## ## This file is part of the sigrok project. ## ## Copyright (C) 2011 Gareth McMullin ## ## 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 = { # (, ): (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