diff options
Diffstat (limited to 'decoders/flexray')
| -rw-r--r-- | decoders/flexray/__init__.py | 32 | ||||
| -rw-r--r-- | decoders/flexray/pd.py | 413 |
2 files changed, 445 insertions, 0 deletions
diff --git a/decoders/flexray/__init__.py b/decoders/flexray/__init__.py new file mode 100644 index 0000000..73dc7fa --- /dev/null +++ b/decoders/flexray/__init__.py @@ -0,0 +1,32 @@ +## +## This file is part of the libsigrokdecode project. +## +## Copyright (C) 2019 Stephan Thiele <stephan.thiele@mailbox.org> +## +## 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/>. +## + +''' +FlexRay is a fast, deterministic and fault-tolerant fieldbus system +which is used in cars in high security related areas like X-by-Wire. + +It is the result of the FlexRay consortium which consisted of BMW, +Daimler, Motorola (today Freescale) and Philips, with the goal of +working out a common standard automotive bus system. + +This decoder assumes that at least one channel of a logic level RX line +of a transceiver is sampled (e.g. NXP TJA1080). +''' + +from .pd import Decoder diff --git a/decoders/flexray/pd.py b/decoders/flexray/pd.py new file mode 100644 index 0000000..0c52041 --- /dev/null +++ b/decoders/flexray/pd.py @@ -0,0 +1,413 @@ +## +## This file is part of the libsigrokdecode project. +## +## Copyright (C) 2019 Stephan Thiele <stephan.thiele@mailbox.org> +## +## 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 + +# Selection of constants as defined in FlexRay specification 3.0.1 Chapter A.1: +class Const: + cChannelIdleDelimiter = 11 + cCrcInitA = 0xFEDCBA + cCrcInitB = 0xABCDEF + cCrcPolynomial = 0x5D6DCB + cCrcSize = 24 + cCycleCountMax = 63 + cdBSS = 2 + cdCAS = 30 + cdFES = 2 + cdFSS = 1 + cHCrcInit = 0x01A + cHCrcPolynomial = 0x385 + cHCrcSize = 11 + cSamplesPerBit = 8 + cSlotIDMax = 2047 + cStaticSlotIDMax = 1023 + cVotingSamples = 5 + +class SamplerateError(Exception): + pass + +class Decoder(srd.Decoder): + api_version = 3 + id = 'flexray' + name = 'FlexRay' + longname = 'FlexRay' + desc = 'Automotive network communications protocol.' + license = 'gplv2+' + inputs = ['logic'] + outputs = [] + tags = ['Automotive'] + channels = ( + {'id': 'channel', 'name': 'Channel', 'desc': 'FlexRay bus channel'}, + ) + options = ( + {'id': 'channel_type', 'desc': 'Channel type', 'default': 'A', + 'values': ('A', 'B')}, + {'id': 'bitrate', 'desc': 'Bitrate (Mbit/s)', 'default': '10.0', + 'values': ('10.0', '5.0', '2.5')}, + ) + annotations = ( + ('data', 'FlexRay payload data'), + ('tss', 'Transmission start sequence'), + ('fss', 'Frame start sequence'), + ('reserved-bit', 'Reserved bit'), + ('ppi', 'Payload preamble indicator'), + ('null-frame', 'Nullframe indicator'), + ('sync-frame', 'Full identifier'), + ('startup-frame', 'Startup frame indicator'), + ('id', 'Frame ID'), + ('length', 'Data length'), + ('header-crc', 'Header CRC'), + ('cycle', 'Cycle code'), + ('data-byte', 'Data byte'), + ('frame-crc', 'Frame CRC'), + ('cid-delimiter', 'Channel idle delimiter'), + ('bss', 'Byte start sequence'), + ('warnings', 'Human-readable warnings'), + ('bit', 'Bit'), + ('cid', 'Channel idle delimiter'), + ('dts', 'Dynamic trailing sequence'), + ('cas', 'Collision avoidance symbol'), + ) + annotation_rows = ( + ('bits', 'Bits', (15, 17)), + ('fields', 'Fields', tuple(range(15)) + (18, 19, 20)), + ('warnings', 'Warnings', (16,)), + ) + + def __init__(self): + self.reset() + + def reset(self): + self.samplerate = None + self.reset_variables() + + def start(self): + self.out_ann = self.register(srd.OUTPUT_ANN) + + def