How to use Arduino to switch between microsd cards?

Question

Arduino

Actually the subject in the next you need to switch between cards of the format such as microsd. There is a pool of flash drives connected to slots and a regular card reader. Arduino should switch slots. The question is whether this is possible and what is needed for this (controllers for Arduino, etc..).
The picture shows schematically what needs to be done.

PS Do not kick it for the scheme, for a better perception of what you need to get.

Answer 1

Perhaps ... judging by the diagram of the picture, a friend wants to connect several slots with cards to one card reader ... and control the controller, switch between slots. In this case, the number of slots with cards = the number of free I / O of the Arduino controller. If I understood the task correctly, then it is enough to connect all the outputs from the card slots in parallel to the corresponding inputs of the reader cards, and using the outputs of the Arduino controller, simply apply Vdd to the slot you need. which will lead to its activation.

Answer 2

Look at the picture
: surely you will have flash drives via SPI, then pay attention to pin number 2 (CS). If you pull it to the ground, the flash drive will work with SPI, if not, it will not respond.
In order not to wind up a bunch of legs, put a decoder: say, a cascade of BCD 4-bit decoders will provide M = 2 ^ N (N is the width of the input address bus) outputs.
In total, you will need: 3 SPI legs for working with cards + log2 (M) legs for addressing.
I didn’t understand about the card reader: what is it for?

Answer 3

As I understand it, the author of this question has a bunch of extra cards and little memory in the phone or something like that :) microsd cards really dislike incorrect shutdown, that is, in any case, you need to "safely remove" the card before pulling the power, otherwise there will be constant data loss and flash drives will start very quickly. So the idea will most likely not work.