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SD card interface requires 1.8V or 3.3V signaling depending on the usage mode as shown below.
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I.MX8MP Platform
I.MX8MP platform provides a control bit (VSELECT) on a memory-mapped register VEND_SPEC to select the required voltage.
The value of the output signal VSELECT from the controller can be configured by changing the value in the register and there must be a control circuit out of SDHC controller to change the voltage on pads.