Deferring media removal

Hi,

I'm looking for removable media (card) "sockets" that either already support a mechanical interlock to defer removal of the medium *or* can be modified to make that possible (in a small space/volume).

Reply to
Don Y
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Any socket + hot glue

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Reply to
Nico Coesel

The operative word here is "defer" -- not *prevent*!

Reply to
Don Y

Hmm, this is turning into a semantic discussion. Because Webster's dictionary doesn't tell me what you mean exactly either: please explain what you intend to achieve :-)

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Reply to
Nico Coesel

"defer" or "deter". The former means to delay an action until some future date. The latter means to discourage.

No, I didn't bother to look either of them up.

If I understand what you're looking for, I don't know of any (thinking SD card here). I think you would have to put a removable cover over the card - i.e, part of the case. If you had a locking SD-type socket (for example), folks are so not used to that that they would probably damage the card trying to extract it. Hell, some folks don't even realize you should push-in before removing.

Reply to
mpm

defer: to put off; delay

I.e., I don't want the medium to be removed until I'm done

*accessing* (reading/writing) it.

Most memory cards appear to employ the user for the "motive force" to insert and extract the card. I.e., the "mechanism" isn't electromechanical but, rather, purely

*mechanical*. So, the user can insert or remove the card at will.

(I.e., old "disk packs" would not allow the user to remove the pack until the heads were unloaded and the platters spun down. Old floppy drives could be purchased with electromagnetic door latches to prevent the floppy from being removed until "allowed". Optical media -- CD/DVD/MO -- all have electromechanical mechanisms to load/unload the media -- again, effectively preventing the user from removing the media "prematurely".)

I need a means of "locking" the card in place. Since I've not seen an "electromechanical loader/ejector" for media cards (pick your style), it seems like I have to come up with a way of interfering with the user's normal insertion/extraction process (e.g., a "door" that I can hold closed; a pin that I can drop across the "card slot", etc.)

Reply to
Don Y

Defer. Postpone. Until is done using the card and its removal wouldn't compromise its contents or the operation of the system in which it is employed.

I don't need to constrain it to SD cards...

Or, a pin that drops into the slot preventing the card from being pulled out, etc.

The nicer solution would be a mechanism that ejected the card "on demand" (think of a CD/DVD tray opening when "requested" by pressing the front panel button). I.e., the eject could be delayed (defered) until such a time as the card's contents were no longer being accessed.

That's why the ejection mechanism would be a win -- you get used to waiting for the card to be *presented* to you (instead of trying to get it out, yourself!)

Reply to
Don Y

"hot glue" as i have seen it is rather crappy and does not stick too well - i would put it inthe "defer" category, not in the "prevent" category where superglue and epoxies go.

Reply to
Robert Baer

On a sunny day (Tue, 10 Apr 2012 19:35:41 -0700) it happened Don Y wrote in :

You could perhaps train some dog to guard the card while it is being accessed :-) Use ultrasound beeps, the dog can hear those humans not. Alligators would prevent access too, but are more difficult to train I guess.

Come to think of it: 2 electrodes with a 10kV spark, triggered by an IR proximity detector. The solutions are endless. The last thing has no moving parts, I vote for it :-)

Reply to
Jan Panteltje

:-)

Slightly OT, I have often said that a stand alone Windows NT/2000/XP system is a quite usable soft real time platform (about 1 ms predictability) as long as you have full control who is going to access the system.

One way to avoid any unwanted access is to fill all serial, parallel, keyboard, mouse, USB and Ethernet ports with glue.

The other alternative is to use dogs to prevent any unacceptable access to such computers. Unfortunately, in order to train the dogs, you would need a large supply of hackers to feed the dogs :-).

Reply to
upsidedown

If I were in your shoes I'd do almost anything to avoid needing to implement your mechanical lock. If you want to be truly hated by end users, go ahead. If you want lots returns of broken equipment, go ahead.

NT

Reply to
NT

snipped some author names... ooops

Any time a mil design uses a storage element like a CF or such, the location where the interface 'slot' is attached also has elements to fix the card/chip in place after insertion. Just like batteries have holders.

You need to use your brain. Every application has its target demographic.

Stupid putzes do not buy card readers with locking doors/hats.

Professional/commercial customers, however, might do just that.

