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I would like to connect SPI IP core of microblaze on custom board but I have some problem. I need 100-400 KHZ clock but the system clk is 100MHz and SPI Clock is 6.25 MHz. Is it necessary to reduce clk frequency for initialization?

I just send CMD0 to reset,I would like to check the write and read buffer to see tranfering of command is correct,but I couldn't get a correct result.

IS anybody can help me ?

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Is it necessary to reduce clk frequency for initialization?

Yes. SD cards come up in open drain mode - you also need a pullup. This resistor limits the answer speed of the card until it switches into SPI mode fully.

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  • \$\begingroup\$ How I can reduce the clk frequency? \$\endgroup\$ – Student77 Jul 5 '16 at 13:05
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    \$\begingroup\$ Use a Clock divider maybe...? \$\endgroup\$ – Turbo J Jul 5 '16 at 14:03
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I did not use microblaze, but the idea is that you should be able to intialize/set up parameters of your SPI block. This will generate your output clock. Otherwise, you need to provide a desired clock to the SPI block. If microblaze dos not generate output clock, you can create one using Clock wizard block.

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