import ctypes as ct
from collections import namedtuple
from .. import VersionNumber
from ..frame import LINFrame
from .enums import ChannelType, MessageFlag, Setup
from .structures import MessageInfo
from .wrapper import dll
FirmwareVersion = namedtuple('FirmwareVersion', 'boot_version app_version')
[docs]def openChannel(channel_number, channel_type, bps=None):
"""Open a channel to a LIN interface.
Args:
channel_number (`int`): The number of the channel. This is the same
channel number as used by `.canlib.openChannel`.
channel_type (`ChannelType`): Whether the LIN interface will be a
master or slave.
bps (`int` or `None`): If not `None`, `Channel.setBitrate` will be called with
this value before the channel is returned.
Returns:
(`Channel`): The opened channel
Note:
For DRV Lin: The cable must be powered and connected to a LAPcan channel.
For Kvaser LIN Leaf: The Leaf must be powered from the LIN side.
"""
handle = dll.linOpenChannel(channel_number, channel_type)
channel = Channel(handle)
if bps is not None:
channel.setBitrate(bps)
return channel
[docs]def openMaster(channel_number, bps=None):
"""Open a channel as a master
This function simply calls `openChannel` with `channel_type` set to
`ChannelType.MASTER`.
"""
return openChannel(channel_number, ChannelType.MASTER, bps=bps)
[docs]def openSlave(channel_number, bps=None):
"""Open a channel as a slave
This function simply calls `openChannel` with `channel_type` set to
`ChannelType.SLAVE`.
"""
return openChannel(channel_number, ChannelType.SLAVE, bps=bps)
[docs]class Channel:
"""A LINlib channel
This class is normally instantiated with `openMaster` or `openSlave`.
Channels are automatically closed on garbage collection, and can
also be used as context managers in which case they close as soon as the
context exits.
"""
def __init__(self, handle):
self.handle = handle
def __del__(self):
self.close()
def __enter__(self):
return self
def __exit__(self, type, value, traceback):
self.close()
# def readTimer():
# raise NotImplementedError
[docs] def busOff(self):
"""Go bus off
This function deactivates the LIN interface. It will not participate
further in the LIN bus traffic.
"""
dll.linBusOff(self.handle)
[docs] def busOn(self):
"""Go bus on
This function activates the LIN interface.
"""
dll.linBusOn(self.handle)
[docs] def clearMessage(self, msg_id):
"""Clear a message buffer for a LIN slave
The message buffer will not answer next time it is polled.
"""
dll.linClearMessage(self.handle, msg_id)
[docs] def close(self):
"""Close this LINlib channel
Closes an open handle to a LIN channel.
Note:
It is normally not necessary to call this function directly, as the
internal handle is automatically closed when the `Channel` object
is garbage collected.
.. versionadded:: 1.6
"""
if self.handle is not None:
self.busOff()
dll.linClose(self.handle)
self.handle = None
[docs] def getCanHandle(self):
"""Return the CAN handle given an open LIN handle"""
can_handle = ct.c_uint()
dll.linGetCanHandle(self.handle, ct.byref(can_handle))
return can_handle.value
[docs] def getFirmwareVersion(self):
"""Retrieve the firmware version from the LIN interface
Returns a `FirmwareVersion` namedtuple containing `boot_version` and
`app_version` that are `canlib.VersionNumber` namedtuples. If only one of
these is needed, the return value can be unpacked as such::
boot_ver, app_ver = channel.getFirmwareVersion()
Note:
For newer interfaces use `getChannelData` with
`ChannelData.CARD_FIRMWARE_REV` instead.
The version numbers aren't valid until `Channel.busOn` has been
called.
The firmware in the LIN interface is divided into two parts, the
boot code and the application. The boot code is used only when
reprogramming (reflashing) the LIN interface. The application
handles all LIN communication.
Version numbers are, since the precambric era, divided into a major
version number, a minor version number and a build
number. These are usually written like, for example,
3.2.12. Here the major number is 3, the minor number 2 and the
build number 12.
"""
bootver = [ct.c_ubyte() for i in range(3)]
appver = [ct.c_ubyte() for i in range(3)]
# In Python 2, you can't use '*' on more than one argument
refs = tuple(ct.byref(ub) for ub in bootver) + tuple(ct.byref(ub) for ub in appver)
dll.linGetFirmwareVersion(self.handle, *refs)
bootver = [v.value for v in bootver]
appver = [v.value for v in appver]
return FirmwareVersion(
boot_version=VersionNumber(*bootver),
app_version=VersionNumber(*appver),
)
[docs] def read(self, timeout=0):
"""Read a message from the LIN interface
If a message is available for reception, linOK is returned. This is a
non-blocking call. It waits until a message is received in the LIN
interface, or the specified timeout period elapses.
This may return a frame sent by `writeMessage` or `writeWakeup`.
Note:
This call will also return echoes of what the LIN interface is
transmitting with `writeMessage`. In other words, the LIN
interface can hear itself.
Args:
timeout (`int`): Timeout in milliseconds.
Returns:
(`canlib.LINFrame`)
"""
id_ = ct.c_uint()
_MAX_SIZE = 8
msg = ct.create_string_buffer(_MAX_SIZE)
dlc = ct.c_uint()
flags = ct.c_uint()
info = MessageInfo()
dll.linReadMessageWait(
self.handle,
ct.byref(id_),
ct.byref(msg),
ct.byref(dlc),
ct.byref(flags),
ct.byref(info),
timeout,
)
length = min(_MAX_SIZE, dlc.value)
return LINFrame(
id_=id_.value,
data=bytearray(msg.raw[:length]),
dlc=dlc.value,
flags=MessageFlag(int(flags.value)), # in Python 2, we get a long
info=info,
)
[docs] def requestMessage(self, msgid):
"""Request a message from a slave
This function writes a LIN message header to the LIN bus. A slave in
the system is then expected to fill in the header with data.
