From mboxrd@z Thu Jan 1 00:00:00 1970 From: Wolfgang Grandegger Subject: Re: read() question from newbie Date: Thu, 19 Apr 2012 10:39:51 +0200 Message-ID: <4F8FCF57.70900@grandegger.com> References: <4F51DEF0.9060501@hartkopp.net> <4F553BDA.8060106@hartkopp.net> <4F553CA5.8080704@hartkopp.net> <4F56701E.3020104@hartkopp.net> <4F8D08D2.3090701@hartkopp.net> <4F8F24F0.5000501@grandegger.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from ngcobalt02.manitu.net ([217.11.48.102]:33539 "EHLO ngcobalt02.manitu.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753227Ab2DSIjz (ORCPT ); Thu, 19 Apr 2012 04:39:55 -0400 In-Reply-To: Sender: linux-can-owner@vger.kernel.org List-ID: To: Michael Economides Cc: Oliver Hartkopp , linux-can@vger.kernel.org On 04/19/2012 01:10 AM, Michael Economides wrote: > Hi Wolfgang, > > I checked and the Freescale BSP I'm using is based on Linux version > 2.6.24.7-rt21 Do you need rt? Anyway, IIRC, the MPC5121EADS board is supported by the mainline kernel: http://lxr.linux.no/#linux+v3.3.2/arch/powerpc/boot/dts/mpc5121ads.dts There is no need to use the old kernel from Freescale's LTIB distribution, which uses a special and old Socket-CAN implementation. Wolfgang. > On Wed, Apr 18, 2012 at 1:32 PM, Wolfgang Grandegger wrote: >> Hi Michael, >> >> On 04/18/2012 10:13 PM, Michael Economides wrote: >>> Hi Oliver, >>> >>> Looking on my scope, it does seem like the baudrate is a little off. >>> >>> Here are the commands I use to set up my CAN interface on my Linux board: >>> >>> insmod -m candev; >> >> Oops, you are using a very very old version of insmod. Are you using >> Linux 2.4.x? I do remember using "-m" with old Linux 2.4 distributions. >> >>> insmod -m mscan-mpc52xx; >>> insmod -m can; >>> insmod -m can-raw >>> ifconfig can0 up; >>> >>> ./cantest can0 baud 1000000; >>> >>> This "cantest" program uses: >>> >>> ifr.ifr_ifru.ifru_ivalue = baudrate; >>> ret = ioctl(s, SIOCSCANBAUDRATE, &ifr); >>> >>> to set the baudrate. But it seems from reading other discussions, >>> that this is not the correct way to set baud rate. >> >> That's right, in case you are using a recent kernel version. >> >>> I am using the MPC5121 from Freescale, in case that is relevant. >> >> What Linux kernel version do you use? Where did you get the drivers >> above from? >> >> Wolfgang. >> >>> On Mon, Apr 16, 2012 at 11:08 PM, Oliver Hartkopp >>> wrote: >>>> On 17.04.2012 06:16, Michael Economides wrote: >>>> >>>> >>>>>> >>>>>> I assume there is a CAN bus problem: >>>>>> >>>>>> - wiring (CAN_L/CAN_H) >>>>>> - correct CAN termination (2x 120 Ohms) >>>>>> - different bitrate >>>>>> >>>>> >>>>> I think you are right, but I have checked that, it looks ok. I will >>>>> check again. >>>>> >>>>> I am using a PCAN USB adapter, and the PCAN software says there is an >>>>> "acknowledge error" when it sends a frame to my Linux board. >>>> >>>> >>>> This is an indication for a missing counterpart CAN node: >>>> >>>> - Wrong connection wiring >>>> - Wrong termination >>>> - Wrong bitrate >>>> >>>>> >>>>> When the Linux board tries to send a frame to PCAN, the PCAN software >>>>> says "form error acknowledge delimiter". >>>>> >>>>> It seems this is the same error in both cases, just worded differently. >>>> >>>> >>>> Yes. But this means the same regarding the obvious problems. >>>> >>>>> >>>>> In your opinion, is this most likely a hardware issue? Or is there >>>>> still some way I could be doing something wrong at the software level? >>>> >>>> >>>> Did you swap CAN_H / CAN_L ?? >>>> >>>> It's definitely one of the three points above. No SW problem ... >>>> >>>> Try to add a third CAN node - if you have one. >>>> >>>> Regards, >>>> Oliver >>> -- >>> To unsubscribe from this list: send the line "unsubscribe linux-can" in >>> the body of a message to majordomo@vger.kernel.org >>> More majordomo info at http://vger.kernel.org/majordomo-info.html >>> >>> >> > >