From mboxrd@z Thu Jan 1 00:00:00 1970 From: Kenneth Heitke Subject: Re: ADS1256 - too fast for Linux ? Date: Fri, 14 Jan 2011 16:29:42 -0700 Message-ID: <4D30DC66.6080706@codeaurora.org> References: Mime-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Cc: spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org To: =?ISO-8859-1?Q?Fl=E1vio_Alberto_Lopes_Soares?= 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 01/14/2011 05:02 AM, Fl=E1vio Alberto Lopes Soares wrote: > Hello all, > I need to communicate with a Texas Instruments ADS1256 SPI 24 bits ADC ( > http://focus.ti.com/docs/prod/folders/print/ads1256.html) from a 2.6.32 > kernel Linux running on a ARM Samsung S3C2440 microcontroller using spidev > module, to do this I need to pass a command on MOSI channel and after read > the result on MISO, but I can't read the correct data from this ADC, the > data is always corrupted, I believe (but I can't prove this) this occurs > because the very short time between the command and response, according w= ith > the component datasheet this time is 50x the clock period, for my circuit > this is approximately 8us and I believe that there's no time to Linux get > the interrupt from SPI process this and read the SPI data, my suspicion c= an > be correct ? The DMA cannot solve this problem and if true how to know if= it > is activated ? Only Real Time Linux can solve this ? > > Thanks for all help > > Flavio Alberto Lopes Soares > -------------------------------------------------------------------------= ----- > Protect Your Site and Customers from Malware Attacks > Learn about various malware tactics and how to avoid them. Understand > malware threats, the impact they can have on your business, and how you > can protect your company and customers by using code signing. > http://p.sf.net/sfu/oracle-sfdevnl > _______________________________________________ > spi-devel-general mailing list > spi-devel-general-5NWGOfrQmneRv+LV9MX5uipxlwaOVQ5f@public.gmane.org > https://lists.sourceforge.net/lists/listinfo/spi-devel-general > Curious if the SPI mode (clock polarity and phase) are set correctly for = the device that you are communicating with. Ken -- = Sent by an employee of the Qualcomm Innovation Center, Inc. The Qualcomm Innovation Center, Inc. is a member of the Code Aurora Forum. ---------------------------------------------------------------------------= --- Protect Your Site and Customers from Malware Attacks Learn about various malware tactics and how to avoid them. Understand = malware threats, the impact they can have on your business, and how you = can protect your company and customers by using code signing. http://p.sf.net/sfu/oracle-sfdevnl