Source code for can.interfaces.pcan.pcan

#!/usr/bin/env python
# coding: utf-8

Enable basic CAN over a PCAN USB device.

from __future__ import absolute_import, print_function

import logging
import sys
import time

import can
from can import CanError, Message, BusABC
from .PCANBasic import *
from can.bus import BusState

boottimeEpoch = 0
    import uptime
    import datetime
    boottimeEpoch = (uptime.boottime() - datetime.datetime.utcfromtimestamp(0)).total_seconds()
    boottimeEpoch = 0

    # Try builtin Python 3 Windows API
    from _overlapped import CreateEvent
    from _winapi import WaitForSingleObject, WAIT_OBJECT_0, INFINITE
    HAS_EVENTS = True
except ImportError:
        # Try pywin32 package
        from win32event import CreateEvent
        from win32event import WaitForSingleObject, WAIT_OBJECT_0, INFINITE
        HAS_EVENTS = True
    except ImportError:
        # Use polling instead
        HAS_EVENTS = False

    # new in 3.3
    timeout_clock = time.perf_counter
except AttributeError:
    # deprecated in 3.3
    timeout_clock = time.clock

# Set up logging
log = logging.getLogger('can.pcan')

pcan_bitrate_objs = {1000000 : PCAN_BAUD_1M,
                      800000 : PCAN_BAUD_800K,
                      500000 : PCAN_BAUD_500K,
                      250000 : PCAN_BAUD_250K,
                      125000 : PCAN_BAUD_125K,
                      100000 : PCAN_BAUD_100K,
                       95000 : PCAN_BAUD_95K,
                       83000 : PCAN_BAUD_83K,
                       50000 : PCAN_BAUD_50K,
                       47000 : PCAN_BAUD_47K,
                       33000 : PCAN_BAUD_33K,
                       20000 : PCAN_BAUD_20K,
                       10000 : PCAN_BAUD_10K,
                        5000 : PCAN_BAUD_5K}

