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Just wondering if it is possible to detect the presence of an SD card when it is being used in SPI Mode?

enter image description here

It would appear that the card detect/data 3 pin (CD/DAT3) is used as a chip select (CS) pin when in SPI mode.

If this is true, then how does one detect the presence of an SD card being used in SPI mode?

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    \$\begingroup\$ The "card presense" pin is usually a NC switched contact in the (micro)sd cards socket, and not on the card itself. \$\endgroup\$ – Turbo J Jan 6 '17 at 14:51
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Just realized that some microSD card holders have a "hidden and un-numbered" pin called "card detect" that gets shorted to ground when a card is inserted. See picture below

enter image description here

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The micro sd-card socket has more than 8 pins. At least 2 extra pins for write protection & insertion detect.

As shown in the below picture, the insertion detect pin is grounded through mechanical means when the SD card is inserted into the slot. enter image description here

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