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#!/usr/bin/env python3
"""
Exposes several methods for transmitting cyclic messages.
20/09/13
"""
import can
import abc
import logging
log = logging.getLogger('can.bcm')
log.debug("Loading base broadcast manager functionality")
class CyclicTask(object):
def stop(self):
"""Cancel the periodic task"""
raise NotImplementedError()
def start(self):
"""Once stopped a task can be restarted"""
raise NotImplementedError()
class CyclicSendTaskABC(CyclicTask):
def __init__(self, channel, message, period):
"""
:param str channel: The name of the CAN channel to connect to.
:param message: The :class:`can.Message` to be sent periodically.
:param float period: The rate in seconds at which to send the message.
"""
self.can_id = message.arbitration_id
self.period = period
@abc.abstractmethod
def stop(self):
"""Send a TX_DELETE message to the broadcast manager to cancel this task.
This will delete the entry for the transmission of the CAN message
specified.
"""
@abc.abstractmethod
def modify_data(self, message):
"""Update the contents of this periodically sent message without altering
the timing.
:param message: The :class:`~can.Message` with new :attr:`Message.data`.
Note it must have the same :attr:`~can.Message.arbitration_id`.
"""
class MultiRateCyclicSendTaskABC(CyclicSendTaskABC):
"""Exposes more of the full power of the TX_SETUP opcode.
Transmits a message `count` times at `initial_period` then
continues to transmit message at `subsequent_period`.
"""
def __init__(self, channel, message, count, initial_period, subsequent_period):
super(MultiRateCyclicSendTaskABC, self).__init__(channel, message, subsequent_period)
def send_periodic(channel, message, period):
"""
Send a message every `period` seconds on the given channel.
"""
return can.interface.CyclicSendTask(channel, message, period)
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