Anyone knowledgeable about SD cards

I have an SD card in a camera. I want to use a controller to work the camera. The construction of the camera doesn't lend itself to just putting a scope on the SD card while it is working.

What I would like is some way to tell the controller that the picture the camera just finished taking is in memory and it is OK to shut off the camera. Is there some handshaking line that I could use to tell when the card is being accessed and when it is just sitting there waiting?

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On a sunny day (Sun, 09 Mar 2008 14:40:55 -0500) it happened default wrote in :

The card has a CS (Chip Select) line, when no activity there for some time you could take that as 'done', but there is a lot more to SD card protocols.

Reply to
Jan Panteltje

Perhaps this is the wrong approach. Most digital cameras have a USB port and expose a camera control protocol in addition to the contents of their SD card here.

There are some open source projects you can look at which will lead you to documentation on specific camera interfaces. GPhoto is one (used on Linux) I am familiar with.

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Paul Hovnanian P.E.

CS is only a momentary access line, not a good source to detect "Finish" signal.

Default, you have to look at the power line of your SD card or your Camera power source, if you want the external controller to shut off the camera then you're having a difficult task, it should be the other way around.

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Michael A. Terrell

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One idea -- possibly not the best?

Can you just use the flash on the camera as an "input" to your controller to know that the camera just took a picture, and then wait a reasonable pre-determined period after that flash for the SD to do it's thing? (In other words, set it up to use the flash, even if you don't need it for exposure, and key off the flash with a phototransistor.)

Note: I am assuming that the controller is not instructing the camera to take the picture and that the camera does that by itself in response to some other stimulus. Otherwise, this would be a rather circular approach. -mpm

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mpm

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Dead easy the LED flashes until the picture is in memory !

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Marra

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That would be self defeating but thanks for the suggestion. Just charging the flash capacitor would sap more energy than running the camera longer to allow for the pix to go into memory. I want to avoid a modification that prevents the camera from functioning normally.

The controller is telling the camera to take a shot - the length of time it takes to get the picture from the shutter click and safely into memory varies, and the controller doesn't have a clue when it is finished.

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I've done some reading looks like the chip select line has to be low to write to the card. With only one card, however, it can probably stay low 24/7 and work OK.

The controller does shut off the camera - I just want to make sure the picture is safely in memory before it shuts it off.

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Michael A. Terrell

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Break it with a hammer?

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Reply to
Michael A. Terrell

On a sunny day (Sun, 09 Mar 2008 19:04:29 -0500) it happened default wrote in :

Well, there should be a maximum time it takes, so timer. OTOH you could use a PIC to monitor the other SDcard lines for change (interrupt on change), after it stops changing it would be ready.

I dunno how sophisticated you are, as you cross post to basics, there are many ways to do this. The delay being the simplest.

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Jan Panteltje

messagenews: snipped-for-privacy@n77g2000hse.googlegroups.com...

Break it with a hammer?

Photo transistor sucked against it, you know.

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panteltje

messagenews: snipped-for-privacy@n77g2000hse.googlegroups.com...

Break it with a hammer?

Jan, You just replied to a forgery.

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
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Jim Thompson

messagenews: snipped-for-privacy@n77g2000hse.googlegroups.com...

Break it with a hammer?

Oooops! I just replied to someone forging Jan :-(

...Jim Thompson

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|  James E.Thompson, P.E.                           |    mens     |
|  Analog Innovations, Inc.                         |     et      |
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Jim Thompson

On a sunny day (Mon, 10 Mar 2008 09:43:47 -0700) it happened Jim Thompson wrote in :

messagenews: snipped-for-privacy@n77g2000hse.googlegroups.com...

Break it with a hammer?

Yes, possible, I posted via google groups this time for a change, and the whole thread seemed messed up somehow.

I see postings condemning aioe.org, that is not correct, I use aioe.org a lot, it is an open server, so killing aioe.org will also kill the good postings. Message ID changes with every posting, it comes from a random generator, except perhaps when the guy forges the headers, but message ID is added in aioe.org, I do not see how he could do that unless he had hacked that server. Best perhaps just to ignore the bad guy. I should have, but 'sucked against it, you know' was my hint at him/her/it.

Reply to
Jan Panteltje

On a sunny day (Mon, 10 Mar 2008 09:52:27 -0700) it happened Jim Thompson wrote in :

No you did not :-)

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Jan Panteltje

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