protocol'
35 desc = 'European longwave time signal (77.5kHz carrier signal).'
40 {'id': 'data', 'name': 'DATA', 'desc': 'DATA line'},
43 {'id': 'pon', 'name': 'PON', 'desc': 'Power on'},
47 ['Text', 'Human-readable text'],
48 ['Warnings', 'Human-readable warnings'],
51 def __init__(self, **kwargs):
52 self.state = 'WAIT FOR RISING EDGE'
58 self.bit_start_old = 0
60 self.bitcount = 0 # Counter for the DCF77 bits (0..58)
61 self.dcf77_bitnumber_is_known = 0
63 def start(self, metadata):
64 self.samplerate = metadata['samplerate']
65 # self.out_proto = self.add(srd.OUTPUT_PROTO, 'dcf77')
66 self.out_ann = self.add(srd.OUTPUT_ANN, 'dcf77')
72 self.put(self.bit_start, self.bit_end, self.out_ann, data)
74 # TODO: Which range to use? Only the 100ms/200ms or full second?
75 def handle_dcf77_bit(self, bit):
78 # Create one annotation for each DCF77 bit (containing the 0/1 value).
79 # Use 'Unknown DCF77 bit x: val' if we're not sure yet which of the
80 # 0..58 bits it is (because we haven't seen a 'new minute' marker yet).
81 # Otherwise, use 'DCF77 bit x: val'.
82 s = '' if self.dcf77_bitnumber_is_known else 'Unknown '
83 self.putx([0, ['%sDCF77 bit %d: %d' % (s, c, bit)]])
85 # If we're not sure yet which of the 0..58 DCF77 bits we have, return.
86 # We don't want to decode bogus data.
87 if not self.dcf77_bitnumber_is_known:
90 # Output specific "decoded" annotations for the respective DCF77 bits.
92 # Start of minute: DCF bit 0.
94 self.putx([0, ['Start of minute (always 0)']])
96 self.putx([0, ['ERROR: Start of minute != 0']])
97 elif c in range(1, 14 + 1):
98 # Special bits (civil warnings, weather forecast): DCF77 bits 1-14.
102 self.tmp |= (bit << (c - 1))
104 self.putx([0, ['Special bits: %s' % bin(self.tmp)]])
106 s = '' if (bit == 1) else 'not '
107 self.putx([0, ['Call bit is %sset' % s]])
108 # TODO: Previously this bit indicated use of the backup antenna.
110 s = '' if (bit == 1) else 'not '
111 self.putx([0, ['Summer time announcement %sactive' % s]])
113 s = '' if (bit == 1) else 'not '
114 self.putx([0, ['CEST is %sin effect' % s]])
116 s = '' if (bit == 1) else 'not '
117 self.putx([0, ['CET is %sin effect' % s]])
119 s = '' if (bit == 1) else 'not '
120 self.putx([0, ['Leap second announcement %sactive' % s]])
122 # Start of encoded time: DCF bit 20.
124 self.putx([0, ['Start of encoded time (always 1)']])
126 self.putx([0, ['ERROR: Start of encoded time != 1']])
127 elif c in range(21, 27 + 1):
128 # Minutes (0-59): DCF77 bits 21-27 (BCD format).
132 self.tmp |= (bit << (c - 21))
134 self.putx([0, ['Minutes: %d' % bcd2int(self.tmp)]])
136 # Even parity over minute bits (21-28): DCF77 bit 28.
137 self.tmp |= (bit << (c - 21))
138 parity = bin(self.tmp).count('1')
139 s = 'OK' if ((parity % 2) == 0) else 'INVALID!'
140 self.putx([0, ['Minute parity: %s' % s]])
141 elif c in range(29, 34 + 1):
142 # Hours (0-23): DCF77 bits 29-34 (BCD format).
146 self.tmp |= (bit << (c - 29))
148 self.putx([0, ['Hours: %d' % bcd2int(self.tmp)]])
150 # Even parity over hour bits (29-35): DCF77 bit 35.
151 self.tmp |= (bit << (c - 29))
152 parity = bin(self.tmp).count('1')
153 s = 'OK' if ((parity % 2) == 0) else 'INVALID!'
154 self.putx([0, ['Hour parity: %s' % s]])
155 elif c in range(36, 41 + 1):
156 # Day of month (1-31): DCF77 bits 36-41 (BCD format).
160 self.tmp |= (bit << (c - 36))
162 self.putx([0, ['Day: %d' % bcd2int(self.tmp)]])
163 elif c in range(42, 44 + 1):
164 # Day of week (1-7): DCF77 bits 42-44 (BCD format).
