Suggestion if possible about mmcblknx HOT 10 OPEN

I have not tried it myself, and I would not recommend it, because it uses different voltages on the communication levels (3.3V instead of 1.8V)

Stock linux driver is using the eMMC card in high voltage mode,
as per Jedec Embedded Multi-Media Card (e•MMC) Electrical Standard (5.1)

You would have to compile the linux driver with RTSX_LDO_VCC_1V8 instead of RTSX_LDO_VCC_3V3

Let me know if you will try this further,
Ignas

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The problem is that the Nvidia Tegra CPU is 1.8V logic level, and even cutting the power to the eMMC, would still expose the Tegra IO to 3.3V logic from the reader. The eMMC supports both 1.8V and 3.3V, but the Tegra does not.

One dirty solution would be to use Exploitee.rs Low Voltage eMMC Adapter, it has a TI TXS02612 level shifter and would shift the voltage levels to 1.8V.

But you would still need to breakout the wires from mmcblkNX.
During development I actually did that, but a microscope is really necessary.

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I have never had a Switch Lite, so I am just guessing.
Connect three wires DAT0, CLK and CMD over the level shifter to the pads. For SD_BUS_WIDTH_1BIT, you only need three.
And of course power. You may need to cut a trace to the eMMC if the CPU share the same 1.8V/3.3V rail.
Or put the Switch in RCM mode, if that is possible on the Lite.

Open the hardware/mmcblkNX.kicad_pcb with KiCad and you will see the net names on the tracks for reference.

Good luck and keep me posted

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Hi Ignas, does this mean that the mmcblkNX board can operate in 1-Bit mode? I'm trying to troubleshoot a exploitee.rs Low Voltage Adapter where I can read the Switch eMMC board just fine with the mmcblkNX but nothing with the exploitee. If it does, I could use it instead of the exploitee/Transcend TS-RDF5K combo. I've tried both a working Switch eMMC module and a SD card and neither work with the exploitee, so I thought if it works with the mmcblkNX then I could at least narrow it down to the other two.

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Wouldn't it be possible to change the PCB with a voltage divider to shift down the voltages? Maybe with a jumper that bypasses the voltage divider when working on a regular switch. I mean I'm willing to make these changes myself, I just don't know exactly which lines need to be shifted down.

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Hi, I will try to go this way to recover a switch lite. I first need to put my hands on an Low Voltage eMMC Adapter though...

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I am a little bit disappointed about the absence of 1 bit mode. I don't think it is supported on the Realtek chip.
I have just tried to wire up an emmc over 1 bit mode.

Can anyone else confirm this behaviour?

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Did you get anywhere with this @bormay ?

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