Note:
This call is only available in master mode.
"""
dll.linRequestMessage(self.handle, msgid)
[docs] def setBitrate(self, bps):
"""Set the bitrate in bits per second
This function sets the bit rate for a master, or the initial bit rate
for a slave. The LIN interface should not be on-bus when this function
is called.
Note:
The LIN Interface should not be on bus.
Supported bit rates are 1000 - 20000 bits per second.
"""
assert 1000 <= bps <= 20000 # qqqdaca nicer error
dll.linSetBitrate(self.handle, bps)
[docs] def setupIllegalMessage(self, msgid, disturb_flags, delay):
"""Create a corrupted LIN message
Using this function, it is possible to use the LIN interface to create
corrupted LIN messages. You call the function once for each LIN
identifier that should be affected.
To return to normal mode, either restart the LIN interface (by going
off bus and on the bus again) or call the function with delay and
disturb_flags set to zero.
Args:
msgid (`int`): The identifier of the LIN message
disturb_flags (`MessageDisturb`): One or more of the
`MessageDisturb` flags.
delay (`int`): The delay parameter will result in a delay of this
many bittimes after the header and before the first data byte.
Note:
The LIN Interface must be on bus for this command to work.
It is supported in firmware version 2.4.1 and later.
"""
dll.linSetupIllegalMessage(self.handle, msgid, disturb_flags, delay)
[docs] def setupLIN(self, flags=Setup.VARIABLE_DLC, bps=0):
"""Setup the LIN interface
This function changes various settings on a LIN Interface that is on
bus. When going on bus, the bit rate and the flag values listed below
are set to the default value (either as hard-coded in the firmware, or
as stored in the non-volatile memory of the LIN Interface).
With this function, you can do one or more of the following things:
* Select checksum according to LIN 2.0
* Turn variable message length off. The message length then will depend
on the message ID.
In master mode it is also possible to change the bit rate without going
off bus first.
Note:
The LIN Interface must be on bus for this command to work.
It is supported in firmware version 2.5.1 and later.
For LIN 2.0 compliance, you must specify both LIN_ENHANCED_CHECKSUM
and LIN_VARIABLE_DLC.
Args:
flags (`Setup`): One or more of the `Setup` flags
bps (`int`): The bit rate in bits per second. This parameter can be
used only in master mode. The bit rate is set without going off
bus.
"""
dll.linSetupLIN(self.handle, flags, bps)
[docs] def updateMessage(self, frame):
"""Update a message buffer in a slave
This function updates a message buffer in a slave. The contents of the
message buffer will be used the next time the slave is polled for the
specified LIN message id.
Note:
The LIN Interface must be on bus.
Args:
frame (`canlib.Frame`): The information to be updated. Only the `.Frame.id`,
`.Frame.data`, and `.Frame.dlc` attributes are used. Note that the frame can,
but not need not, be a `.LINFrame`.
"""
void_p_data = (ct.c_ubyte * frame.dlc)(*frame.data)
dll.linUpdateMessage(self.handle, frame.id, void_p_data, frame.dlc)
[docs] def writeMessage(self, frame):
"""Write a LIN message
Write a LIN message. It is advisable to wait until the message is
echoed by `read` before transmitting a new message, or in
case of a schedule table being used, transmit the next message when the
previous one is known to be complete.
Note:
Only available in master mode
Args:
frame (`canlib.Frame`) :: The information to be updated. Only the `.Frame.id`,
`.Frame.data`, and `.Frame.dlc` attributes are used. Note that the frame can,
but not need not, be a `.LINFrame`.
"""
void_p_data = (ct.c_ubyte * frame.dlc)(*frame.data)
dll.linWriteMessage(self.handle, frame.id, void_p_data, frame.dlc)
[docs] def writeSync(self, timeout):
"""Make sure all message transmitted to the interface have been received
*timeout* is in milliseconds.
When messages are transmitted to the LIN Interface, they are queued by
the driver before appearing on the CAN bus.
If the LIN Interface is in master mode and a LIN message has been
transmitted with `writeMessage`, this function will return when the LIN
Interface has received the message. If another LIN message is being
received or transmitted, the message will not be transmitted on the LIN
bus at once. And even if the LIN Interface is idle, the header of the
new message will just have been started when `writeSync` returns.
After calling `updateMessage` and `clearMessage` for a slave, this
function is enough to know that the LIN Interface is updated.
After `writeMessage`, it is advisable to wait until the message is
echoed by `read` before transmitting a new message, or in case
of a schedule table being used, transmit the next message when the
previous one is known to be complete.
When, in master mode, a message should be transmitted after a poll
(reception) is done, it might be necessary to call `writeMessage`
before the result is received via `read` as the LIN Interface
waits up to the maximum frame length before knowing a received message
is complete. A new message to transmit will force completion if the
currently received one.
"""
dll.linWriteSync(self.handle, timeout)
[docs] def writeWakeup(self, count=0, interval=1):
"""Write one or more wakeup frames
If *count* is zero (the default), one single wakeup frame is
transmitted. If *count* > 1, several wakeup frames are transmitted
spaced with *interval* bit times. The LIN interface will interrupt the
sequence when a LIN message or another command is received. The stream
of wakeups will be recived as incoming messages with the
`MessageFlag.RX` flag.
Args:
count (`int`): The number of wakeup frames to send.
interval (`int`): The time, in bit times, between the wakeup frames.
"""
dll.linWriteWakeup(self.handle, count, interval)