metadata(self, key, value): + if key == srd.SRD_CONF_SAMPLERATE: + bitrate = 1000000 * float(self.options['bitrate']) + self.samplerate = value + self.bit_width = float(self.samplerate) / bitrate + self.sample_point = (self.bit_width / 100.0) * self.sample_point_percent + + # Generic helper for FlexRay bit annotations. + def putg(self, ss, es, data): + left, right = int(self.sample_point), int(self.bit_width - self.sample_point) + self.put(ss - left, es + right, self.out_ann, data) + + # Single-FlexRay-bit annotation using the current samplenum. + def putx(self, data): + self.putg(self.samplenum, self.samplenum, data) + + # Multi-FlexRay-bit annotation from self.ss_block to current samplenum. + def putb(self, data): + self.putg(self.ss_block, self.samplenum, data) + + # Generic CRC algorithm for any bit size and any data length. Used for + # 11-bit header and 24-bit trailer. Not very efficient but at least it + # works for now. + # + # TODO: + # - use precalculated tables to increase performance. + # - Add support for reverse CRC calculations. + + @staticmethod + def crc(data, data_len_bits, polynom, crc_len_bits, iv=0, xor=0): + reg = iv ^ xor + + for i in range(data_len_bits - 1, -1, -1): + bit = ((reg >> (crc_len_bits - 1)) & 0x1) ^ ((data >> i) & 0x1) + reg <<= 1 + if bit: + reg ^= polynom + + mask = (1 << crc_len_bits) - 1 + crc = reg & mask + + return crc ^ xor + + def reset_variables(self): + self.sample_point_percent = 50 # TODO: use vote based sampling + self.state = 'IDLE' + self.tss_start = self.tss_end = self.frame_type = self.dlc = None + self.rawbits = [] # All bits, including byte start sequence bits + self.bits = [] # Only actual FlexRay frame bits (no byte start sequence bits) + self.curbit = 0 # Current bit of FlexRay frame (bit 0 == FSS) + self.last_databit = 999 # Positive value that bitnum+x will never match + self.last_xmit_bit = 999 # Positive value that bitnum+x will never match + self.ss_block = None + self.ss_databytebits = [] + self.end_of_frame = False + self.dynamic_frame = False + self.ss_bit0 = None + self.ss_bit1 = None + self.ss_bit2 = None + + # Poor man's clock synchronization. Use signal edges which change to + # dominant state in rather simple ways. This naive approach is neither + # aware of the SYNC phase's width nor the specific location of the edge, + # but improves the decoder's reliability when the input signal's bitrate + # does not exactly match the nominal rate. + def dom_edge_seen(self, force=False): + self.dom_edge_snum = self.samplenum + self.dom_edge_bcount = self.curbit + + # Determine the position of the next desired bit's sample point. + def get_sample_point(self, bitnum): + samplenum = self.dom_edge_snum + samplenum += self.bit_width * (bitnum - self.dom_edge_bcount) + samplenum += self.sample_point + return int(samplenum) + + def is_bss_sequence(self): + # FlexRay uses NRZ encoding and adds a binary 10 sequence before each + # byte. After each 8 data bits, a BSS sequence is added but not after + # frame CRC. + + if self.end_of_frame: + return False + + if (len(self.rawbits) - 2) % 10 == 0: + return True + elif (len(self.rawbits) - 3) % 10 == 0: + return True + + return False + + def handle_bit(self, fr_rx): + self.rawbits.append(fr_rx) + self.bits.append(fr_rx) + + # Get the index of the current FlexRay frame bit. + bitnum = len(self.bits) - 1 + + # If this is a byte start sequence remove it from self.bits and ignore it. + if self.is_bss_sequence(): + self.bits.pop() + + if bitnum > 1: + self.putx([15, [str(fr_rx)]]) + else: + if len(self.rawbits) == 2: + self.ss_bit1 = self.samplenum + elif len(self.rawbits) == 3: + self.ss_bit2 = self.samplenum + + self.curbit += 1 # Increase self.curbit (bitnum is not affected). + return + else: + if bitnum > 1: + self.putx([17, [str(fr_rx)]]) + + # Bit 0: Frame start sequence (FSS) bit + if bitnum == 0: + self.ss_bit0 = self.samplenum + + # Bit 1: Start of header + elif bitnum == 1: + if self.rawbits[:3] == [1, 1, 0]: + self.put(self.tss_start, self.tss_end, self.out_ann, + [1, ['Transmission start sequence', 'TSS']]) + + self.putg(self.ss_bit0, self.ss_bit0, [17, [str(self.rawbits[:3][0])]]) + self.putg(self.ss_bit0, self.ss_bit0, [2, ['FSS', 'Frame start sequence']]) + self.putg(self.ss_bit1, self.ss_bit1, [15, [str(self.rawbits[:3][1])]]) + self.putg(self.ss_bit2, self.ss_bit2, [15, [str(self.rawbits[:3][2])]]) + self.putx([17, [str(fr_rx)]]) + self.putx([3, ['Reserved bit: %d' % fr_rx, 'RB: %d' % fr_rx, 'RB']]) + else: + self.put(self.tss_start, self.tss_end, self.out_ann, + [20, ['Collision avoidance symbol', 'CAS']]) + self.reset_variables() + + # TODO: warning, if sequence is neither [1, 1, 0] nor [1, 1, 1] + + # Bit 2: Payload preamble indicator. Must be 0 if null frame indicator is 0. + elif bitnum == 2: + self.putx([4, ['Payload preamble indicator: %d' % fr_rx, + 'PPI: %d' % fr_rx]]) + + # Bit 3: Null frame indicator (inversed) + elif bitnum == 3: + data_type = 'data frame' if fr_rx else 'null frame' + self.putx([5, ['Null frame indicator: %s' % data_type, + 'NF: %d' % fr_rx, 'NF']]) + + # Bit 4: Sync frame indicator + # Must be 1 if startup frame indicator is 1. + elif bitnum == 4: + self.putx([6, ['Sync frame indicator: %d' % fr_rx, + 'Sync: %d' % fr_rx, 'Sync']]) + + # Bit 5: Startup frame indicator + elif bitnum == 5: + self.putx([7, ['Startup frame indicator: %d' % fr_rx, + 'Startup: %d' % fr_rx, 'Startup']]) + + # Remember start of ID (see below). + elif bitnum == 6: + self.ss_block = self.samplenum + + # Bits 6-16: Frame identifier (ID[10..0]) + # ID must NOT be 0. + elif bitnum == 16: + self.id = int(''.join(str(d) for d in self.bits[6:]), 2) + self.putb([8, ['Frame ID: %d' % self.id, 'ID: %d' % self.id, + '%d' % self.id]]) + + # Remember start of payload length (see below). + elif bitnum == 17: + self.ss_block = self.samplenum + + # Bits 17-23: Payload length (Length[7..0]) + # Payload length in header is the half of the real payload size. + elif bitnum == 23: + self.payload_length = int(''.join(str(d) for d in self.bits[17:]), 2) + self.putb([9, ['Payload length: %d' % self.payload_length, + 'Length: %d' % self.payload_length, + '%d' % self.payload_length]]) + + # Remember start of header CRC (see below). + elif bitnum == 24: + self.ss_block = self.samplenum + + # Bits 24-34: Header CRC (11-bit) (HCRC[11..0]) + # Calculation of header CRC is equal on both channels. + elif bitnum == 34: + bits = ''.join([str(b) for b in self.bits[4:24]]) + header_to_check = int(bits, 2) + expected_crc = self.crc(header_to_check, len(bits), + Const.cHCrcPolynomial, Const.cHCrcSize, Const.cHCrcInit) + self.header_crc = int(''.join(str(d) for d in self.bits[24:]), 2) + + crc_ok = self.header_crc == expected_crc + crc_ann = "OK" if crc_ok else "bad" + + self.putb([10, ['Header CRC: 0x%X (%s)' % (self.header_crc, crc_ann), + '0x%X (%s)' % (self.header_crc, crc_ann), + '0x%X' % self.header_crc]]) + + # Remember start of cycle code (see below). + elif bitnum == 35: + self.ss_block = self.samplenum + + # Bits 35-40: Cycle code (Cyc[6..0]) + # Cycle code. Must be between 0 and 