The SD card is not displayed, what's the problem?

Question

linux

Good day to all.
Linux for Orange Pi microcomputer is installed on the microSD memory card, I inserted this microSD card into the phone, but the phone and the computer do not see this microSD memory card, what could be the problem?
Thanks in advance!

Answer 1

See WinHEX program, or Linux operating system. The phone considers this card a regular one - where there is only 1 section. And there, in fact, at the beginning there is no marked area at all - not according to the standard in general, therefore they don’t see it because at the beginning the loader is instead of the partition table.

Answer 2

The fact is that there is a file system on the card that the computer OS cannot see, like the phone (although, in theory, androids should see ext3, but I could be wrong)

Answer 3

On the card you have the ext file system, which just should not be visible, at least in Windows. About Android - it is necessary to specify in addition.
To access the memory card, you will need additional software, such as the popular Ext2Fsd (file system driver). I also met mentions that under Windows 10, installing WSL (aka Microsoft Bash) gives access to the ext file system.
With Android, you can also try to insert the card into the card reader and connect it via OTG.
Separately, I note that I did not test the methods above myself, because. there was no such need, so I will not judge which is better.
Microcomputers can also lay out the map in a non-standard way. If I'm not mistaken, for example, the Raspberry Pi has one small (10-15 MB) partition visible, the rest are not.
If you need infrequent or one-time read access, or don't want to install software, you can use R.saver . It's free, you don't need to install it, and it allows you to read data from a bunch of different file systems if they are not damaged.