I posted this previously and it was confirmed from nxp that for eFuses to work, we must have the default SD2 pins assigned to the SD slot to boot from SD 2 with eFuses. : https://community.nxp.com/t5/i-MX-Processors/I-MX6ULZ-eFuse-boot-from-SD-with-custom-pinmux-for-SD-s...
However, now we are attempting to make the changes on our board and are having a difficult time understanding which actually the default SD2 slot pins are.
So as an example lets take SD2_CLK signal. Based on the RM the USDHC2 CLK can be routed to SD2_CLK, GPIO3_IO24, and NAND_RE_B pins/pads. But ALT1 mode is for only SD2_CLK and NAND_RE_B. We used SD2_CLK as this seems like the default SD2 clock pin. However, on the 6ull EVK they are actually using the NAND_RE_B for SD2_CLK and similarly the rest of the SD2 signals are also different and related to NAND instead of SD2 (e.g NAND_WE_B instead of SD2_CMD).
We blew the eFuses and the fuse values were read correct afterwards but could not boot to u-boot or OS. We can boot the OS fine via Serial downloader mode so all other operations are verified to work. Fuse values set and read below.
fuse prog 0 6 0x10
fuse prog 0 5 0x2840
So, ultimately our question is, which are the default pins for the SD2 signals that the ROM code looks in order to boot? the SD2_XXX or NAND_XXXX? If it is NAND_XXX, why is it that one? Or does it look at both?
The reference manual table :
And our schematics for SD2 slot is as follows:
Reference design Schematic snippet from the EVK schematic file.
Solved! Go to Solution.
Follow up question regarding this. Currently we have CLK, CMD, Data00 - 03 lines connected for SD.
We are rerouting it now as follows :
Signal Pin Pad
USDCH2_CLK NAND_RE_B D8
USDCH2_CMD NAND_WE_B C8
USDCH2_DATA0 NAND_DATA00 D7
USDCH2_DATA1 NAND_DATA01 B7
USDCH2_DATA2 NAND_DATA02 A7
USDCH2_DATA3 NAND_DATA03 D6
Will this be enough for the ROM to boot from our SD2 slot or do we need to connect other sd2 related signals that we do not use at the moment such as these below?