Reply to
MettleBeerStolid

It is a "voiced complaint" (deficiency) of existing products: "Do not remove power to the device until after the BUSY light stops flashing. Memory contents may be corrupted." Obviously, a blinking light isn't enough to deTer (!) these people from the problem.

A "proprietary" memory module defeats the economies of COTS memory "cards". It adds lots of bulk. And, as capacities increase by orders of magnitude, the vulnerable window gets uncomfortably long -- almost *guaranteeing* the above advisory will be violated.

So, paraphrasing: If I want to be truly hated by end users, go ahead (and ignore their complaint). If I want lots returns of broken equipment (and dissatisfied customers), go ahead. It pays to not second-guess your market and heed research therein!

Reply to
Don Y

If the problem is they are pulling power while you are writing then you have a different problem. No scheme of locking the card in place is going to solve this issue. You need to have enough stay up power to complete your writes.

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Reply to
Joe Chisolm

I can address that. I can let the device decide when to power itself down (i.e., the power button becomes a "power request").

However, if the user can remove the medium, all the work I do to keep power *up* won't help me. I.e., the light will be merrily blinking AFTER the medium has been removed :-/

I.e., the NEW warning (in the absence of a "medium lock") becomes: "Do not remove the memory card from the device until after the BUSY light stops flashing. Memory contents may be corrupted." To the user, it's the same situation with just a different warning message -- you don't get "credit" for fixing the "power problem" if you've just turned it into a "memory problem"! :>

(Sort of like MS "fixing" the UAE problem in W3.0 -- by renaming them as GPF's in W3.1, "illegal operations" in W9x, etc. :-/ )

Reply to
Don Y

If "defer" will be ok if it is only gives you a second or so, do what Nokia did with the n800 -

Put a door over the sd slot, door has a magnet, board has a reed switch, when the door opens, stop writing and clean up the card directory.

Reply to
xpzzzz

Need much longer time than that. Imagine writing pretty near the

*entire* device in one burst. Then, look at the sorts of *sizes* you can expect in the near future for these devices... :<
Reply to
Don Y

Is there some kind of user interface on this device? Can't you make the user wait until writing is finished? Maybe by letting the user do something totally bogus?

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Reply to
Nico Coesel

Reply to
MettleBeerStolid

The user is "done" and wants to move on to . That's what acts as the impetus to remove the card prematurely.

E.g., most of the time, when I am using a digital camera, it's to take *a* picture. Then, *do* something with it (email it, paste it into a document, etc.).

Each of my cameras has some sort of "computer interface" (e.g., USB) through which I could "download" the image. But, experience has taught me that getting out the cable, connecting it, waiting for the PC to recognize the device, finding the folder corresponding

*to* the card in the camera and dragging the image to takes MUCH longer than removing the SD/CF/etc. card and shoving it into a card reader (already tethered to the computer).

Often, the memory card hides behind a door that also provides access to the battery compartment. I can flick this door open (operating the latch and counting on the spring tension in the battery holder to PUSH the door open) almost instantaneously (doing it so often results in a sort of "muscle memory").

Experience (mostly *bad*!) has taught me that I have to deliberately wait for the memory card to be written. Then, power down the camera.

*Then* open the battery/card door. Otherwise, I end up with a botched photo.

It's only a few seconds (3 or 4?) for the entire process. Yet, it is something I am keenly aware of each time it happens. *I* am waiting for the technology. And, if I jump the gun the slightest bit, *I* pay for that (my!) mistake -- shoot another photo, etc. (which means powering the camera *up*, again; reframing the photo; snapping the photo; FORCING MYSELF to wait the prescribed shutdown interval; etc.)

And, it ties up my full attention for that process. Not because there is some tricky mechanical maneuver that I am negotiating. Or, some important *data* that I need to examine/review in the process. No, I'm just *waiting* for lights to stop blinking and the lens motor to retract the optics!

If, OTOH, I could push a button and wait for the card to come popping out into my hand -- or, wait for a catch to release on a door on which I am exerting gentle pressure -- then I could "move on" to whatever other activity interests me while keeping a "background mechanical (organic) process" running to extract the card.

Now, imagine the "second or two" is replaced by a lengthy process. Do *you* want to sit there watching a light blink? Or, would you rather some other "low cognitive loading" means of getting the medium out? Do you sit and watch your PC shutdown?

Reply to
Don Y

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