"""
NI-XNET interface module.
Implementation references:
NI-XNET Hardware and Software Manual: https://www.ni.com/pdf/manuals/372840h.pdf
NI-XNET Python implementation: https://github.com/ni/nixnet-python
Authors: Javier Rubio Giménez <jvrr20@gmail.com>, Jose A. Escobar <joseleescobar@hotmail.com>
"""
import logging
import os
import time
import warnings
from queue import SimpleQueue
from types import ModuleType
from typing import Any, List, Optional, Tuple, Union
import can.typechecking
from can import BitTiming, BitTimingFd, BusABC, CanProtocol, Message
from can.exceptions import (
CanInitializationError,
CanInterfaceNotImplementedError,
CanOperationError,
)
from can.util import check_or_adjust_timing_clock, deprecated_args_alias
logger = logging.getLogger(__name__)
nixnet: Optional[ModuleType] = None
try:
import nixnet # type: ignore
import nixnet.constants # type: ignore
import nixnet.system # type: ignore
import nixnet.types # type: ignore
except Exception as exc:
logger.warning("Could not import nixnet: %s", exc)
[docs]
class NiXNETcanBus(BusABC):
"""
The CAN Bus implemented for the NI-XNET interface.
"""
@deprecated_args_alias(
deprecation_start="4.2.0",
deprecation_end="5.0.0",
brs=None,
log_errors=None,
)
def __init__(
self,
channel: str = "CAN1",
bitrate: int = 500_000,
timing: Optional[Union[BitTiming, BitTimingFd]] = None,
can_filters: Optional[can.typechecking.CanFilters] = None,
receive_own_messages: bool = False,
can_termination: bool = False,
fd: bool = False,
fd_bitrate: Optional[int] = None,
poll_interval: float = 0.001,
**kwargs: Any,
) -> None:
"""
:param str channel:
Name of the object to open (e.g. 'CAN0')
:param int bitrate:
Bitrate in bits/s
:param timing:
Optional :class:`~can.BitTiming` or :class:`~can.BitTimingFd` instance
to use for custom bit timing setting. The `f_clock` value of the timing
instance must be set to 40_000_000 (40MHz).
If this parameter is provided, it takes precedence over all other
timing-related parameters like `bitrate`, `fd_bitrate` and `fd`.
:param list can_filters:
See :meth:`can.BusABC.set_filters`.
:param receive_own_messages:
Enable self-reception of sent messages.
:param poll_interval:
Poll interval in seconds.
:raises ~can.exceptions.CanInitializationError:
If starting communication fails
"""
if os.name != "nt" and not kwargs.get("_testing", False):
raise CanInterfaceNotImplementedError(
f"The NI-XNET interface is only supported on Windows, "
f'but you are running "{os.name}"'
)
if nixnet is None:
raise CanInterfaceNotImplementedError("The NI-XNET API has not been loaded")
self.nixnet = nixnet
self._rx_queue = SimpleQueue() # type: ignore[var-annotated]
self.channel = channel
self.channel_info = "NI-XNET: " + channel
self.poll_interval = poll_interval
is_fd = isinstance(timing, BitTimingFd) if timing else fd
self._can_protocol = CanProtocol.CAN_FD if is_fd else CanProtocol.CAN_20
# Set database for the initialization
database_name = ":can_fd_brs:" if is_fd else ":memory:"
try:
# We need two sessions for this application,
# one to send frames and another to receive them
self._session_send = nixnet.session.FrameOutStreamSession(
channel, database_name=database_name
)
self._session_receive = nixnet.session.FrameInStreamSession(
channel, database_name=database_name
)
self._interface = self._session_send.intf
# set interface properties
self._interface.can_lstn_only = kwargs.get("listen_only", False)
self._interface.echo_tx = receive_own_messages
self._interface.bus_err_to_in_strm = True
if isinstance(timing, BitTimingFd):
timing = check_or_adjust_timing_clock(timing, [40_000_000])
custom_nom_baud_rate = ( # nxPropSession_IntfBaudRate64
0xA0000000
+ (timing.nom_tq << 32)
+ (timing.nom_sjw - 1 << 16)
+ (timing.nom_tseg1 - 1 << 8)
+ (timing.nom_tseg2 - 1)
)
custom_data_baud_rate = ( # nxPropSession_IntfCanFdBaudRate64
0xA0000000
+ (timing.data_tq << 13)
+ (timing.data_tseg1 - 1 << 8)
+ (timing.data_tseg2 - 1 << 4)
+ (timing.data_sjw - 1)
)
self._interface.baud_rate = custom_nom_baud_rate
self._interface.can_fd_baud_rate = custom_data_baud_rate
elif isinstance(timing, BitTiming):
timing = check_or_adjust_timing_clock(timing, [40_000_000])
custom_baud_rate = ( # nxPropSession_IntfBaudRate64
0xA0000000
+ (timing.tq << 32)
+ (timing.sjw - 1 << 16)
+ (timing.tseg1 - 1 << 8)
+ (timing.tseg2 - 1)
)
self._interface.baud_rate = custom_baud_rate
else:
# See page 1017 of NI-XNET Hardware and Software Manual
# to set custom can configuration
if bitrate:
self._interface.baud_rate = bitrate
if is_fd:
# See page 951 of NI-XNET Hardware and Software Manual
# to set custom can configuration
self._interface.can_fd_baud_rate = fd_bitrate or bitrate
_can_termination = (
nixnet.constants.CanTerm.ON
if can_termination
else nixnet.constants.CanTerm.OFF
)
self._interface.can_term = _can_termination