63. + elif bitnum == 40: + self.cycle = int(''.join(str(d) for d in self.bits[35:]), 2) + self.putb([11, ['Cycle: %d' % self.cycle, 'Cyc: %d' % self.cycle, + '%d' % self.cycle]]) + self.last_databit = 41 + 2 * self.payload_length * 8 + + # Remember all databyte bits, except the very last one. + elif bitnum in range(41, self.last_databit): + self.ss_databytebits.append(self.samplenum) + + # Bits 41-X: Data field (0-254 bytes, depending on length) + # The bits within a data byte are transferred MSB-first. + elif bitnum == self.last_databit: + self.ss_databytebits.append(self.samplenum) # Last databyte bit. + for i in range(2 * self.payload_length): + x = 40 + (8 * i) + 1 + b = int(''.join(str(d) for d in self.bits[x:x + 8]), 2) + ss = self.ss_databytebits[i * 8] + es = self.ss_databytebits[((i + 1) * 8) - 1] + self.putg(ss, es, [12, ['Data byte %d: 0x%02x' % (i, b), + 'DB%d: 0x%02x' % (i, b), '%02X' % b]]) + self.ss_databytebits = [] + self.ss_block = self.samplenum # Remember start of trailer CRC. + + # Trailer CRC (24-bit) (CRC[11..0]) + # Initialization vector of channel A and B are different, so CRCs are + # different for same data. + elif bitnum == self.last_databit + 23: + bits = ''.join([str(b) for b in self.bits[1:-24]]) + frame_to_check = int(bits, 2) + iv = Const.cCrcInitA if self.options['channel_type'] == 'A' else Const.cCrcInitB + expected_crc = self.crc(frame_to_check, len(bits), + Const.cCrcPolynomial, Const.cCrcSize, iv=iv) + self.frame_crc = int(''.join(str(d) for d in self.bits[self.last_databit:]), 2) + + crc_ok = self.frame_crc == expected_crc + crc_ann = "OK" if crc_ok else "bad" + + self.putb([13, ['Frame CRC: 0x%X (%s)' % (self.frame_crc, crc_ann), + '0x%X (%s)' % (self.frame_crc, crc_ann), + '0x%X' % self.frame_crc]]) + self.end_of_frame = True + + # Remember start of frame end sequence (see below). + elif bitnum == self.last_databit + 24: + self.ss_block = self.samplenum + + # Frame end sequence, must be 1 followed by 0. + elif bitnum == self.last_databit + 25: + self.putb([14, ['Frame end sequence', 'FES']]) + + # Check for DTS + elif bitnum == self.last_databit + 26: + if not fr_rx: + self.dynamic_frame = True + else: + self.last_xmit_bit = bitnum + self.ss_block = self.samplenum + + # Remember start of channel idle delimiter (see below). + elif bitnum == self.last_xmit_bit: + self.ss_block = self.samplenum + + # Channel idle limiter (CID[11..0]) + elif bitnum == self.last_xmit_bit + Const.cChannelIdleDelimiter - 1: + self.putb([18, ['Channel idle delimiter', 'CID']]) + self.reset_variables() + + # DTS if dynamic frame + elif bitnum > self.last_databit + 27: + if self.dynamic_frame: + if fr_rx: + if self.last_xmit_bit == 999: + self.putb([19, ['Dynamic trailing sequence', 'DTS']]) + self.last_xmit_bit = bitnum + 1 + self.ss_block = self.samplenum + + self.curbit += 1 + + def decode(self): + if not self.samplerate: + raise SamplerateError('Cannot decode without samplerate.') + + while True: + # State machine. + if self.state == 'IDLE': + # Wait for a dominant state (logic 0) on the bus. + (fr_rx,) = self.wait({0: 'l'}) + self.tss_start = self.samplenum + (fr_rx,) = self.wait({0: 'h'}) + self.tss_end = self.samplenum + self.dom_edge_seen(force = True) + self.state = 'GET BITS' + elif self.state == 'GET BITS': + # Wait until we're in the correct bit/sampling position. + pos = self.get_sample_point(self.curbit) + (fr_rx,) = self.wait([{'skip': pos - self.samplenum}, {0: 'f'}]) + if self.matched[1]: + self.dom_edge_seen() + if self.matched[0]: + self.handle_bit(fr_rx) |