i.mx6ulz Default SD pins for eFuse Boot

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i.mx6ulz Default SD pins for eFuse Boot

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Angshu
Contributor III

Hi,

 

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 :

Angshu_0-1616692964094.png

 

And our schematics for SD2 slot is as follows:

 

Angshu_4-1616696451827.png

 

Reference design Schematic snippet from the EVK schematic file.

Angshu_3-1616696373607.png

 

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Angshu

 

default SD pins for boot are described in sect.8.5.3.4 IOMUX configuration for SD/MMC

i.MX 6ULZ Applications Processor Reference Manual

 

Best regards
igor

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igorpadykov
NXP TechSupport
NXP TechSupport

Hi Angshu

 

default SD pins for boot are described in sect.8.5.3.4 IOMUX configuration for SD/MMC

i.MX 6ULZ Applications Processor Reference Manual

 

Best regards
igor

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Angshu
Contributor III

Hi Igor,

 

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?

DATA4   NAND_DATA04
DATA5   NAND_DATA05
DATA6   NAND_DATA06
DATA7    NAND_DATA07
VSELECT  GPIO1_IO08
RESET_B   NAND_ALE

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igorpadykov
NXP TechSupport
NXP TechSupport

yes this is enough for ROM to boot from SD2.

 

Best regards
igor

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Angshu
Contributor III

Hi Igor,

Thank you for the answer. We just ran into that table after posting here. Much appreciated.

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