diff options
| -rw-r--r-- | configure.ac | 1 | ||||
| -rw-r--r-- | decoders/Makefile.am | 1 | ||||
| -rw-r--r-- | decoders/can/Makefile.am | 26 | ||||
| -rw-r--r-- | decoders/can/__init__.py | 36 | ||||
| -rw-r--r-- | decoders/can/pd.py | 296 |
5 files changed, 360 insertions, 0 deletions
diff --git a/configure.ac b/configure.ac index 7dab1fe..a5335a5 100644 --- a/configure.ac +++ b/configure.ac @@ -150,6 +150,7 @@ AC_CONFIG_FILES([Makefile libsigrokdecode.pc decoders/Makefile decoders/avr_isp/Makefile + decoders/can/Makefile decoders/dcf77/Makefile decoders/edid/Makefile decoders/i2c/Makefile diff --git a/decoders/Makefile.am b/decoders/Makefile.am index 48f8922..52f999e 100644 --- a/decoders/Makefile.am +++ b/decoders/Makefile.am @@ -21,6 +21,7 @@ # Please keep this list in alphabetical order. SUBDIRS = \ avr_isp \ + can \ dcf77 \ edid \ i2c \ diff --git a/decoders/can/Makefile.am b/decoders/can/Makefile.am new file mode 100644 index 0000000..51af7c4 --- /dev/null +++ b/decoders/can/Makefile.am @@ -0,0 +1,26 @@ +## +## This file is part of the sigrok project. +## +## 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 +## + +pkgdatadir = $(DECODERS_DIR)/can + +dist_pkgdata_DATA = __init__.py pd.py + +CLEANFILES = *.pyc + diff --git a/decoders/can/__init__.py b/decoders/can/__init__.py new file mode 100644 index 0000000..55c08ba --- /dev/null +++ b/decoders/can/__init__.py @@ -0,0 +1,36 @@ +## +## This file is part of the sigrok project. +## +## 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 +## + +''' +CAN protocol decoder. + +TODO: Description. + +Details: +TODO + +Protocol output format: + +TODO. + +''' + +from .pd import * + diff --git a/decoders/can/pd.py b/decoders/can/pd.py new file mode 100644 index 0000000..5733e18 --- /dev/null +++ b/decoders/can/pd.py @@ -0,0 +1,296 @@ +## +## This file is part of the sigrok project. +## +## 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 +## + +# CAN protocol decoder + +import sigrokdecode as srd + +class Decoder(srd.Decoder): + api_version = 1 + id = 'can' + name = 'CAN' + longname = 'Controller area network' + desc = 'Field bus protocol for distributed realtime control.' + license = 'gplv2+' + inputs = ['logic'] + outputs = ['can'] + probes = [ + {'id': 'can_rx', 'name': 'CAN RX', 'desc': 'CAN bus line'}, + ] + optional_probes = [] + options = { + 'bitrate': ['Bitrate', 1000000], # 1Mbit/s + 'sample_point': ['Sample point', 70], # 70% + } + annotations = [ + ['Text', 'Human-readable text'], + ['Warnings', 'Human-readable warnings'], + ] + + def __init__(self, **kwargs): + self.reset_variables() + + def start(self, metadata): + # self.out_proto = self.add(srd.OUTPUT_PROTO, 'can') + self.out_ann = self.add(srd.OUTPUT_ANN, 'can') + + self.samplerate = metadata['samplerate'] + self.bit_width = float(self.samplerate) / float(self.options['bitrate']) + self.bitpos = (self.bit_width / 100.0) * self.options['sample_point'] + + def report(self): + pass + + def reset_variables(self): + self.state = 'IDLE' + self.sof = self.frame_type = self.dlc = None + self.rawbits = [] # All bits, including stuff bits + self.bits = [] # Only actual CAN frame bits (no stuff bits) + self.curbit = 0 # Current bit of CAN frame (bit 0 == SOF) + self.last_databit = 999 # Positive value that bitnum+x will never match + + # Return True if we reached the desired bit position, False otherwise. + def reached_bit(self, bitnum): + bitpos = int(self.sof + (self.bit_width * bitnum) + self.bitpos) + if self.samplenum >= bitpos: + return True + return False + + def is_stuff_bit(self): + # CAN uses NRZ encoding and bit stuffing. + # After 5 