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Second SD/SDIO card with Zedboard/Zybo


We've gotten the second SD controller working on Zedboard and Zybo, using PMOD SD connected via either the MIO PMOD E connector or EMIO and one of the other PMOD connectors. We've tested it with SD cards and with an Atheros WiFi card.


There are a number of changes to make in order to get it working.


1) Configure MIO to connect the second controller to the MIO pins. Or Configure MIO so that the second controller is connected to none of the MIO pins so that it can be connected via EMIO and programmable logic.


We did this in clearreg.c, which is run by our FSBL before it jumps to the entry point of zImage.



2) If attaching the SD card slot to MIO, use fly wires to swizzle the signals onto the right pins. 


If using EMIO, add the connection of the appropriate pins to the SD controller in the programmable logic.


3) The controller cannot run at full speed with fly wires or our EMIO logic, so added code to reduce the clock frequency used by the controller.


4) We program the logic after booting Linux, so we added a second SD devuce driver that we could load as a module after we programmed the logic. It reads the configuration from DTS just like the xilinx one.



It would be nice to have a PMOD SD whose pinout matches Zedboard and Zybo so that MIO could be used without fly wires. It would be much tidier and would run faster.

Edited by Josh
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Actually I found the JF pmode connector pins connected with SD Pins in MIO,So is there any possibility to add one more SD CARD in zybo with the help of JF Pmod connector ,And I tried onece but I got FR_NOT_READY and FR_NOT_EANABLED ,My hardware side circuit was perfect,can you please let me know your idea how to fix this problem.. 

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