Research question

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Could a single loose contact, between the copper pads of a 16Gb SDHC-card and the internal card slot of a Canon Powershot SX 270 HS camera, exactly reproduce the “missing IMG_509” end-state situation ?

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This end-state is achieved when:

• an image number x is skipped and is nowhere to be found on the SD-card;

and

• the last memory cluster of image number x-1 and the first memory cluster of image number x+1 are contiguous.

I use the words ‘photo’, ‘picture’ and ‘image’ interchangeably.

TEST SET-UP

Canon Powershot SX 270 HS

Firmware: 1.0.2.0, June 4th, 2013

Factory settings

SanDisk 16Gb

SDHC Ultra

DIP-switch

10 x

SDHC extension cable

(cut in half, circuitry on next page)

USB smartcard

reader

SDHC extension cable

Jopto 18.9 "48 cm

Various

Software tools

PC /

Laptop

CARD

READER

EXTENSION CABLE CIRCUITRY

DIP-switch

1

2

3

4

5

6

7

8

9

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

CARD

Flat cable

NOTES

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• The SD-card extension cable is a flexible flat cable consisting of 15 wires. Clock, CMD and data wires are seperated by a ground line to avoid interference.
• The diagram above outlines the mapping to be made, so that the DIP-switch numbers exactly match the SD-card pins.
• Note that both pin 4 and pin 7 are labelled as “ground”. Pin 7 could in theory be used for a negative voltage, however is typically connected to “ground”.
• Pin 4 and 7 could be tested in one go to interrupt the ground wire(s). Therefore a total of only 8 pin tests needs to be carried out.

THE MEMORY CARD/BATTERY COVER MUST BE CLOSED

NOTES

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• The camera will not switch on when the cover of the battery / SD-card compartment hasn’t been fully closed.
• The flat cable prevents it from being closed and the tiny switch can’t be operated, hence a pragmatic solution was applied.

Tiny switch

Hair pin

HOW THE CAMERA ORGANIZES MEMORY ON THE SD-CARD

512

512

512

512

512

512

512

512

512

512

Sector 1

Cluster 1

64 x

512

512

512

512

512

512

512

512

512

512

Sector 65

Cluster 2

64 x

(FREE) SOFTWARE USED

End cluster #

previous file

Start cluster #

previous file

(divisible by 64)

PLANNED TEST APPROACH

ALL 9 SWITCHES ON (i.e. no loose contacts)

TAKE A PICTURE

TAKE A PICTURE

SWITCH #y TO OFF

TAKE A PICTURE

TAKE A PICTURE

SWITCH #y TO ON

TAKE A PICTURE

TAKE A PICTURE

y = 1 .. 9 (4 + 7 in one go, so 8 test runs)

Check results

OUTCOMES FOR ALL 8 TEST RUNS

ALL 9 SWITCHES ON (i.e. no loose contacts)

TAKE A PICTURE

TAKE A PICTURE

SWITCH #y=1,2,3,5,6,8,9 & 4+7 TO OFF

TAKE A PICTURE (“PHOTO SNAP” SOUNDS)

SWITCH #y BACK TO ON

With the camera ON, for each of the 8 switches set to OFF, the same error message is shown after a picture appears to have been taken successfully. The image-number gets skipped, leaves no traces on the SD-card and the memory cluster numbers of the previous and next pictures are contiguous.

=

“Memory card error”

SWITCH CAMERA OFF & ON

TAKE A PICTURE (ERROR SOUND BEEPS)

TAKE A PICTURE (ERROR SOUND BEEPS)

TAKE A PICTURE (ERROR SOUND BEEPS)

TAKE A PICTURE

TAKE A PICTURE

SWITCH CAMERA OFF & ON

TAKE A PICTURE (ERROR SOUND BEEPS)

TAKE A PICTURE (ERROR SOUND BEEPS)

Picture counted,

but not stored.

INTERPRETATION OF RESULTS & CONCLUSION

INTERPRETATION OF RESULTS

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1) The firmware of the SX 270 HS does a thorough check on each pin of the memory card. It does so:

• during the booting process of the camera (on/off and in play mode). If an error is detected, no pictures can be taken, the message “memory card error” is displayed and the camera can only be switched off.
• at the moment when a picture is written to the SD-card after it has been taken. If an error is detected, the message “memory card error” is given and the file number will be skipped. No further (skipped) pictures can be taken and the camera can only be switched off (ending in the state above).

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2) Any SD-card copper contact failure could induce these issues, i.e. a 100% score.

CONCLUSION

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The data do not support a scenario in which a fall or water damage induces a poor SD-card contact when the camera is switched OFF. In that case no pictures can be taken (nor skipped) when the malfunctioning camera is switched ON.

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The data do fully support a scenario where someone switches the camera ON, tries to take a picture, slips/falls and thereby induces a SD-card malfunction, picks up the camera, looks at the screen (seems all ok) and tries to take a quick picture to check the camera is still working. This scenario exactly reproduces the observed “missing 509” end-state.

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The research question is answered affirmatively for 100% of the individual 8 SD-card contacts.

APPENDIX A: DETAILED RESULTS