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i.MX6UL fuse prog for eMMC boot failed

Question asked by Andreas Wiesinger on Aug 2, 2017
Latest reply on Aug 4, 2017 by Yuri Muhin
Branched to a new discussion


I tried to set the fuses of an i.MX6UL so, that it boots from eMMC.
Thus, I have worked out these bits for BOOT_CFG[1-4] according to the i.MX6UL Reference Manual:

01101101 11001000 (00000000) 00000000 = 0x6dc80000


I have burnt these bits in U-BOOT using the following line:

fuse prog 0 5 0x6dc80000

As far as I know, the processor also needs bank 0 word 6: BT_FUSE_SEL set to 1, to boot according to the fuse settings?

Thus I also performed:

fuse prog 0 6 0x00000010


The thing now is, that I broke the board. I cannot boot anymore.


I would like to know if I have done everything right, especially calculating the bits 0x6dc80000 and 0x00000010 ?

Thanks in Advance!

The BOOT_CFG bits I wanted to set are following (see UL Reference p. 208: Table 5-6. MMC/eMMC Boot Fusemap):

BOOT_CFG1[7,6,5] to select eMMC. 
BOOT_CFG1[3] to set normal mmc speed.

BOOT_CFG1[2] (Disable fast boot acknowledge, as we did not enable fast boot)
BOOT_CFG1[1]: 0 => no power cycle.

BOOT_CFG1[0]: 1: Loopback Clk Src: direct.


BOOT_CFG2[7,6,5]: 110  ... 8 bit DDR. 

BOOT_CFG2[4,3]:    01    ... eSDHC2

BOOT_CFG2[2]:       0      ... 400MHz

BOOT_CFG2[1]:       0      ... 3.3V SD Voltage.

Rest is 0. (CFG3 is reserved and CFG4 is all 0)