From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bernd Krumboeck Subject: Re: Linux board with 10 CANs Date: Fri, 15 May 2015 15:54:51 +0200 Message-ID: <5555FAAB.4090306@universalnet.at> References: <5555A6A3.7090206@orange.fr> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Received: from smtp.xy24.at ([85.126.109.136]:34523 "EHLO renate.xy24.at" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1030335AbbEOOIY (ORCPT ); Fri, 15 May 2015 10:08:24 -0400 In-Reply-To: <5555A6A3.7090206@orange.fr> Sender: linux-can-owner@vger.kernel.org List-ID: To: =?UTF-8?B?RnJhbsOnb2lzIEJlYXVsaWVy?= , linux-can@vger.kernel.org Hi! I don't know much about this things, but what do you think about follow= ing: Use two 4 port usb hub (MICROCHIP USB4624I-1080HN) with 8 x STM32F072 o= r STR750FV2. You can flash the MCUs under linux with dfu-util (http://dfu-util.sourc= eforge.net/). A firmware for STR750FV2 is available here (please check license): https://github.com/krumboeck/usb2can_firmware I don't know if it works, but there is also a gcc version available: https://github.com/krumboeck/usb2can_firmware/tree/gcc-test If you use this firmware or at least the same procotol, then the hardware will be compatible with usb_8dev can driver. regards, Bernd Am 2015-05-15 um 09:56 schrieb Fran=C3=A7ois Beaulier: > Hi, > > I'm starting the design of a CPU board, based on a computer on module= with a very common SOC like i.mx6 or am335x. > I need to fit my board with at least 10 CAN ports, may be more. (The = SOC have 2 CANs so i need 8 more) > The board will run with Linux and of course i want a socketcan interf= ace for each bus ! > CAN bitrate needed is quite low (50kbps) and latency is not critical = but bus load may reach 100% sometimes. > As far as possible i want to avoid driver development, or just doing = slight modifications on an existing driver. > I don't want to use MCP2515, i had trouble with it on a previous desi= gn because of the lack of buffer in the chip. > I can't imagine putting 8 MCP2515 and not missing any frame, but may = be i'm wrong ? > > Here are the options i have considered, they involve using external M= CUs to provide enough CAN interfaces : > > - MCUs with SLCAN : SLCAN have the advantage of simplicity and it sho= uld offer enough performance at low data rate. Problem is that it would= require 8 UARTS. I could modify SLCAN driver to allow multiple CAN cha= nnels on the same UART, and so use MCUs with multiple CANs, does it sou= nds reasonable ? > > - MCUs with SPI 1 : adapt MCP2515 driver in a way to make the SPI pro= tocol manageable on the MCU side (SPI slave). The MCU will be able to p= rovide the buffer for CAN frames that the MCP does not have. This optio= n is just a way of trying to go fast, it is not very elegant, and have = the limitation of one CAN channel per SPI connection / driver instance. > > - MCUs with SPI 2 : use the Stefano Babic SPI driver posted on this l= ist. This is probably the best choice for a long term and more generic = solution. But i'm afraid it may require too much work to complete. What= is the status of this driver right now ? Does anyone have an idea of t= he remaining work to do to make it ready for mainline ? Stefano are you= available to spend more time on it ? I'm also wondering whether multip= le instances of the driver can run concurently if i put more than one M= CU ? > > Concerning the MCU software i could release it as an open-source proj= ect, anyone interested in participating ? > I'm very familiar with STM32 MCUs so i will probably use an STM32F072= (low cost cortex M0 with one CAN). > > Any idea or advice is welcome, thank you for reading this much too lo= ng post. > > Regards > > Francois Beaulier > www.ingelibre.fr > -- > 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