-##
-## This file is part of the sigrok project.
-##
-## Copyright (C) 2011 Gareth McMullin <gareth@blacksphere.co.nz>
-##
-## 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 (low-speed and full-speed) protocol decoder
-
-import sigrokdecode as srd
-
-# 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!
-syms = {
- # (<dp>, <dm>): <symbol/state>
- (0, 0): 'SE0',
- (1, 0): 'J',
- (0, 1): 'K',
- (1, 1): 'SE1',
-}
-
-# Packet IDs (PIDs).
-# The first 4 bits are the 'packet type' field, the last 4 bits are the
-# 'check field' (each bit in the check field must be the inverse of the resp.
-# bit in the 'packet type' field; if not, that's a 'PID error').
-# For the 4-bit strings, the left-most '1' or '0' is the LSB, i.e. it's sent
-# to the bus first.
-pids = {
- # Tokens
- '10000111': ['OUT', 'Address & EP number in host-to-function transaction'],
- '10010110': ['IN', 'Address & EP number in function-to-host transaction'],
- '10100101': ['SOF', 'Start-Of-Frame marker & frame number'],
- '10110100': ['SETUP', 'Address & EP number in host-to-function transaction for SETUP to a control pipe'],
-
- # Data
- # Note: DATA2 and MDATA are HS-only.
- '11000011': ['DATA0', 'Data packet PID even'],
- '11010010': ['DATA1', 'Data packet PID odd'],
- '11100001': ['DATA2', 'Data packet PID HS, high bandwidth isosynchronous transaction in a microframe'],
- '11110000': ['MDATA', 'Data packet PID HS for split and high-bandwidth isosynchronous transactions'],
-
- # Handshake
- '01001011': ['ACK', 'Receiver accepts error-free packet'],
- '01011010': ['NAK', 'Receiver cannot accept or transmitter cannot send'],
- '01111000': ['STALL', 'EP halted or control pipe request unsupported'],
- '01101001': ['NYET', 'No response yet from receiver'],
-
- # Special
- '00111100': ['PRE', 'Host-issued preamble; enables downstream bus traffic to low-speed devices'],
- '00111100': ['ERR', 'Split transaction error handshake'],
- '00011110': ['SPLIT', 'HS split transaction token'],
- '00101101': ['PING', 'HS flow control probe for a bulk/control EP'],
- '00001111': ['Reserved', 'Reserved PID'],
-}
-
-def get_sym(signalling, dp, dm):
- # Note: Low-speed J and K are inverted compared to the full-speed J and K!
- if signalling == 'low-speed':
- s = syms[dp, dm]
- if s == 'J':
- return 'K'
- elif s == 'K':
- return 'J'
- else:
- return s
- elif signalling == 'full-speed':
- return syms[dp, dm]
-
-def bitstr_to_num(bitstr):
- if not bitstr:
- return 0
- l = list(bitstr)
- l.reverse()
- return int(''.join(l), 2)
-
-def packet_decode(packet):
- sync = packet[:8]
- pid = packet[8:16]
- pid = pids.get(pid, (pid, ''))[0]
-
- # Remove CRC.
- if pid in ('OUT', 'IN', 'SOF', 'SETUP'):
- data = packet[16:-5]
- if pid == 'SOF':
- data = str(bitstr_to_num(data))
- else:
- dev = bitstr_to_num(data[:7])
- ep = bitstr_to_num(data[7:])
- data = 'DEV %d EP %d' % (dev, ep)
- elif pid in ('DATA0', 'DATA1'):
- data = packet[16:-16]
- tmp = ''
- while data:
- tmp += '%02x ' % bitstr_to_num(data[:8])
- data = data[8:]
- data = tmp
- else:
- data = packet[16:]
-
- # The SYNC pattern for low-speed/full-speed is KJKJKJKK (0001).
- if sync != '00000001':
- return 'SYNC INVALID!'
-
- return pid + ' ' + data
-
-class Decoder(srd.Decoder):
- api_version = 1
- id = 'usb'
- name = 'USB'
- longname = 'Universal Serial Bus (LS/FS)'
- desc = 'USB 1.x (low-speed and full-speed) serial protocol.'
- license = 'gplv2+'
- inputs = ['logic']
- outputs = ['usb']
- 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'
- self.samplenum = 0
- self.scount = 0
- self.packet = ''
-
- def start(self, metadata):
- self.samplerate = metadata['samplerate']
-
- # self.out_proto = self.add(srd.OUTPUT_PROTO, 'usb')
- self.out_ann = self.add(srd.OUTPUT_ANN, 'usb')
-
- 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
-
- sym = get_sym(self.options['signalling'], dp, dm)
-
- # Wait for a symbol change (i.e., change in D+/D- lines).
- if sym == self.sym:
- continue
-
- # if self.scount == 1:
- # # We ignore single sample width "pulses", i.e., symbol changes
- # # (D+/D- line changes). I sometimes get these with the OLS.
- # self.sym = sym
- # self.scount = 0
- # 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]])
- else:
- # Longer than EOP, assume reset.
- self.put(0, 0, self.out_ann, [0, ['RESET']])
- 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.scount = 0
- self.sym = sym
-
projects / libsigrokdecode.git / commitdiff