Yes, I suppose if you had an embedded application Compact Flash could be a useful mass storage format. But for the general commerical market, there is no reason to use anything other than SD cards or USB sticks. These formats may be limited to around 16 GB or so at the moment, but that is all I had on my PC some 5 years ago and a I would be very happy starting with that on such a portable unit today.
Compact Flash or any of the other memory formats are for niche applcations today and most will be gone in another two years. I think people will still be using floppy disks longer than most of these memory stick formats. (I still have an excellent camera that uses floppies).
I also saw mention of IDE 44. Is there room for an internal rotating disk drive like they use in the iPods?
It's here, available, ex-stock and cheap. It is what it is. I'm not advocating it for anything other than embedded or industrial use. At least CompactFlash has a mechnical standard, so you know what you are dealing with. As far as I know, USB sticks have no mechanical standard beyond the USB connector.
Yes.
Stephen
--
Stephen Pelc, stephenXXX@mpeforth.com
MicroProcessor Engineering Ltd - More Real, Less Time
133 Hill Lane, Southampton SO15 5AF, England
tel: +44 (0)23 8063 1441, fax: +44 (0)23 8033 9691
web: http://www.mpeforth.com - free VFX Forth downloads
It also has the advantage that IDE / SATA to CF adaptors are available at very reasonable prices (I bought 2 for a fiver off of eBay) and mean that they can be mounted internally to most PC cases.
And it has the big disadvantage that you can't plug it into most desktops or laptops without a special adapter. Unless you need a capacity that currently (this week anyway) exceeds what is available in SD format, I don't see any reason to go with such a large and clumsy format. I guess there are applications where you want users to be able to remove the storage and the SD or USB format is so small that they are likely to loose it. But then a CF sized box should do the trick for an SD card or USB stick, or a dozen.
Needing to have a mechanical spec for a USB stick seems to be an odd requirement. If there is not a spec out there, define your own spec for your mounting and specify a few units that meet that spec. This isn't rocket science.. at least I don't think it is. Are these things going on the shuttle?
I could live with the internal USB socket(s) 'borrowing' the IDE44 space - users are likely to want one or the other, and USB has widespread availability.
Rather less likely to find a fitting IDE44 drive at the corner store :)
Indeed not very likely but recently I was nicely surprised stumbling into 44-pin ATA (IDE) flash drives, starting at 1G around $20-25. Pretty good for a particular application I have - 1G won't get you very far in the wintel world nowadays, of course.
IDE44 drive like the 2.5 inch drives in a hell of a lot of laptops. Still lots of new ones about.
--
Paul Carpenter | paul@pcserviceselectronics.co.uk
PC Services
Timing Diagram Font
GNU H8 - compiler & Renesas H8/H8S/H8 Tiny
For those web sites you hate
That's nice, but $20 a GB is a bit rich these days. I expect you are paying for the novelty. I just think it is better to go mainstream as much as possible. So SD cards and USB memory is at the top of the list for my apps. The next time I design a processor board with Flash, it is likely to be a micro-SD socket. I get the absolute best bang for the buck that way and I never have to worry about availability or the parts being obsoleted!
I know SD cards are cheaper and widespread, I also was designing a slot for them in a project which got stalled (hopefully it will resume later this year, thumbs pressed :-). But the advantage I take of these particular drives is the fact that I can use one of them at $20 for 1G or say a 120G or 160G "normal"
2.5" drive at $80 still using the same connector... that's just device specific for me, I had planned the device without even knowing I would ever have the smaller/cheaper flash only option.
You're kidding, right? No two of those are the same, and the shelf life of any given model is about twenty minutes. You need a pretty big physical envelope, and some innovative anti-vibration strapdown system, to be able to accept any arbitrary USB disk.
I would think that *you* were kidding. The ones I have seen are pretty much the same. They are all about the size of a stick of gum. It is pretty easy to find models that don't include the fancy ejector connector, or the swing connector or the swing cover. Yes, there are lots of funny ones out there, but there are so many that are just plain jane that it is easy to find a dozen about the same size.
As to the strapdown, a strap would be perfect. Just a piece of rubber band or o-ring stretched across the body between two hooks. Very simple, very effective. Or if you need extreme vibration resistance, you can clamp a bracket on top of one with a piece of foam rubber as a cushion (and size adapter). I have seen this used for everything from electrolytic caps (of variable size) to PC bus cards (which are of a variable height).
If you *really* want to be extreme with your assembly, you can even leave the mating connector floating as a cable end so that you don't have to worry about stressing the connector. I expect that could actually fly on the shuttle!
Have you ever actually looked at them? Looking in the "spare USB stick" drawer right in front of me I see devices ranging from 0.75" long to 3" long, 0.25" to 0.75" wide and 0.25" to 0.5" thick. Some of them are asymmetrical. The ones that are asymmetrical have no standardization as to whether the thick side is "up" or "down" relative to the USB conncetor. This is precisely what is meant by "no mechanical standard".
Unless the body of the drive is properly supported at the bottom, you're applying bending stress in the worst possible way - levering the connector leads off the PCB using the mechanical solder-mounting points at the front as a fulcrum.
That is probably the best solution, I agree.
However, CF is in many applications a superior solution. Nobody (TTBOMK) makes industrial-rated USB sticks; industrial-rated CF cards (temp range and availability of spare sectors) are fairly easy to come by. The reliability of USB media isn't even characterized since they are all strip-mined out of the anonymous electronics rockface in China.
--
Lewin A.R.W. Edwards
Projects - http://www.zws.com/
Personal - http://www.larwe.com/
** Posted from http://www.teranews.com **
ElectronDepot website is not affiliated with any of the manufacturers or service providers discussed here.
All logos and trade names are the property of their respective owners.