# self._session_receive.queue_size = 512
# Once that all the parameters have been set, we start the sessions
self._session_send.start()
self._session_receive.start()
except nixnet.errors.XnetError as error:
raise CanInitializationError(
f"{error.args[0]} ({error.error_type})", error.error_code
) from None
self._is_filtered = False
super().__init__(
channel=channel,
can_filters=can_filters,
bitrate=bitrate,
**kwargs,
)
@property
def fd(self) -> bool:
warnings.warn(
"The NiXNETcanBus.fd property is deprecated and superseded by "
"BusABC.protocol. It is scheduled for removal in version 5.0.",
DeprecationWarning,
)
return self._can_protocol is CanProtocol.CAN_FD
def _recv_internal(
self, timeout: Optional[float]
) -> Tuple[Optional[Message], bool]:
end_time = time.perf_counter() + timeout if timeout is not None else None
while True:
# try to read all available frames
for frame in self._session_receive.frames.read(1024, timeout=0):
self._rx_queue.put_nowait(frame)
if self._rx_queue.qsize():
break
# check for timeout
if end_time is not None and time.perf_counter() > end_time:
return None, False
# Wait a short time until we try to read again
time.sleep(self.poll_interval)
can_frame = self._rx_queue.get_nowait()
# Timestamp should be converted from raw frame format(100ns increment
# from(12:00 a.m. January 1 1601 Coordinated Universal Time (UTC))
# to epoch time(number of seconds from January 1, 1970 (midnight UTC/GMT))
timestamp = can_frame.timestamp * 1e-7 - 11_644_473_600
if can_frame.type is self.nixnet.constants.FrameType.CAN_BUS_ERROR:
msg = Message(
timestamp=timestamp,
channel=self.channel,
is_error_frame=True,
)
else:
msg = Message(
timestamp=timestamp,
channel=self.channel,
is_remote_frame=can_frame.type
is self.nixnet.constants.FrameType.CAN_REMOTE,
is_error_frame=False,
is_fd=(
can_frame.type is self.nixnet.constants.FrameType.CANFD_DATA
or can_frame.type is self.nixnet.constants.FrameType.CANFDBRS_DATA
),
bitrate_switch=(
can_frame.type is self.nixnet.constants.FrameType.CANFDBRS_DATA
),
is_extended_id=can_frame.identifier.extended,
# Get identifier from CanIdentifier structure
arbitration_id=can_frame.identifier.identifier,
dlc=len(can_frame.payload),
data=can_frame.payload,
is_rx=not can_frame.echo,
)
return msg, False
[docs]
def send(self, msg: Message, timeout: Optional[float] = None) -> None:
"""
Send a message using NI-XNET.
:param can.Message msg:
Message to send
:param float timeout:
Max time to wait for the device to be ready in seconds, None if time is infinite
:raises can.exceptions.CanOperationError:
If writing to transmit buffer fails.
It does not wait for message to be ACKed currently.
"""
if timeout is None:
timeout = self.nixnet.constants.TIMEOUT_INFINITE
if msg.is_remote_frame:
type_message = self.nixnet.constants.FrameType.CAN_REMOTE
elif msg.is_error_frame:
type_message = self.nixnet.constants.FrameType.CAN_BUS_ERROR
elif msg.is_fd:
if msg.bitrate_switch:
type_message = self.nixnet.constants.FrameType.CANFDBRS_DATA
else:
type_message = self.nixnet.constants.FrameType.CANFD_DATA
else:
type_message = self.nixnet.constants.FrameType.CAN_DATA
can_frame = self.nixnet.types.CanFrame(
self.nixnet.types.CanIdentifier(msg.arbitration_id, msg.is_extended_id),
type=type_message,
payload=msg.data,
)
try:
self._session_send.frames.write([can_frame], timeout)
except self.nixnet.errors.XnetError as error:
raise CanOperationError(
f"{error.args[0]} ({error.error_type})", error.error_code
) from None
[docs]
def reset(self) -> None:
"""
Resets network interface. Stops network interface, then resets the CAN
chip to clear the CAN error counters (clear error passive state).
Resetting includes clearing all entries from read and write queues.
"""
self._session_send.flush()
self._session_receive.flush()
self._session_send.stop()
self._session_receive.stop()
self._session_send.start()
self._session_receive.start()
[docs]
def shutdown(self) -> None:
"""Close object."""
super().shutdown()
if hasattr(self, "_session_send"):
self._session_send.flush()
self._session_send.stop()
self._session_send.close()
if hasattr(self, "_session_receive"):
self._session_receive.flush()
self._session_receive.stop()
self._session_receive.close()
@staticmethod
def _detect_available_configs() -> List[can.typechecking.AutoDetectedConfig]:
configs = []
try:
with nixnet.system.System() as nixnet_system: # type: ignore[union-attr]
for interface in nixnet_system.intf_refs_can:
channel = str(interface)
logger.debug(
"Found channel index %d: %s", interface.port_num, channel
)
configs.append(
{
"interface": "nixnet",
"channel": channel,
"can_term_available": interface.can_term_cap
is nixnet.constants.CanTermCap.YES, # type: ignore[union-attr]
"supports_fd": interface.can_tcvr_cap
is nixnet.constants.CanTcvrCap.HS, # type: ignore[union-attr]
}
)
except Exception as error:
logger.debug("An error occured while searching for configs: %s", str(error))
return configs # type: ignore