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##
## This file is part of the libsigrokdecode project.
##
## Copyright (C) 2015 Benjamin Larsson <benjamin@southpole.se>
##
## 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, see <http://www.gnu.org/licenses/>.
##
import sigrokdecode as srd
class SamplerateError(Exception):
pass
class Decoder(srd.Decoder):
api_version = 3
id = 'em4100'
name = 'EM4100'
longname = 'RFID EM4100'
desc = 'EM4100 100-150kHz RFID protocol.'
license = 'gplv2+'
inputs = ['logic']
outputs = ['em4100']
tags = ['Logic', 'Wireless']
channels = (
{'id': 'data', 'name': 'Data', 'desc': 'Data line'},
)
options = (
{'id': 'polarity', 'desc': 'Polarity', 'default': 'active-high',
'values': ('active-low', 'active-high')},
{'id': 'datarate' , 'desc': 'Data rate', 'default': 64,
'values': (64, 32, 16)},
# {'id': 'coding', 'desc': 'Bit coding', 'default': 'biphase',
# 'values': ('biphase', 'manchester', 'psk')},
{'id': 'coilfreq', 'desc': 'Coil frequency', 'default': 125000},
)
annotations = (
('bit', 'Bit'),
('header', 'Header'),
('version-customer', 'Version/customer'),
('data', 'Data'),
('rowparity-ok', 'Row parity OK'),
('rowparity-err', 'Row parity error'),
('colparity-ok', 'Column parity OK'),
('colparity-err', 'Column parity error'),
('stopbit', 'Stop bit'),
('tag', 'Tag'),
)
annotation_rows = (
('bits', 'Bits', (0,)),
('fields', 'Fields', (1, 2, 3, 4, 5, 6, 7, 8)),
('tags', 'Tags', (9,)),
)
def __init__(self):
self.reset()
def reset(self):
self.samplerate = None
self.oldpin = None
self.last_samplenum = None
self.lastlast_samplenum = None
self.last_edge = 0
self.bit_width = 0
self.halfbit_limit = 0
self.oldpp = 0
self.oldpl = 0
self.oldsamplenum = 0
self.last_bit_pos = 0
self.ss_first = 0
self.first_one = 0
self.state = 'HEADER'
self.data = 0
self.data_bits = 0
self.ss_data = 0
self.data_parity = 0
self.payload_cnt = 0
self.data_col_parity = [0, 0, 0, 0, 0, 0]
self.col_parity = [0, 0, 0, 0, 0, 0]
self.tag = 0
self.all_row_parity_ok = True
self.col_parity_pos = []
def metadata(self, key, value):
if key == srd.SRD_CONF_SAMPLERATE:
self.samplerate = value
self.bit_width = (self.samplerate / self.options['coilfreq']) * self.options['datarate']
self.halfbit_limit = self.bit_width/2 + self.bit_width/4
self.polarity = 0 if self.options['polarity'] == 'active-low' else 1
def start(self):
self.out_ann = self.register(srd.OUTPUT_ANN)
def putbit(self, bit, ss, es):
self.put(ss, es, self.out_ann, [0, [str(bit)]])
if self.state == 'HEADER':
if bit == 1:
if self.first_one > 0:
self.first_one += 1
if self.first_one == 9:
self.put(self.ss_first, es, self.out_ann,
[1, ['Header', 'Head', 'He', 'H']])
self.first_one = 0
self.state = 'PAYLOAD'
return
if self.first_one == 0:
self.first_one = 1
self.ss_first = ss
if bit == 0:
self.first_one = 0
return
if self.state == 'PAYLOAD':
self.payload_cnt += 1
if self.data_bits == 0:
self.ss_data = ss
self.data = 0
self.data_parity = 0
self.data_bits += 1
if self.data_bits == 5:
s = 'Version/customer' if self.payload_cnt <= 10 else 'Data'