identical bits, a stuff bit of opposite value is added. + last_6_bits = self.rawbits[-6:] + if last_6_bits not in ([0, 0, 0, 0, 0, 1], [1, 1, 1, 1, 1, 0]): + return False + + # Stuff bit. Keep it in self.rawbits, but drop it from self.bits. + self.put(0, 0, self.out_ann, [0, ['Stuff bit: %d' % self.rawbits[-1]]]) + self.bits.pop() # Drop last bit. + return True + + def is_valid_crc(self, crc_bits): + return True # TODO + + def decode_error_frame(self, bits): + pass # TODO + + def decode_overload_frame(self, bits): + pass # TODO + + # Both standard and extended frames end with CRC, CRC delimiter, ACK, + # ACK delimiter, and EOF fields. Handle them in a common function. + # Returns True if the frame ended (EOF), False otherwise. + def decode_frame_end(self, can_rx, bitnum): + + # CRC sequence (15 bits) + if bitnum == (self.last_databit + 15): + x = self.last_databit + 1 + crc_bits = self.bits[x:x + 15 + 1] + self.crc = int(''.join(str(d) for d in crc_bits), 2) + self.put(0, 0, self.out_ann, [0, ['CRC: 0x%04x' % self.crc]]) + + if not self.is_valid_crc(crc_bits): + self.put(0, 0, self.out_ann, [0, ['CRC is invalid']]) + + # CRC delimiter bit (recessive) + elif bitnum == (self.last_databit + 16): + self.put(0, 0, self.out_ann, [0, ['CRC delimiter: %d' % can_rx]]) + + # ACK slot bit (dominant: ACK, recessive: NACK) + elif bitnum == (self.last_databit + 17): + ack = 'ACK' if can_rx == 0 else 'NACK' + self.put(0, 0, self.out_ann, [0, ['ACK slot: %s' % ack]]) + + # ACK delimiter bit (recessive) + elif bitnum == (self.last_databit + 18): + self.put(0, 0, self.out_ann, [0, ['ACK delimiter: %d' % can_rx]]) + + # End of frame (EOF), 7 recessive bits + elif bitnum == (self.last_databit + 25): + self.put(0, 0, self.out_ann, [0, ['End of frame', 'EOF']]) + self.reset_variables() + return True + + return False + + # Returns True if the frame ended (EOF), False otherwise. + def decode_standard_frame(self, can_rx, bitnum): + + # Bit 14: RB0 (reserved bit) + # Has to be sent dominant, but receivers should accept recessive too. + if bitnum == 14: + self.put(0, 0, self.out_ann, [0, ['RB0: %d' % can_rx]]) + + # Bit 12: Remote transmission request (RTR) bit + # Data frame: dominant, remote frame: recessive + # Remote frames do not contain a data field. + rtr = 'remote' if self.bits[12] == 1 else 'data' + self.put(0, 0, self.out_ann, [0, ['RTR: %s frame' % rtr]]) + + # Bits 15-18: Data length code (DLC), in number of bytes (0-8). + elif bitnum == 18: + self.dlc = int(''.join(str(d) for d in self.bits[15:18 + 1]), 2) + self.put(0, 0, self.out_ann, [0, ['DLC: %d' % self.dlc]]) + self.last_databit = 18 + (self.dlc * 8) + + # Bits 19-X: Data field (0-8 bytes, depending on DLC) + # The bits within a data byte are transferred MSB-first. + elif bitnum == self.last_databit: + for i in range(self.dlc): + x = 18 + (8 * i) + 1 + b = int(''.join(str(d) for d in self.bits[x:x + 8]), 2) + self.put(0, 0, self.out_ann, + [0, ['Data byte %d: 0x%02x' % (i, b)]]) + + elif bitnum > self.last_databit: + return self.decode_frame_end(can_rx, bitnum) + + return False + + # Returns True if the frame ended (EOF), False otherwise. + def decode_extended_frame(self, can_rx, bitnum): + + # Bits 14-31: Extended identifier (EID[17..0]) + if bitnum == 31: + self.eid = int(''.join(str(d) for d in self.bits[14:]), 2) + self.put(0, 0, self.out_ann, + [0, ['Extended ID: %d (0x%x)' % (self.eid, self.eid)]]) + + self.fullid = self.id << 18 | self.eid + self.put(0, 0, self.out_ann, + [0, ['Full ID: %d (0x%x)' % (self.fullid, self.fullid)]]) + + # Bit 12: Substitute remote request (SRR) bit + self.put(0, 0, self.out_ann, [0, ['SRR: %d' % self.bits[12]]]) + + # Bit 32: Remote transmission request (RTR) bit + # Data frame: dominant, remote frame: recessive + # Remote frames do not contain a data field. + if bitnum == 32: + rtr = 'remote' if can_rx == 1 else 'data' + self.put(0, 0, self.out_ann, [0, ['RTR: %s frame' % rtr]]) + + # Bit 33: RB1 (reserved bit) + elif bitnum == 33: + self.put(0, 0, self.out_ann, [0, ['RB1: %d' % can_rx]]) + + # Bit 34: RB0 (reserved bit) + elif bitnum == 34: + self.put(0, 0, self.out_ann, [0, ['RB0: %d' % can_rx]]) + + # Bits 35-38: Data length code (DLC), in number of bytes (0-8). + elif bitnum == 38: + self.dlc = int(''.join(str(d) for d in self.bits[35:38 + 1]), 2) + self.put(0, 0, self.out_ann, [0, ['DLC: %d' % self.dlc]]) + self.last_databit = 38 + (self.dlc * 8) + + # Bits 39-X: Data field (0-8 bytes, depending on DLC) + # The bits within a data byte are transferred MSB-first. + elif bitnum == self.last_databit: + for i in range(self.dlc): + x = 38 + (8 * i) + 1 + b = int(''.join(str(d) for d in self.bits[x:x + 8]), 2) + self.put(0, 0, self.out_ann, + [0, ['Data byte %d: 0x%02x' % (i, b)]]) + + elif bitnum > self.last_databit: + return self.decode_frame_end(can_rx, bitnum) + + return False + + def handle_bit(self, can_rx): + self.rawbits.append(can_rx) + self.bits.append(can_rx) + + # Get the index of the current CAN frame bit (without stuff bits). + bitnum = len(self.bits) - 1 + + # For debugging. + # self.put(0, 0, self.out_ann, [0, ['Bit %d (CAN bit %d): %d' % \ + # (self.curbit, bitnum, can_rx)]]) + + # If this is a stuff bit, remove it from self.bits and ignore it. + if self.is_stuff_bit(): + self.curbit += 1 # Increase self.curbit (bitnum is not affected). + return + + # Bit 0: Start of frame (SOF) bit + if bitnum == 0: + if can_rx == 0: + self.put(0, 0, self.out_ann, [0, ['Start of frame', 'SOF']]) + else: + self.put(self.ss, self.es, self.out_ann, + [1, ['Start of frame (SOF) must be a dominant bit']]) + + # Bits 1-11: Identifier (ID[10..0]) + # The bits ID[10..4] must NOT be all recessive. + elif bitnum == 11: + self.id = int(''.join(str(d) for d in self.bits[1:]), 2) + self.put(0, 0, self.out_ann, + [0, ['ID: %d (0x%x)' % (self.id, self.id)]]) + + # RTR or SRR bit, depending on frame type (gets handled later). + elif bitnum == 12: + # self.put(0, 0, self.out_ann, [0, ['RTR/SRR: %d' % can_rx]]) + pass + + # Bit 13: Identifier extension (IDE) bit + # Standard frame: dominant, extended frame: recessive + elif bitnum == 13: + ide = self.frame_type = 'standard' if can_rx == 0 else 'extended' + self.put(0, 0, self.out_ann, [0, ['IDE: %s frame' % ide]]) + + # Bits 14-X: Frame-type dependent, passed to the resp. handlers. + elif bitnum >= 14: + if self.frame_type == 'standard': + done = self.decode_standard_frame(can_rx, bitnum) + else: + done = self.decode_extended_frame(can_rx, bitnum) + + # The handlers return True if a frame ended (EOF). + if done: + return + + # After a frame there are 3 intermission bits (recessive). + # After these bits, the bus is considered free. + + self.curbit += 1 + + def decode(self, ss, es, data): + for (self.samplenum, pins) in data: + + (can_rx,) = pins + + # State machine. + if self.state == 'IDLE': + # Wait for a dominant state (logic 0) on the bus. + if can_rx == 1: + continue + self.sof = self.samplenum + # self.put(self.sof, self.sof, self.out_ann, [0, ['SOF']]) + self.state = 'GET BITS' + elif self.state == 'GET BITS': + # Wait until we're in the correct bit/sampling position. + if not self.reached_bit(self.curbit): + continue + self.handle_bit(can_rx) + else: + raise Exception("Invalid state: %s" % self.state) + |