iMX8m mini

[Sadatan123]

I want to run a Wi-Fi+BT module on M.2 connector of iMX8M mini EVK on SDIO interface but SDIO interface on M.2 connector is not connected anywhere on base board.

Can I remove Sd card and connect the signals from SD2 (i.e. CMD, CLK and D0-D3 ) to SDIO signal's test points on M.2 connector and test the Wi-Fi+BT module the way given below:

Will there be any change needed to be done in Software or its integrated in Linux?

[Chavira]

Hi @Sadatan123!
Thank you for contacting NXP Support!

You have to use the imx8mm-evk-usd-wifi.dtb to use SDIO signals from the SD2 connector.

Best Regards!

Chavira

[Sadatan123]

What do you think I need to change in software or hardware if the module which I am connecting on SD2 of IMX8Mmini EVK has 1.8 V signals?

[Chavira]

Hi @Sadatan123!

The device tree imx8mm-evk-usd-wifi.dtb automatically adjust the voltage to 1.8v.

This device tree put a HIGH value on pin SD2_VSEL of the PMIC changing the NVCC_SD2 voltage from 3.3v to 1.8v.

[Sadatan123]

Hi Chavira,

Thanks for this information. We did the required changes by integrating imx8mm-evk-usd-wifi.dtb. This did change the voltage levels of SDIO interface to 1.8V, but during boot up for voltage remains 3.3V until device loads the Kernel. We tried interrupting boot sequence and keeping device in U boot and voltage remained 3.3 V but as soon as we load the kernel image it changes to 1.8V (desired voltage)

[Chavira]

Hi @Sadatan123!

Try modifying the u-boot device tree too.

in node usdhc2 add the line:

pinctrl-assert-gpios = <&gpio1 4 GPIO_ACTIVE_HIGH>;

and finishing add the next line to all pinctrl of usdhc2 :

MX8MM_IOMUXC_GPIO1_IO04_GPIO1_IO4	0x1d0

After those changed the voltage should be 1.8v too in u-boot stage;

[Sadatan123]

Hi Chavira,

Thanks for your quick reply.
Just wanted to check one thing, if I use SDIO interface SD2 (on which SD card in connected) on base board of imX8Mmini EVK to connect a wi-fi module. Do I need to make any changes on the base board or SOM to boot it from eMMC? Does this evk boot from eMMC or SD card by default?

[Chavira]

Hi @Sadatan123!

You have to boot from eMMC.

The Board boot according to the boot switches.

You can consult a detailed information in the IMX8MMEVK User Guide