Seems to be a common problem with Sandisk micro sd cards.

Just a little before or after the warrenty period, the micro sd card suddently stop to be recognized. I mean phones and external card reader complains no sd card is inserted at all when put inside them (nothing is detected).

Of course, before going to find a logic analyser maybe some ata commands which can be launched from a computer might be useful (but I don t know which ones).

  • \$\begingroup\$ Even if you could figure out what was happening, how would you expect to fix it? \$\endgroup\$ – Ron Beyer Dec 23 '19 at 16:13
  • \$\begingroup\$ Is this academic? I don't understand what you will do with this knowledge. Buying a silicon fab is likely to cost more than a new sdcard. \$\endgroup\$ – foreverska Dec 23 '19 at 16:17
  • \$\begingroup\$ @foreverska I put an ethereum private key on it. So it definitely worth a lot of more than a plain sd card or even a sport car. \$\endgroup\$ – user2284570 Dec 23 '19 at 19:22
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    \$\begingroup\$ Well then it may be worthwhile to look into a data recovery service that supports sdcards. Point is, if there is a failure, it's not an easy fix. A device such as an SD card doesn't suddenly decide to stop reading, it's a hardware failure. If the reader is known good and the card isn't reading, find a recovery service if it's truly worth that much. \$\endgroup\$ – foreverska Dec 23 '19 at 19:29
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    \$\begingroup\$ It's unlikely that your computer has suddenly started sending out incorrectly formatted commands, especially considering multiple readers/devices. The "card detect" is a hardware feature of the socket, not the card. I'm 99% sure you have a dead card. There is an enumeration process the card goes through, if it isn't responding to that on multiple devices, then the card is dead, it isn't unheard of. \$\endgroup\$ – Ron Beyer Dec 23 '19 at 20:09

Your card is likely dead beyond a protocol working. But since you insist on arguing that point here's a long shot:

SD Cards can be run on a publicly available SPI protocol. It's going to be slow but it does work. Here's a starting point:


The protocol can be written on a microcontroller in a solid 8 hours.

Good luck.

  • \$\begingroup\$ And isn t there a such reader for sale directly? Would doing it from Linux with a raspberry pi work? \$\endgroup\$ – user2284570 Dec 23 '19 at 20:48
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    \$\begingroup\$ If the data on the card is valuable, inexpert messing with it is unwise. \$\endgroup\$ – Chris Stratton Dec 23 '19 at 20:51
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    \$\begingroup\$ I don't think I've ever seen such a reader. Most google searches are just tutorials on how to do it yourself because it's really not an advanced protocol. Any device with SPI will work. \$\endgroup\$ – foreverska Dec 23 '19 at 20:51
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    \$\begingroup\$ Storing valuables on an SD card with no backup is unwise but here we are. Don't use any commands that write or erase, pay attention to wiring and voltage levels. Or yes, pay a professional, but that was already shot down in comments. \$\endgroup\$ – foreverska Dec 23 '19 at 20:56
  • \$\begingroup\$ For 256Gb I hadn t enough space elsewhere. Bought storage 2 weeks ago, but the sd card failed before it arrives in the box. If you know a professional in France then I m Ok. Otherwise, can I use spi mode through a raspberry pi? \$\endgroup\$ – user2284570 Dec 23 '19 at 22:27

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