Help! need to refer someone for SDcard in dominican republic

[fzabkar]

The bit is not flipped -- it is stuck low, ie a "cold" bit. If the card is a 4-bit type, then this is not an interface error. OTOH, if it is an 8-bit type, then it could be an I/O fault, in which case the NAND would be OK. If it's not an I/O fault, then it could be either a controller or NAND fault.

If it is a NAND fault, there may still be a solution. If bit #6 is weak rather than stuck at 0V, then it may be possible to boost the signal with a comparator or op-amp. I have "repaired" several devices using such an approach. I can help with advice, if need be.

In any case, the problem cannot be solved by flipping bit #6 in the output.

[fzabkar]

AFAICT, only 1 bit in 32 is cold. Wouldn't that point to a fault in the controller?

Code:

0x45786966 = 0b  0100 0101  0111 1000  0110 1001  0110 0110  (Exif)
0x45786962 = 0b  0100 0101  0111 1000  0110 1001  0110 0010  (Exib)
                  ^    ^     ^    ^     ^    ^     ^    ^
                                                        bad

[ddrecovery]

AFAICT, only 1 bit in 32 is cold. Wouldn't that point to a fault in the controller?

Code:

0x45786966 = 0b  0100 0101  0111 1000  0110 1001  0110 0110  (Exif)
0x45786962 = 0b  0100 0101  0111 1000  0110 1001  0110 0010  (Exib)
                  ^    ^     ^    ^     ^    ^     ^    ^
                                                        bad

We are trying to diagnose an SD Card that the OP does not have in his possession, has been to a DR company previously, who may or may not have complete a chip off...... Just trying to diagnose the issues from some corrupt files is pretty difficult.

[fzabkar]

AFAICT, only 1 bit in 32 is cold. Wouldn't that point to a fault in the controller?

Code:

0x45786966 = 0b  0100 0101  0111 1000  0110 1001  0110 0110  (Exif)
0x45786962 = 0b  0100 0101  0111 1000  0110 1001  0110 0010  (Exib)
                  ^    ^     ^    ^     ^    ^     ^    ^
                                                        bad

We are trying to diagnose an SD Card that the OP does not have in his possession, has been to a DR company previously, who may or may not have complete a chip off...... Just trying to diagnose the issues from some corrupt files is pretty difficult.

I have years of experience chasing stuck bits in digital logic. You can infer a lot about the likely source of a fault if you understand the bus structure. If the NAND does not incorporate a 32-bit bus, then it is unlikely to be the culprit.

[fzabkar]

It can't be a bad NAND because a NAND with a stuck bit would produce uncorrectable ECC errors.

[Arch Stanton]

Hi fzakbar,

I greatly appreciate what you're doing, I really admire this type of bit-f*ckery and your answers often blow me away, you like a waking encyclopedia. But to be honest the input kind of causes an overflow. Maybe I should just have stopped with asking for someone who can do flash recovery close by to my customer. Me myself I don't do anything hardware related.

Do you need/ want an entire corrupted file? Is there anything I would be able to do to deal with a stook bit? I mean I will not be able to tell if a bit is 0 because it's stook or because it is supposed to be 0, right?

Basically, what would you suggest is what I'm trying to ask I guess.

[fzabkar]

One other possibility is that the card is OK, and that the files were corrupt before they were written to the card. If so, then the camera's RAM would be suspect, and there would be nothing one could do to recover the data.

In any case, there is no way to fix the damaged files.

[Arch Stanton]

OK. Yes, I considered that too, photos being saved corrupt. I don't suspect RAM. Photos with same camera I had customer take on a different card are okay.

[ddrecovery]

One other possibility is that the card is OK, and that the files were corrupt before they were written to the card. If so, then the camera's RAM would be suspect, and there would be nothing one could do to recover the data.

In any case, there is no way to fix the damaged files.

That is why I am saying there is no way to tell without the actual card.

@Arch Stanton: In the interests of R&D, if the client wants to send the card to me I will work with her on a price that fits her budget. Please PM me if interested.

[Arch Stanton]

ddrecovery thanks so much, but I think she just sent it to Jeremyb

[ddrecovery]

ddrecovery thanks so much, but I think she just sent it to Jeremyb

Good choice.

