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SD card low level read

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How could SD card be read if there isn't drive letter assigned to it and it doesn't show in Disk Management?

I can read cards that show in Disk Management with this:

--- Code: Pascal  [+][-]window.onload = function(){var x1 = document.getElementById("main_content_section"); if (x1) { var x = document.getElementsByClassName("geshi");for (var i = 0; i < x.length; i++) { x[i].style.maxHeight='none'; x[i].style.height = Math.min(x[i].clientHeight+15,306)+'px'; x[i].style.resize = "vertical";}};} ---hBlockDevice := CreateFile(PChar(sFileName), GENERIC_READ, FILE_SHARE_READ or FILE_SHARE_WRITE, nil, OPEN_EXISTING, 0, 0);// where sFileName is something like \\.\PHYSICALDRIVE1  if hBlockDevice <> INVALID_HANDLE_VALUE then   begin    SetFilePointer(hBlockDevice, BlockSize * dwSector, nil, FILE_BEGIN);    ReadFile(hBlockDevice, Buffer[0], BlockSize, dwRead, nil);    ...
But if card doesn't show in Disk Management I get INVALID_HANDLE_VALUE.

In the general case, forget it. BTDT, and the only way you can get low-level access to a possibly-damaged card is by using something like an Arduino.



There is a marvelous tool  simply called testdisk

Available for a lot of OS but I would advise Linux, because Windows gives up quick.

As long a Linux detects a device there is a good chance to recover your data.

Before you plug the card do a

ls /dev/sd*

Plug the card and do the same. If something changed then the new device is your card. Then there is  good chance to get the data back.

I recovered a lot of broken hard-disks with testdisk. For example:

*External 350 GB full of music but with a zerod  directory
*Laptop-Disk, which had a big scratch from a crash: 85% of the photos saved. The other 15% were on the cratch

Hope you are lucky!

Cards are not damaged. They are used in microcontroller operated devices and probably has some custom memory organization.
I hoped I could read them from Windows when some of this devices stop working.

I will try with Linux and if that doesn't work I'll try it with Arduino.


--- Quote from: winni on August 25, 2021, 09:08:48 pm ---There is a marvelous tool  simply called testdisk

--- End quote ---

Maybe it won't help me now with this SD cards, but thank you for tip on this tool. I just hope I won't need it anytime soon. :)


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