Interfacing Compact Flash with Spartan 3

Mar 11, 2005 3 Replies
G

Hello, In out project, we have to interface a Compact Flash card with a Spartan-3 fpga in Ultra-DMA mode. In the CF 3.0 specifications it states, that most of the lines need series termination resistors. We were just wondering, if those termination resistors are really needed, since the CF will be no more than an inch away from the Spartan 3. If they are indeed needed, we might have a problem determining the resistors values and doing signal integrity analisys, since we haven't been able to find an IBIS model for a CF card.



Best regards George



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T

needed,

haven't

I have not designed with CF, but I'd be more concerned about the Spartan 3's

3.3v tolerance. The oxide of that device breaks down at 4v and undershoot allowed is minimal as well, like .5v
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M

Are the series termination resistors needed in all modes of CF data transfer, or only in the faster modes?

It should be possible to use Vcc = 3.3V for the CF card.

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G

The specifications only mention line termination with UltraDMA-66 mode, which is the fastest. But it's not that fast, since It's "only"

66MBytes transfered on 16 Bit wide bus. Data is transfered on bost edges of strobe signal so the frequency is no greater then about 16MHz.
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