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Anyone knowledgeable about SD cards

D

default

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?
 
J

Jan Panteltje

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?
Click to expand...

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.
 
P

Paul Hovnanian P.E.

default said:
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?
--
Click to expand...

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.
 
M

Michael A. Terrell

Jan Panteltje said:
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.
Click to expand...



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.


--
Service to my evil master? Been there, Done that, and I've got my DD666 to
prove it.
Member of DAV #666.

Michael A. Terrell
Central Florida
 
M

mpm

I have an SD card in a camera. �I want to use a controller to workthe
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?
Click to expand...

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
 
M

Marra

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?
Click to expand...

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

default

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
Click to expand...

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.
 
D

default

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

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

Michael A. Terrell

Michael A. Terrell said:
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.

--
Service to my evil master? Been there, Done that, and I've got my DD666 to
prove it.
Member of DAV #666.

Michael A. Terrell
Central Florida
Click to expand...


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
M

Michael A. Terrell

Jamie said:
Why don't you two shit eaters get lost? I don't give a shit about your personal conflict.
Click to expand...


Why don't you grow up, Jamie?


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
M

Michael A. Terrell

Jamie said:
Dead easy the LED flashes until the picture is in memory !

Good point dundfuck, the question is, how do you get to the LED in a camera? Break it with a hammer?
Click to expand...


--
Service to my country? Been there, Done that, and I've got my DD214 to
prove it.
Member of DAV #85.

Michael A. Terrell
Central Florida
 
J

Jan Panteltje

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.
Click to expand...

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.
 
J

Jan Panteltje

Jan, You just replied to a forgery.
Click to expand...

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.
 
R

Rich Grise

Weenies never grow up. Unfortunately they never seem to die off
either :-(
Click to expand...

Of course not, with idiots like you two encouraging them.

Feh.
Rich
 
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