Single millisecond send resolution with python-can, Vector

[ack-kullum]

python version: 3.9.13, python-can version: 4.0.0

I am trying to send a CAN message every millisecond using python-can to access Vector's CANalyzer software. Using the code below, I would expect to see a message every millisecond:

import can
import time
import logging

bus = can.interface.Bus(bustype="vector", channel=0, bitrate=500000, app_name='CANalyzer')

def periodic_send(msg, bus):
    task = bus.send_periodic(msg, 0.001)
    assert isinstance(task, can.CyclicSendTaskABC)

    return task

tasks = []

msg = can.Message(arbitration_id=0xCE, data=[1, 1, 1, 1], is_extended_id=False)
tasks.append(periodic_send(msg,bus))

time.sleep(200)

However, when I look at the signal in CANalyzer, it shows the message being sent every 15ms or so (blue measurement cursor is first sample, orange is second):

I have also tried managing timing directly and have similarly been unable to achieve single millisecond intervals. Is this possible with python-can?

[danielhrisca]

Does it make any difference if you patch time before importing can

import sys

if sys.platform == "win32":
    import time

    from win_precise_time import sleep as wpsleep
    from win_precise_time import time as wptime

    time.sleep = wpsleep
    time.time = wptime

import can

see https://pypi.org/project/win-precise-time/

[pierreluctg]

On Windows, which I assume you are since you are using Vector, python-can not using time.sleep in most setup.
See https://github.com/hardbyte/python-can/blob/main/can/broadcastmanager.py#L327

On of the reason to use win32event is exactly for the reason that you are raising. time.sleep (prior to Python 3.12) has a resolution of 15.6 ms.

Now you should try to figure out why in your setup USE_WINDOWS_EVENTS is False
https://github.com/hardbyte/python-can/blob/main/can/broadcastmanager.py#L23