165 # A value of 1 means Monday, 7 means Sunday.
169 self.tmp |= (bit << (c - 42))
171 d = bcd2int(self.tmp)
172 dn = calendar.day_name[d - 1] # day_name[0] == Monday
173 self.putx([0, ['Day of week: %d (%s)' % (d, dn)]])
174 elif c in range(45, 49 + 1):
175 # Month (1-12): DCF77 bits 45-49 (BCD format).
179 self.tmp |= (bit << (c - 45))
181 m = bcd2int(self.tmp)
182 mn = calendar.month_name[m] # month_name[1] == January
183 self.putx([0, ['Month: %d (%s)' % (m, mn)]])
184 elif c in range(50, 57 + 1):
185 # Year (0-99): DCF77 bits 50-57 (BCD format).
189 self.tmp |= (bit << (c - 50))
191 self.putx([0, ['Year: %d' % bcd2int(self.tmp)]])
193 # Even parity over date bits (36-58): DCF77 bit 58.
194 self.tmp |= (bit << (c - 50))
195 parity = bin(self.tmp).count('1')
196 s = 'OK' if ((parity % 2) == 0) else 'INVALID!'
197 self.putx([0, ['Date parity: %s' % s]])
199 raise Exception('Invalid DCF77 bit: %d' % c)
201 def decode(self, ss, es, data):
202 for (self.samplenum, pins) in data:
204 # Ignore identical samples early on (for performance reasons).
205 if self.oldpins == pins:
207 self.oldpins, (val, pon) = pins, pins
209 # Always remember the old PON state.
210 if self.oldpon != pon:
213 # Warn if PON goes low.
214 if self.oldpon == 1 and pon == 0:
215 self.pon_ss = self.samplenum
216 self.put(self.samplenum, self.samplenum, self.out_ann,
217 [1, ['Warning: PON goes low, DCF77 reception '
218 'no longer possible']])
219 elif self.oldpon == 0 and pon == 1:
220 self.put(self.samplenum, self.samplenum, self.out_ann,
221 [0, ['PON goes high, DCF77 reception now possible']])
222 self.put(self.pon_ss, self.samplenum, self.out_ann,
223 [1, ['Warning: PON low, DCF77 reception disabled']])
225 # Ignore samples where PON == 0, they can't contain DCF77 signals.
229 if self.state == 'WAIT FOR RISING EDGE':
230 # Wait until the next rising edge occurs.
231 if not (self.oldval == 0 and val == 1):
235 # Save the sample number where the DCF77 bit begins.
236 self.bit_start = self.samplenum
238 # Calculate the length (in ms) between two rising edges.
239 len_edges = self.bit_start - self.bit_start_old
240 len_edges_ms = int((len_edges / self.samplerate) * 1000)
242 # The time between two rising edges is usually around 1000ms.
243 # For DCF77 bit 59, there is no rising edge at all, i.e. the
244 # time between DCF77 bit 59 and DCF77 bit 0 (of the next
245 # minute) is around 2000ms. Thus, if we see an edge with a
246 # 2000ms distance to the last one, this edge marks the
247 # beginning of a new minute (and DCF77 bit 0 of that minute).
248 if len_edges_ms in range(1600, 2400 + 1):
250 self.bit_start_old = self.bit_start
251 self.dcf77_bitnumber_is_known = 1
253 self.bit_start_old = self.bit_start
254 self.state = 'GET BIT'
256 elif self.state == 'GET BIT':
257 # Wait until the next falling edge occurs.
258 if not (self.oldval == 1 and val == 0):
262 # Save the sample number where the DCF77 bit ends.
263 self.bit_end = self.samplenum
265 # Calculate the length (in ms) of the current high period.
266 len_high = self.samplenum - self.bit_start
267 len_high_ms = int((len_high / self.samplerate) * 1000)
269 # If the high signal was 100ms long, that encodes a 0 bit.
270 # If it was 200ms long, that encodes a 1 bit.
271 if len_high_ms in range(40, 160 + 1):
273 elif len_high_ms in range(161, 260 + 1):
276 bit = -1 # TODO: Error?
278 # There's no bit 59, make sure none is decoded.
279 if bit in (0, 1) and self.bitcount in range(0, 58 + 1):
280 self.handle_dcf77_bit(bit)
283 self.state = 'WAIT FOR RISING EDGE'
286 raise Exception('Invalid state: %s' % self.state)