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To: Ricardo Ribalda Delgado <ricardo.ribalda@uam.es>
From: Wolfgang Denk <wd@denx.de>
Subject: Re: SD card over (xilinx_)SPI, timeout error while CID
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Date: Thu, 11 Jun 2009 23:07:51 +0200
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Cc: jan.nikitenko@gmail.com, Lorenz Kolb <lorenz@missinglinkelectronics.com>,
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Dear Ricardo Ribalda Delgado,

In message <aa76a2be0906111349s2ff947eo35149ef14e29d05a@mail.gmail.com> you wrote:
> 
> > What frequency does Your SPI-Bus use?
> 
> 33Mhz.... arghh. just checked is over the standard...  Tomorrow I will
> test with a slower clk

Just some really stupid questions:

This is with a 4xx core, right? Is this the same SPI controller design
like in AMCC's 40x and 44x cores, i. e. with a "FIFO" of depth 1?

Assuming you're running your SPI clock at 1 MHz,  you  get  one  data
byte  and  thus  one interrupt at a rate of 125 kHz. I doubt your CPU
can handle such a load?


Best regards,

Wolfgang Denk

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