i.MX6 uSDHC4 UHS-I -> Voltage levels on NVCC_NANDF

[g_moreno]

Hello,

I want to use the uSDHC4 interface for an SD card connection. Taking into account that the uSDHC4 interface belongs to the NVCC_NANDF power domain and that I need to support UHS-I speed modes, it is necessary to place an external power switch to change the NVCC_NANDF node between 3.3V and 1.8V. This voltage change not only affects the uSDHC4 pins, but also all NANDF pins (which include several GPIOs)

My questions are:

1. If I want to use some of these GPIOs as outputs, is there a way to have 3.3V levels when NVCC_NANDF is at 1.8V (UHS-I)?

2. The SD4_VSELECT signal is located in the NAND_CS1_B pin. Does this mean that I have to select a power switch that is able to read a logic level "1" with 1.8V in the Enable input, when powered from 3.3V? Normal high voltage threshold levels are 0.75*VCC.

Thanks,

Guillermo Moreno

[igorpadykov · Accepted solution]

HI Guillermo

1. there is no way to have GPIO 3.3V levels (with NVCC_NANDF power domain)

when NVCC_NANDF is at 1.8V

2. I believe yes, (if NVCC_NANDF is powered with 1.8V)

Best regards

igor

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