From mboxrd@z Thu Jan 1 00:00:00 1970 From: Patrick Menschel Subject: Re: Measuring latency of CAN messages in SocketCAN Date: Thu, 6 Oct 2016 21:48:57 +0200 Message-ID: References: Mime-Version: 1.0 Content-Type: multipart/signed; protocol="application/pkcs7-signature"; micalg=sha-256; boundary="------------ms050800020700090709000201" Return-path: Received: from mout02.posteo.de ([185.67.36.66]:59711 "EHLO mout02.posteo.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751225AbcJFTtC (ORCPT ); Thu, 6 Oct 2016 15:49:02 -0400 Received: from submission (posteo.de [89.146.220.130]) by mout02.posteo.de (Postfix) with ESMTPS id 469C820914 for ; Thu, 6 Oct 2016 21:48:56 +0200 (CEST) In-Reply-To: Sender: linux-can-owner@vger.kernel.org List-ID: To: Bremer Henning , linux-can@vger.kernel.org This is a cryptographically signed message in MIME format. --------------ms050800020700090709000201 Content-Type: text/plain; charset=iso-8859-15 Content-Transfer-Encoding: quoted-printable > I am using SocketCAN on a Beaglebone Black with Debian (Wheezy). I > have my Beaglebone plugged in a CAN-Network of 5 microcontrollers. Now > I would like to measure the time one message needs to be delivered > from my beaglebone to another microcontroller via CAN depending on the > priority (ID) of the sent message. > Is there a way to do this in SocketCAN? > IMHO latency is best to be measured with an oscilloscope or a logic analyzer. Switching a GPIO PIN is a good trigger to start a measurement. Just wait for the message to be sent and measure the time in between. As CAN is CSMA, latency has to be measured without other nodes on the network. The other option on the BBB is to sent a message from can0 to can1 and clock the time in between tx and rx. Assuming rx takes as much time as tx, you can split that time in half to get the latency. 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