Source code for can.interfaces.pcan

"""
Enable basic can over a PCAN USB device.

"""
import logging
import sys

logger = logging.getLogger(__name__)

from can.interfaces.PCANBasic import *
from can.bus import BusABC
from can.message import Message
from can import CanError
import time

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

if sys.version_info >= (3, 3):
    # new in 3.3
    timeout_clock = time.perf_counter
else:
    # deprecated in 3.3
    timeout_clock = time.clock

# Set up logging
logging.basicConfig(level=logging.WARNING)
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, *args, **kwargs): """A PCAN USB interface to CAN. On top of the usual :class:`~can.Bus` methods provided, the PCAN interface includes the `flash()` and `status()` methods. :param str channel: The can interface name. An example would be PCAN_USBBUS1 :param int bitrate: Bitrate of channel in bit/s. Default is 500 Kbs """ if channel is None or 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] 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)) super(PcanBus, self).__init__(*args, **kwargs) def _get_formatted_error(self, error): """ Gets the text using the GetErrorText API function If the function 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): 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') strings.append(text) complete_text = '\n'.join(strings) else: complete_text = stsReturn[1].decode('utf-8') return complete_text
[docs] def status(self): """ Query the PCAN bus status. :return: The status code. See values in pcan_constants.py """ return self.m_objPCANBasic.GetStatus(self.channel_info)
[docs] def status_is_ok(self): """ Convenience method to check that the bus status is OK """ status = self.status() return status == PCAN_ERROR_OK
def reset(self): # Command the PCAN driver to reset the bus after an error. status = self.m_objPCANBasic.Reset(self.channel_info) return status == PCAN_ERROR_OK def recv(self, timeout=None): start_time = timeout_clock() if timeout is None: timeout = 0 rx_msg = Message() 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 or result[0] == PCAN_ERROR_BUSLIGHT or result[0] == PCAN_ERROR_BUSHEAVY: if timeout_clock() - start_time >= timeout: return None else: result = None time.sleep(0.001) 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 def send(self, msg): 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 = len(msg.data) 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] = msg.data[i] log.debug("Data: %s", msg.data) log.debug("Type: %s", type(msg.data)) 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.channel_info, PCAN_CHANNEL_IDENTIFYING, bool(flash))
def shutdown(self): self.m_objPCANBasic.Uninitialize(self.m_PcanHandle)
class PcanError(CanError): pass