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Internal non removable SD card switching with removable

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bestcallumuk

New Member
Is it possible to make a device that has an internal SD card that cannot be removed and an external one that can which when the external is plugged in it switches place with the internal. If you found that confusing I will try to rephrase it.

Thank you in advance.
 

Pommie

Well-Known Member
Most Helpful Member
Yes, just make the internal one impossible to remove and write your code appropriately.

Mike.
 

Sceadwian

Banned
SD cards can be run in parallel, with one exception, you need to run seperate wires for each chip select line. Then to select the chip you want to access you would trigger the appropriate chip select line.
 
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DirtyLude

Well-Known Member
You have to tell use how your interfacing with the SD card. Or are you asking about modifying something you already have?

If you are interfacing an SD card with a microcontroller, than Sceadwian's solution should be fairly obvious to implement. Many SD card slots will have card detect, which you can use to check when a card is inserted.
 

bestcallumuk

New Member
Could I make a switch that switches between 2 sd cards by making a switch that switches between the two SD card's power (pin 4 (Vdd))? So the switch switches power in to each SD card? (A switch the easy way out! Also I decided it would be better anyway)
 
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Sceadwian

Banned
bestcall, a solution has already been present, in SPI mode there is a chip select line that is used, it's entire purpose is to do what you want, so use it =) you'd just need a single DPST switch that's break before make.

As Dirtlude asked, how are you interfacing to your SD card? Because from what I've researched so far there are three modes. SPI mode, 1 bit SD mode, and 4 bit SD mode.
 
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mneary

New Member
Switching power doesn't solve the problem with chip selection. It would also require buffering the I/O so it doesn't load down the I/O of the active chip.
 
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