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1  Using Arduino / Storage / Re: Using arduino to recover data from corrupt sd card on: September 25, 2012, 11:02:55 am
Thank you for the advice, but if it was such a simple software problem (e.g accidental write in some critical sectors such as the partition table) my problem would be solved by now. I regularly use photorec and the like to recover data for friends and family.
Long story short, I know the card suddenly stopped working but I only noticed it when I tried to put it back in my camera. It said «card error» and I was immediately like «uh-oh».
I put the card in my computer and looked at hexdump -C and saw «MSDOS 5.0» somewhere at the beginning. At that point I was pretty confident that it was a minor problem since the partition tables seemed to be still there — in part at least. I immediately launched a copy with dd, only to find hours later that the data I copied was completely garbled, with no trace of the first sectors I saw previously.

A closer examination through different card readers lead me to think that something is really fried in the card (slightly different output depending on the readers, the card seems to output the same block repeatedly, and dmesg reports an error about a missing function in the card).

I know it is possible to desolder the nand chip to read it raw with specialized hardware and software, but before doing this I thougt that maybe using SPI mode wold go through different circuitry and work around the problem.
2  Using Arduino / Storage / Using arduino to recover data from corrupt sd card on: September 24, 2012, 05:41:46 pm

I got a sdhc 32G sd-card on which were my last holiday pictures.

We just looked at them on my friend’s computer, and now it seems there’s only rubbish on the card.
I suspect it comes from the card, not a virus.

Do you think it is worth trying to read the card in spi mode instead of the internal reader of a computer (sdio mode, I guess) ?
maybe the data is still here...

Thanks for your advice.
3  Using Arduino / Networking, Protocols, and Devices / Re: Point to point wired communication between 2 arduinos on: August 01, 2011, 02:00:28 am
Thanks, i believe this is simple enough. But What about the insulation ? Isn’t it dangerous to connect the two grounds of different (switch-mode) power supplies ?
4  Using Arduino / Networking, Protocols, and Devices / Point to point wired communication between 2 arduinos on: July 31, 2011, 06:16:22 pm

I'd like my 2 arduinos to chat a little, and I'm looking for a solution as cheap as possible. Everybody seems to focus on wireless, so I didn't find any interesting stuff yet. Here is what I'm looking for :

The "network" should be as simple and cheap as possible (classic components, possibly scavenged from various sources esp. computer parts)
Max. 4 wires between the boards, if possible 2
Both boards will be able to talk when they need (peer-to-peer configuration)
The two boards have different power sources, so galvanic insulation will be needed I think

I tried to send a signal (on/off) on a pin through a self-made transformer (wound thin wire around a stud) but the other side didn't pick up anything. I fear my electronics skills are limited...

Ideas ?
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