i.MX8M Mini EVK SD Card Detect pin

[fernando_lopes]

Hi,

I am designing a custom board with i.MX8M Mini and it will need to boot from an SD-Card.

The EVK uses the SD2 interface for SD. But on the EVK, the "Card Detect" signal is connected to the pin GPIO1_IO15 instead of the pin SD2_CD_B and I could not understand why. So I have the following questions:

1. Why isn't it connected to the SD2_CD_B pin? 

2. Can I use the SD2_CD_B pin for "Card Detect" signal on my design?

3. Does the boot ROM need the CD signal?

Thanks.

[inderjitbains]

If booting from SD2 with a new CPU, does the CPU look at SD2_CD_B or GPIO1_IO15 to detect if a card is present, or does it ignore card detect?

[igorpadykov]

Hi Fernando

for card detection options one can check sect.3.3.6 Device Tree Binding

attached Linux Manual. Seems gpios are used for routing convenience.

Best regards
igor
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[fernando_lopes]

Thank you Igor.

I think the GPIO is not used for routing convenience because there are 2 resistors to choose to which i.MX pin the CD pin from SD connector is connected. There are options for using the GPIO1_IO15 and the SD2_CD_B pin, but for some reason the GPIO is chosen by default.

Do you know if there is any problem with the SD2_CD_B pin?

[igorpadykov]

there are no problems with the SD2_CD_B pin.

Best regards
igor