+##
+## This file is part of the sigrok project.
+##
+## Copyright (C) 2011 Gareth McMullin <gareth@blacksphere.co.nz>
+## Copyright (C) 2012 Uwe Hermann <uwe@hermann-uwe.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
+##
+
+# USB signalling (low-speed and full-speed) protocol decoder
+
+import sigrokdecode as srd
+
+# Low-/full-speed symbols (used as states of our state machine, too).
+# Note: Low-speed J and K are inverted compared to the full-speed J and K!
+symbols_ls = {
+ # (<dp>, <dm>): <symbol/state>
+ (0, 0): 'SE0',
+ (1, 0): 'K',
+ (0, 1): 'J',
+ (1, 1): 'SE1',
+}
+symbols_fs = {
+ # (<dp>, <dm>): <symbol/state>
+ (0, 0): 'SE0',
+ (1, 0): 'J',
+ (0, 1): 'K',
+ (1, 1): 'SE1',
+}
+
+class Decoder(srd.Decoder):
+ api_version = 1
+ id = 'usb_signalling'
+ name = 'USB signalling'
+ longname = 'Universal Serial Bus (LS/FS) signalling'
+ desc = 'USB 1.x (low-speed and full-speed) signalling protocol.'
+ license = 'gplv2+'
+ inputs = ['logic']
+ outputs = ['usb_signalling']
+ probes = [
+ {'id': 'dp', 'name': 'D+', 'desc': 'USB D+ signal'},
+ {'id': 'dm', 'name': 'D-', 'desc': 'USB D- signal'},
+ ]
+ optional_probes = []
+ options = {
+ 'signalling': ['Signalling', 'full-speed'],
+ }
+ annotations = [
+ ['Text', 'Human-readable text']
+ ]
+
+ def __init__(self):
+ self.sym = 'J' # The "idle" state is J.
+ self.samplenum = 0
+ self.scount = 0
+ self.packet = ''
+ self.syms = []
+
+ def start(self, metadata):
+ self.samplerate = metadata['samplerate']
+ self.out_proto = self.add(srd.OUTPUT_PROTO, 'usb_signalling')
+ self.out_ann = self.add(srd.OUTPUT_ANN, 'usb_signalling')
+
+ def report(self):
+ pass
+
+ def decode(self, ss, es, data):
+ for (self.samplenum, (dp, dm)) in data:
+
+ # Note: self.samplenum is the absolute sample number, whereas
+ # self.scount only counts the number of samples since the
+ # last change in the D+/D- lines.
+ self.scount += 1
+
+ if self.options['signalling'] == 'low-speed':
+ sym = symbols_ls[dp, dm]
+ elif self.options['signalling'] == 'full-speed':
+ sym = symbols_fs[dp, dm]
+
+ self.put(0, 0, self.out_ann, [0, [sym]])
+ self.put(0, 0, self.out_proto, ['SYM', sym])
+
+ # Wait for a symbol change (i.e., change in D+/D- lines).
+ if sym == self.sym:
+ continue
+
+ ## # Debug code:
+ ## self.syms.append(sym + ' ')
+ ## if len(self.syms) == 16:
+ ## self.put(0, 0, self.out_ann, [0, [''.join(self.syms)]])
+ ## self.syms = []
+ # continue
+
+ # How many bits since the last transition?
+ if self.packet != '' or self.sym != 'J':
+ if self.options['signalling'] == 'low-speed':
+ bitrate = 1500000 # 1.5Mb/s (+/- 1.5%)
+ elif self.options['signalling'] == 'full-speed':
+ bitrate = 12000000 # 12Mb/s (+/- 0.25%)
+ bitcount = int((self.scount - 1) * bitrate / self.samplerate)
+ else:
+ bitcount = 0
+
+ if self.sym == 'SE0':
+ if bitcount == 1:
+ # End-Of-Packet (EOP)
+ # self.put(0, 0, self.out_ann,
+ # [0, [packet_decode(self.packet), self.packet]])
+ if self.packet != '': # FIXME?
+ self.put(0, 0, self.out_ann, [0, ['PACKET: %s' % self.packet]])
+ self.put(0, 0, self.out_proto, ['PACKET', self.packet])
+ else:
+ # Longer than EOP, assume reset.
+ self.put(0, 0, self.out_ann, [0, ['RESET']])
+ self.put(0, 0, self.out_proto, ['RESET', None])
+ # self.put(0, 0, self.out_ann, [0, [self.packet]])
+ self.scount = 0
+ self.sym = sym
+ self.packet = ''
+ continue
+
+ # Add bits to the packet string.
+ self.packet += '1' * bitcount
+
+ # Handle bit stuffing.
+ if bitcount < 6 and sym != 'SE0':
+ self.packet += '0'
+ elif bitcount > 6:
+ self.put(0, 0, self.out_ann, [0, ['BIT STUFF ERROR']])
+ self.put(0, 0, self.out_proto, ['BIT STUFF ERROR', None])
+
+ self.scount = 0
+ self.sym = sym
+
projects / libsigrokdecode.git / commitdiff