From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ned Forrester Subject: Re: PXA270 SPI + SD card Date: Wed, 04 Nov 2009 18:27:14 -0500 Message-ID: <4AF20DD2.2050101@whoi.edu> References: Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: Cliff Brake Return-path: In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: spi-devel-general-bounces-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org List-Id: linux-spi.vger.kernel.org On 11/04/2009 04:54 PM, Cliff Brake wrote: > On Wed, Nov 4, 2009 at 4:53 PM, Cliff Brake wrote: >> Hello, >> >> I'm trying to get a PXA270 to talk to a SD card via SPI. Has anyone >> else done this? I haven't used an SD card, but... >> One of the requirements is the CS stay low for the entire transaction. >> Can this be done with the PXA270 controlling the frame (CS) signal, >> or is GPIO control typically required? A GPIO is typically used. The PXA2xx processors lack a multi-chip-select function for SPI devices, so one has to use a GPIO if more than one device is on the bus. Back in 2.6.20, there was a cs_control() call back to allow the pxa2xx_spi.c driver to control a separately allocated GPIO line. I think there is now a more generalized procedure in the kernel to specify the GPIO that is to be used for each device on the bus. > Also, what SPI mode is typically used for SD? Looks like 0 and 3 are > the closest (http://elm-chan.org/docs/spi_e.html). Not sure on that one. I think there was a lot of discussion about that a couple of years ago when someone was getting SD cards to work. You might want to search the archives if no one answers you directly. -- Ned Forrester nforrester-/d+BM93fTQY@public.gmane.org Oceanographic Systems Lab 508-289-2226 Applied Ocean Physics and Engineering Dept. Woods Hole Oceanographic Institution Woods Hole, MA 02543, USA http://www.whoi.edu/ http://www.whoi.edu/sbl/liteSite.do?litesiteid=7212 http://www.whoi.edu/hpb/Site.do?id=1532 http://www.whoi.edu/page.do?pid=10079 ------------------------------------------------------------------------------ Let Crystal Reports handle the reporting - Free Crystal Reports 2008 30-Day trial. Simplify your report design, integration and deployment - and focus on what you do best, core application coding. Discover what's new with Crystal Reports now. http://p.sf.net/sfu/bobj-july