[docs]class PcanBus(BusABC): def __init__(self, channel, state=BusState.ACTIVE, *args, **kwargs): """A PCAN USB interface to CAN. On top of the usual :class:`~can.Bus` methods provided, the PCAN interface includes the :meth:`~can.interface.pcan.PcanBus.flash()` and :meth:`~can.interface.pcan.PcanBus.status()` methods. :param str channel: The can interface name. An example would be 'PCAN_USBBUS1' :param BusState state: BusState of the channel. Default is ACTIVE :param int bitrate: Bitrate of channel in bit/s. Default is 500 kbit/s. """ if not channel: raise ArgumentError("Must specify a PCAN channel") else: self.channel_info = channel bitrate = kwargs.get('bitrate', 500000) pcan_bitrate = pcan_bitrate_objs.get(bitrate, PCAN_BAUD_500K) hwtype = PCAN_TYPE_ISA ioport = 0x02A0 interrupt = 11 self.m_objPCANBasic = PCANBasic() self.m_PcanHandle = globals()[channel] if state is BusState.ACTIVE or BusState.PASSIVE: self._state = state else: raise ArgumentError("BusState must be Active or Passive") result = self.m_objPCANBasic.Initialize(self.m_PcanHandle, pcan_bitrate, hwtype, ioport, interrupt) if result != PCAN_ERROR_OK: raise PcanError(self._get_formatted_error(result)) if HAS_EVENTS: self._recv_event = CreateEvent(None, 0, 0, None) result = self.m_objPCANBasic.SetValue( self.m_PcanHandle, PCAN_RECEIVE_EVENT, self._recv_event) if result != PCAN_ERROR_OK: raise PcanError(self._get_formatted_error(result)) super(PcanBus, self).__init__(channel=channel, *args, **kwargs) def _get_formatted_error(self, error): """ Gets the text using the GetErrorText API function. If the function call succeeds, the translated error is returned. If it fails, a text describing the current error is returned. Multiple errors may be present in which case their individual messages are included in the return string, one line per error. """ def bits(n): """TODO: document""" while n: b = n & (~n+1) yield b n ^= b stsReturn = self.m_objPCANBasic.GetErrorText(error, 0) if stsReturn[0] != PCAN_ERROR_OK: strings = [] for b in bits(error): stsReturn = self.m_objPCANBasic.GetErrorText(b, 0) if stsReturn[0] != PCAN_ERROR_OK: text = "An error occurred. Error-code's text ({0:X}h) couldn't be retrieved".format(error) else: text = stsReturn[1].decode('utf-8', errors='replace') strings.append(text) complete_text = '\n'.join(strings) else: complete_text = stsReturn[1].decode('utf-8', errors='replace') return complete_text
[docs] def status(self): """ Query the PCAN bus status. :return: The status code. See values in """ return self.m_objPCANBasic.GetStatus(self.m_PcanHandle)
[docs] def status_is_ok(self): """ Convenience method to check that the bus status is OK """ status = self.status() return status == PCAN_ERROR_OK
[docs] def reset(self): """ Command the PCAN driver to reset the bus after an error. """ status = self.m_objPCANBasic.Reset(self.m_PcanHandle) return status == PCAN_ERROR_OK
def _recv_internal(self, timeout): if HAS_EVENTS: # We will utilize events for the timeout handling timeout_ms = int(timeout * 1000) if timeout is not None else INFINITE elif timeout is not None: # Calculate max time end_time = timeout_clock() + timeout log.debug("Trying to read a msg") result = None while result is None: result = self.m_objPCANBasic.Read(self.m_PcanHandle) if result[0] == PCAN_ERROR_QRCVEMPTY: if HAS_EVENTS: result = None val = WaitForSingleObject(self._recv_event, timeout_ms) if val != WAIT_OBJECT_0: return None, False elif timeout is not None and timeout_clock() >= end_time: return None, False else: result = None time.sleep(0.001) elif result[0] & (PCAN_ERROR_BUSLIGHT | PCAN_ERROR_BUSHEAVY): log.warning(self._get_formatted_error(result[0])) return None, False elif result[0] != PCAN_ERROR_OK: raise PcanError(self._get_formatted_error(result[0])) theMsg = result[1] itsTimeStamp = result[2] log.debug("Received a message") bIsRTR = (theMsg.MSGTYPE & PCAN_MESSAGE_RTR.value) == PCAN_MESSAGE_RTR.value bIsExt = (theMsg.MSGTYPE & PCAN_MESSAGE_EXTENDED.value) == PCAN_MESSAGE_EXTENDED.value if bIsExt: #rx_msg.id_type = ID_TYPE_EXTENDED log.debug("CAN: Extended") else: #rx_msg.id_type = ID_TYPE_STANDARD log.debug("CAN: Standard") dlc = theMsg.LEN timestamp = boottimeEpoch + ((itsTimeStamp.micros + (1000 * itsTimeStamp.millis)) / (1000.0 * 1000.0)) rx_msg = Message(timestamp=timestamp, arbitration_id=theMsg.ID, extended_id=bIsExt, is_remote_frame=bIsRTR, dlc=dlc, data=theMsg.DATA[:dlc]) return rx_msg, False
[docs] def send(self, msg, timeout=None): if msg.id_type: msgType = PCAN_MESSAGE_EXTENDED else: msgType = PCAN_MESSAGE_STANDARD # create a TPCANMsg message structure CANMsg = TPCANMsg() # configure the message. ID, Length of data, message type and data CANMsg.ID = msg.arbitration_id CANMsg.LEN = msg.dlc CANMsg.MSGTYPE = msgType # if a remote frame will be sent, data bytes are not important. if msg.is_remote_frame: CANMsg.MSGTYPE = msgType.value | PCAN_MESSAGE_RTR.value else: # copy data for i in range(CANMsg.LEN): CANMsg.DATA[i] =[i] log.debug("Data: %s", log.debug("Type: %s", type( result = self.m_objPCANBasic.Write(self.m_PcanHandle, CANMsg) if result != PCAN_ERROR_OK: raise PcanError("Failed to send: " + self._get_formatted_error(result))
[docs] def flash(self, flash): """ Turn on or off flashing of the device's LED for physical identification purposes. """ self.m_objPCANBasic.SetValue(self.m_PcanHandle, PCAN_CHANNEL_IDENTIFYING, bool(flash))
[docs] def shutdown(self): super(PcanBus, self).shutdown() self.m_objPCANBasic.Uninitialize(self.m_PcanHandle)
@property def state(self): return self._state @state.setter def state(self, new_state): self._state = new_state if new_state is BusState.ACTIVE: self.m_objPCANBasic.SetValue(self.m_PcanHandle, PCAN_LISTEN_ONLY, PCAN_PARAMETER_OFF) if new_state is BusState.PASSIVE: # When this mode is set, the CAN controller does not take part on active events (eg. transmit CAN messages) # but stays in a passive mode (CAN monitor), in which it can analyse the traffic on the CAN bus used by a # PCAN channel. See also the Philips Data Sheet "SJA1000 Stand-alone CAN controller". self.m_objPCANBasic.SetValue(self.m_PcanHandle, PCAN_LISTEN_ONLY, PCAN_PARAMETER_ON)
class PcanError(CanError): """ TODO: add docs """ pass