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Diffstat (limited to 'decoders/usb_protocol/usb_protocol.py')
| -rw-r--r-- | decoders/usb_protocol/usb_protocol.py | 137 |
1 files changed, 137 insertions, 0 deletions
diff --git a/decoders/usb_protocol/usb_protocol.py b/decoders/usb_protocol/usb_protocol.py new file mode 100644 index 0000000..b1cd33b --- /dev/null +++ b/decoders/usb_protocol/usb_protocol.py @@ -0,0 +1,137 @@ +## +## 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 (low-speed and full-speed) protocol decoder + +import sigrokdecode as srd + +# 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 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: %s' % sync + + return pid + ' ' + data + +class Decoder(srd.Decoder): + api_version = 1 + id = 'usb_protocol' + name = 'USB protocol' + longname = 'Universal Serial Bus (LS/FS) protocol' + desc = 'USB 1.x (low-speed and full-speed) serial protocol.' + license = 'gplv2+' + inputs = ['usb_signalling'] + outputs = ['usb_protocol'] + probes = [] + 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 = '' + self.state = 'IDLE' + + def start(self, metadata): + self.samplerate = metadata['samplerate'] + self.out_proto = self.add(srd.OUTPUT_PROTO, 'usb_protocol') + self.out_ann = self.add(srd.OUTPUT_ANN, 'usb_protocol') + + def report(self): + pass + + def decode(self, ss, es, data): + (ptype, pdata) = data + + if ptype == 'PACKET': + self.put(0, 0, self.out_ann, [0, [packet_decode(pdata)]]) + + # TODO. + |