From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Jander Subject: Re: MCP2515 implementation is slow Date: Thu, 27 Nov 2014 08:46:27 +0100 Message-ID: <20141127084627.6888dc6b@archvile> References: <84a1d29551f84f5494b309e1ad1e0840@SGPMBX1004.APAC.bosch.com> <5474B2BD.1030901@eurekelettronica.it> <2E9F00CBB66AB544A1ACDC59627518BA4F02C96C@mailserver> <20141126123242.13254.31551@shannon> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Return-path: Received: from protonic.xs4all.nl ([83.163.252.89]:26840 "EHLO protonic.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751231AbaK0Hq0 (ORCPT ); Thu, 27 Nov 2014 02:46:26 -0500 In-Reply-To: <20141126123242.13254.31551@shannon> Sender: linux-can-owner@vger.kernel.org List-ID: To: Andri Yngvason Cc: "linux-can@vger.kernel.org" , "Rost, Martin" On Wed, 26 Nov 2014 12:32:42 +0000 Andri Yngvason wrote: > Quoting Rost, Martin (2014-11-26 12:02:13) > > Hi all, > > > > > this VERY POOR chip. > > As the mcp251x is voted down by the list members regularly, is there an > > alternative you guys would recommend? > > > Well, sja1000 is pretty solid. They're used for example in the peak_pci. It is actually pretty sad that one still tends to mention this old dinosaur. It has a terribly slow parallel multiplexed bus-interface that works on 5V. If you want to connect it to a modern ARM SoC, you will have to implement some quite expensive level-shifting and then probably bit-bang the interface via GPIO's or use an (even more expensive and complicated) CPLD or FPGA to do the bus-translation. You are kidding, right? To go back to the sad reality of CAN interfaces: No, there seems to be no good alternative whatsoever. If you want SocketCAN on an embedded system, choose a SoC that has built-in CAN controllers or connect a supported commercial CAN interface via USB or (if you have it) PCIe. Please note that many commercial (USB-) CAN-interfaces are not capable of producing 100% bus load at higher bitrates. USB has too much latency and the dongles tend to have too little buffer-space (there's often a SJA1000 crammed up inside). Best regards, -- David Jander Protonic Holland.