c = 2 if self.payload_cnt <= 10 else 3
self.put(self.ss_data, ss, self.out_ann,
[c, [s + ': %X' % self.data, '%X' % self.data]])
s = 'OK' if self.data_parity == bit else 'ERROR'
c = 4 if s == 'OK' else 5
if s == 'ERROR':
self.all_row_parity_ok = False
self.put(ss, es, self.out_ann,
[c, ['Row parity: ' + s, 'RP: ' + s, 'RP', 'R']])
self.tag = (self.tag << 4) | self.data
self.data_bits = 0
if self.payload_cnt == 50:
self.state = 'TRAILER'
self.payload_cnt = 0
self.data_parity ^= bit
self.data_col_parity[self.data_bits] ^= bit
self.data = (self.data << 1) | bit
return
if self.state == 'TRAILER':
self.payload_cnt += 1
if self.data_bits == 0:
self.ss_data = ss
self.data = 0
self.data_parity = 0
self.data_bits += 1
self.col_parity[self.data_bits] = bit
self.col_parity_pos.append([ss, es])
if self.data_bits == 5:
self.put(ss, es, self.out_ann, [8, ['Stop bit', 'SB', 'S']])
for i in range(1, 5):
s = 'OK' if self.data_col_parity[i] == \
self.col_parity[i] else 'ERROR'
c = 6 if s == 'OK' else 7
self.put(self.col_parity_pos[i - 1][0],
self.col_parity_pos[i - 1][1], self.out_ann,
[c, ['Column parity %d: %s' % (i, s),
'CP%d: %s' % (i, s), 'CP%d' % i, 'C']])
# Emit an annotation for valid-looking tags.
all_col_parity_ok = (self.data_col_parity[1:5] == self.col_parity[1:5])
if all_col_parity_ok and self.all_row_parity_ok:
self.put(self.ss_first, es, self.out_ann,
[9, ['Tag: %010X' % self.tag, 'Tag', 'T']])
self.tag = 0
self.data_bits = 0
if self.payload_cnt == 5:
self.state = 'HEADER'
self.payload_cnt = 0
self.data_col_parity = [0, 0, 0, 0, 0, 0]
self.col_parity = [0, 0, 0, 0, 0, 0]
self.col_parity_pos = []
self.all_row_parity_ok = True
def manchester_decode(self, pl, pp, pin):
bit = self.oldpin ^ self.polarity
if pl > self.halfbit_limit:
es = int(self.samplenum - pl/2)
if self.oldpl > self.halfbit_limit:
ss = int(self.oldsamplenum - self.oldpl/2)
else:
ss = int(self.oldsamplenum - self.oldpl)
self.putbit(bit, ss, es)
self.last_bit_pos = int(self.samplenum - pl/2)
else:
es = int(self.samplenum)
if self.oldpl > self.halfbit_limit:
ss = int(self.oldsamplenum - self.oldpl/2)
self.putbit(bit, ss, es)
self.last_bit_pos = int(self.samplenum)
else:
if self.last_bit_pos <= self.oldsamplenum - self.oldpl:
ss = int(self.oldsamplenum - self.oldpl)
self.putbit(bit, ss, es)
self.last_bit_pos = int(self.samplenum)
def decode(self):
if not self.samplerate:
raise SamplerateError('Cannot decode without samplerate.')
# Initialize internal state from the very first sample.
(pin,) = self.wait()
self.oldpin = pin
self.last_samplenum = self.samplenum
self.lastlast_samplenum = self.samplenum
self.last_edge = self.samplenum
self.oldpl = 0
self.oldpp = 0
self.oldsamplenum = 0
self.last_bit_pos = 0
while True:
# Ignore identical samples, only process edges.
(pin,) = self.wait({0: 'e'})
pl = self.samplenum - self.oldsamplenum
pp = pin
self.manchester_decode(pl, pp, pin)
self.oldpl = pl
self.oldpp = pp
self.oldsamplenum = self.samplenum
self.oldpin = pin
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