diff options
Diffstat (limited to 'decoders/sae_j1850_vpw')
| -rw-r--r-- | decoders/sae_j1850_vpw/__init__.py | 24 | ||||
| -rw-r--r-- | decoders/sae_j1850_vpw/pd.py | 177 |
2 files changed, 201 insertions, 0 deletions
diff --git a/decoders/sae_j1850_vpw/__init__.py b/decoders/sae_j1850_vpw/__init__.py new file mode 100644 index 0000000..6894bfd --- /dev/null +++ b/decoders/sae_j1850_vpw/__init__.py @@ -0,0 +1,24 @@ +## +## This file is part of the libsigrokdecode project. +## +## Copyright (C) 2016 Anthony Symons <antus@pcmhacking.net> +## +## 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/>. +## + +''' +SAE J1850 Variable Pulse Width decoder. Decode GM VPW 1X and 4X Vehicle Bus. +''' + +from .pd import Decoder diff --git a/decoders/sae_j1850_vpw/pd.py b/decoders/sae_j1850_vpw/pd.py new file mode 100644 index 0000000..8faba64 --- /dev/null +++ b/decoders/sae_j1850_vpw/pd.py @@ -0,0 +1,177 @@ +## +## This file is part of the libsigrokdecode project. +## +## Copyright (C) 2016 Anthony Symons <antus@pcmhacking.net> +## +## 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 + +def timeuf(t): + return int (t * 1000.0 * 1000.0) + +def normalize_time(t): + if t >= 1.0: + return '%d s' % t + elif t >= 0.001: + return '%d ms' % (t * 1000.0) + elif t >= 0.000001: + return '%d μs' % (t * 1000.0 * 1000.0) + elif t >= 0.000000001: + return '%d ns' % (t * 1000.0 * 1000.0 * 1000.0) + else: + return '%f' % t + +class Decoder(srd.Decoder): + api_version = 3 + id = 'sae_j1850_vpw' + name = 'SAE J1850 VPW' + longname = 'SAE J1850 VPW.' + desc = 'SAE J1850 Variable Pulse Width 1x and 4x.' + license = 'gplv2+' + inputs = ['logic'] + outputs = [] + tags = ['Automotive'] + channels = ( + {'id': 'data', 'name': 'Data', 'desc': 'Data line'}, + ) + annotations = ( + ('time', 'Time'), + ('raw', 'Raw'), + ('sof', 'SOF'), + ('ifs', 'EOF/IFS'), + ('data', 'Data'), + ('packet', 'Packet'), + ) + annotation_rows = ( + ('packets', 'Packets', (5,)), + ('bytes', 'Bytes', (4,)), + ('raws', 'Raws', (1,2,3,)), + ('times', 'Times', (0,)), + ) + + def __init__(self): + self.reset() + + def reset(self): + self.state = 'IDLE' + self.samplerate = None + self.byte = 0 # the byte offset in the packet + self.mode = 0 # for by packet decode + self.data = 0 # the current byte + self.datastart = 0 # sample number this byte started at + self.csa = 0 # track the last byte seperately to retrospectively add the CS marker + self.csb = 0 + self.count = 0 # which bit number we are up to + self.active = 0 # which logic level is considered active + + # vpw timings. ideal, min and max tollerances. + # From SAE J1850 1995 rev section 23.406 + + self.sof = 200 + self.sofl = 164 + self.sofh = 245 # 240 by the spec, 245 so a 60us 4x sample will pass + self.long = 128 + self.longl = 97 + self.longh = 170 # 164 by the spec but 170 for low sample rate tolerance. + self.short = 64 + self.shortl = 24 # 35 by the spec, 24 to allow down to 6us as measured in practice for 4x @ 1mhz sampling + self.shorth = 97 + self.ifs = 240 + self.spd = 1 # set to 4 when a 4x SOF is detected (VPW high speed frame) + + def handle_bit(self, ss, es, b): + self.data |= (b << 7-self.count) # MSB-first + self.put(ss, es, self.out_ann, [1, ["%d" % b]]) + if self.count == 0: + self.datastart = ss + if self.count == 7: + self.csa = self.datastart # for CS + self.csb = self.samplenum # for CS + self.put(self.datastart, self.samplenum, self.out_ann, [4, ["%02X" % self.data]]) + # add protocol parsing here + if self.byte == 0: + self.put(self.datastart, self.samplenum, self.out_ann, [5, ['Priority','Prio','P']]) + elif self.byte == 1: + self.put(self.datastart, self.samplenum, self.out_ann, [5, ['Destination','Dest','D']]) + elif self.byte == 2: + self.put(self.datastart, self.samplenum, self.out_ann, [5, ['Source','Src','S']]) + elif self.byte == 3: + self.put(self.datastart, self.samplenum, self.out_ann, [5, ['Mode','M']]) + self.mode = self.data + elif self.mode == 1 and self.byte == 4: # mode 1 payload + self.put(self.datastart, self.samplenum, self.out_ann, [5, ['Pid','P']]) + + # prepare for next byte + self.count = -1 + self.data = 0 + self.byte = self.byte + 1 # track packet offset + self.count = self.count + 1 + + def metadata(self, key, value): + if key == srd.SRD_CONF_SAMPLERATE: + self.samplerate = value + + def start(self): + self.out_ann = self.register(srd.OUTPUT_ANN) + + def decode(self): + if not self.samplerate: + raise SamplerateError('Cannot decode without samplerate.') + + self.wait({0: 'e'}) + es = self.samplenum + while True: + ss = es + pin, = self.wait({0: 'e'}) + es = self.samplenum + + samples = es - ss + txt = normalize_time(samples / self.samplerate) + self.put(ss, es, self.out_ann, [0, [txt]]) + t = timeuf(samples / self.samplerate) + if self.state == 'IDLE': # detect and set speed from the size of sof + if pin == self.active and t in range(self.sofl , self.sofh): + self.put(ss, es, self.out_ann, [1, ['1X SOF', 'S1', 'S']]) + self.spd = 1 + self.data = 0 + self.count = 0 + self.state = 'DATA' + elif pin == self.active and t in range(int(self.sofl / 4) , int(self.sofh / 4)): + self.put(ss, es, self.out_ann, [1, ['4X SOF', 'S4', '4']]) + self.spd = 4 + self.data = 0 + self.count = 0 + self.state = 'DATA' + + elif self.state == 'DATA': + if t >= int(self.ifs / self.spd): + self.state = 'IDLE' + self.put(ss, es, self.out_ann, [1, ["EOF/IFS", "E"]]) # EOF=239-280 IFS=281+ + self.put(self.csa, self.csb, self.out_ann, [5, ['Checksum','CS','C']]) # retrospective print of CS + self.byte = 0 # reset packet offset + elif t in range(int(self.shortl / self.spd), int(self.shorth / self.spd)): + if pin == self.active: + self.handle_bit(ss, es, 1) + else: + self.handle_bit(ss, es, 0) + elif t in range(int(self.longl / self.spd), int(self.longh / self.spd)): + if pin == self.active: + self.handle_bit(ss, es, 0) + else: + self.handle_bit(ss, es, 1) |