AXI SPI of MicroBlaze connected to SD card

Question

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 ?

score 1 · Answer 1 · answered Jul 05 '16 at 12:47

1

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.

answered Jul 05 '16 at 12:47

Turbo J

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How I can reduce the clk frequency? – Student77 Jul 05 '16 at 13:05
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Use a Clock divider maybe...? – Turbo J Jul 05 '16 at 14:03

score 0 · Answer 2 · answered Oct 03 '16 at 15:54

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.

AXI SPI of MicroBlaze connected to SD card

2 Answers2