I'm attempting to bring up a custom board for the iMX6ul based on the EVK and it seems like the SD card lines are not the same as the EVK. I'm wondering if it is possible to change which pins the boot uSD card is connected to. For example, could we use the alternate functions for one of the GPIOs as the Data line or is the pin-muxing fixed in the boot ROM?
Hi danielbujak,
you can just stop in U-boot and edit mmcroot variable to match the sd number you want to use.
Best regards,
Carlos
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Hi Carlos,
I'm actually stuck before that as I am unable to load u-boot at all.
The pinout for the SD card on the custom board vs the EVK is as follows:
Signal | EVK pin | Custom Board pin |
SD2_nRST | B4 | -- |
SD2_CLK | D8 | D8 |
SD2_CMD | C8 | C8 |
SD2_DATA0 | D7 | D7 |
SD2_DATA1 | B7 | E3 |
SD2_DATA2 | A7 | A7 |
SD2_DATA3 | D6 | D6 |
Regards,
Daniel
Please check following post.
Best regards,
Carlos
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Hi Carlos,
It seems like all this assumes that the device is able to locate the SD card. However, I'm not understanding how the device knows where the SD card is to find uBoot in the first place.
Regards,
Daniel
Hi Daniel,
The Boot ROM uses the state of BOOT_MODE and eFUSEs to determine the boot device. For development purposes, eFUSEs used to determine the boot device may be overridden by using GPIO pin inputs.
You can find this information in chapter 8 of Reference Manual.
http://www.nxp.com/docs/en/reference-manual/IMX6ULRM.pdf
Best regards,
Carlos
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