Colibri iMX6 microSD card compatibility

  • Device: Colibri iMX6DL 512MB IT V1.1A
  • Linux Kernel: 4.9.166-rt125-2.8.6

We previously used the following microSD cards, which performed well for us:

  • Panasonic RP-SMLF64-DA1

However, these cards are no longer manufactured, and we’re facing challenges finding compatible replacements. We’ve tested the following models, but none of them seem to work. The system doesn’t detect them—they appear as if they don’t exist:

  • Swissbit SFSD064GN1AM1TO-I-6F-221-STD

I wonder what could be the potential causes of this issue? Could it be related to the flash type (e.g., MLC/TLC), the SD Memory Card Specification, or the bus speed/interface?

Any insights would be appreciated!

In our hardware design, the SD card CLK/CMD/DAT0/1/2/3 signals are pulled up to 3.3V using 10K resistors.

If we remove the pull-up resisters, will iMX6 work at 1.8V UHS-I bus? Could this fix the issue?

Yes, it could fix the issue. According to the Colibri iMX6 datasheet:

The Colibri iMX6 supports UHS-I which allows up to 104 Mbyte/s transfer speed on its standard SD
card interface. However, UHS-I requires 1.8V IO level, which is not in the Colibri module
specification. Since the 1.8V capability is not mandatory in the Colibri module specification, other
modules may support only 3.3V logic level. Pay attention to the SD card signal pull-up resistors on
the carrier board. If the interface is used in the 1.8V mode, it is recommended to remove the
pullup resistors on the carrier board. The iMX6 features internal pull-up resistors, which can be
used instead.