[pcimage]

@jeremyb if you’re listening!

Please report back on what you find

[fzabkar]

I don't know whether regular tools or software can read an SD card in SPI mode, but this would be my approach if it were not the case.

Code:

        SPI flash reader

              ^
              |
              |

          IC socket
             ___
      CS --o| v |o-- Vcc
    Dout --o|   |o-- /Hold
     /WP --o|   |o-- Clk
     Gnd --o|___|o-- Din

              ^
              |  6 wires
              |
  /-------------------------.
/   .-..-..-..-..-..-..-..-.|
|.-.|C||D||G||V||C||G||D|| ||
|| ||S||I|| ||c||K|| ||O|| ||
|| |'-''-''-''-''-''-''-''-'|
|'-'                        |
|                           |
|          SD card          |
|          adapter          |
|                           |
|                           |
|                           |
|                           |
|        .--------.         |
|        |        |         |
'---------------------------'
             ^
             |
             |

          microSD

[Arch Stanton]

OMG, this thread rules, we even got ASCII art now

[linuxversion]

I think it's work noting that all standards compliant SD and MicroSD cards can be read in 1-Bit mode by insulating D1, D2, and D3 from the reader. The raspberry pi also has a 1Bit SD mode overlay for its GPIO pins - you can solder those lines directly to the card and get more control over the frequency the card is read at (from 100KHz to several MHz).

[fzabkar]

ISTM that if the fault is at point X, then the data should be recoverable in SPI mode. A fault at point Y (on the 32-bit bus) would appear in both modes.

Parallel output mode -- 32-bit data multiplexed onto a 4-bit bus

Code:

                            32-bit bus ( 8 nibbles )

/------------------------------------------------------------------------------------------\
\------------------------------------------------------------------------------------------/
  |     |     |     |          |     Y     |     |                    |     |     |     |
  |     |     |     |          |     |     |     |            Enable8 |     |     |     |
(---) (---) (---) (---)      (---) (---) (---) (---)                (---) (---) (---) (---)
.\ /   \ /   \ /   \ /        \ /   \ /   \ /   \ /    ,,,,,,,,,,    \ /   \ /   \ /   \ /
  O     O     O     O          O     O     O     O                    O     O     O     O
  |     |     |     | Enable1  |     X     |     | Enable2            |     |     |     |
  |     |     |     |          |     |     |     |                    |     |     |     |
  '-----------------'          '-----------------'                    '-----------------'
           |                 stuck bit  |                                      |
           |                            |                                      |
/------------------------------------------------------------------------------------------\
\------------------------------------------------------------------------------------------/

                                    4-bit bus

                                   DAT0 - DAT3

Serial output mode -- 32-bit data shifted into DAT0 via a 32-bit shift register

Code:

                 32-bit bus
/------------------------------------------------\
\------------------------------------------------/
    |         |                      |
    |         |                      |
    | .--o--. | .--o--.              | .--o--.
    '-|D S Q|-'-|D S Q|--- ....... --'-|D S Q|----> DAT0
      |     |   |     |                |     |
Clk --|>    |  -|>    |               -|>    |
      |  R Q|   |  R Q|                |  R Q|
      '--o--'   '--o--'                '--o--'

The above diagram is "simplified" -- a real shift register looks like this:

https://en.wikipedia.org/wiki/File:4-Bit_PISO_Shift_Register.png

[jeremyb]

Looking forward to getting it

I'll report back my findings...

[fzabkar]

If there is a stuck bit, then it should also affect the file system's metadata. So how is the user able to access any files at all?

[jeremyb]

If there is a stuck bit how is the NAND chip able to accept Read/Write/ID commands
The customer told me it was a CF card, not a SD card.

[fzabkar]

If there is a stuck bit how is the NAND chip able to accept Read/Write/ID commands :-)
The customer told me it was a CF card, not a SD card.

A CF card use 8-bit taskfile registers for ATA commands and a 16-bit register for data. I have seen plenty of HDDs with a stuck bit on the IDE interface, but this problem looks different. It still seems like a controller problem, though.

BTW, it is possible for a bit to be stuck when reading the bus but not when writing to it. That's because different gates are involved, and each gate is separately enabled.