Slashdot Mirror
Engineers Devise a Technique To Fight Counterfeit or Recycled Smartphone Memory (ieee.org)
Flash is designed to last a decade or more of use. A lot of the gadgets that rely on it, however, are not. Shady recyclers have spotted opportunity in that mismatch, stripping out used chips and selling them as new. But fret not, there is something that can be done to address the issue. From a report: Engineers at the University of Alabama have come up with a straightforward electronic examination that can tell if a flash chip is new or recycled, even if that chip has only seen 5 percent or less of its life. And the technique is so straightforward that a smartphone app could run it on its own memory. [...] A flash memory cell is like an ordinary transistor, it has a source and a drain and a channel through which current flows under the control of voltage on the gate electrode. The difference is that the gate is split into several layers -- the control gate, the blocking oxide, the floating gate, and the tunneling oxide.
[...] Voltage on the control gate causes electrons to tunnel through that bottom oxide and get stuck inside the floating gate. This charge or its absence is the stored bit. It alters how much voltage you need to turn the transistor on in a way that you can easily measure. Erasing the bit is done by reversing the voltage and driving the charge out of the floating gate. Ray and his team took advantage of the rather high voltages -- about plus or minus 20 volts -- needed to program and erase flash. The more you program and erase a cell, the more defects will accumulate in the oxide, he explains.
[...] Voltage on the control gate causes electrons to tunnel through that bottom oxide and get stuck inside the floating gate. This charge or its absence is the stored bit. It alters how much voltage you need to turn the transistor on in a way that you can easily measure. Erasing the bit is done by reversing the voltage and driving the charge out of the floating gate. Ray and his team took advantage of the rather high voltages -- about plus or minus 20 volts -- needed to program and erase flash. The more you program and erase a cell, the more defects will accumulate in the oxide, he explains.
Wouldn't it be more productive to create positive channels for recycling the flash memory? There are plenty of usage cases where the reduced performance would be unimportant, and the reduced cost would be attractive. If you want to stop "shady recyclers," the obvious solution is to bring them into the sunlight.
This is my signature. There are many like it, but this one is mine.
If you're going out of your way to detect whether a flash part has even just 5% use on it [as proof of it being pulled from a previous installation] then I have to question the motivation here. For sure reuse should be disclosed but it also shouldn't be prevented.
How much wear and tear does the flash memory in the typically device actually take? Now that that amount of RAM on these phones is sufficiently high (The newest Android flagships have 4 GB now) there shouldn't be as much need to use the flash memory for a pagefile or something of the sort. I'm not even using 64 GB on my phone (most of it is music which is just going to be read from) and that's what comes standard on most flagship devices these days.
I suspect that a lot of this used flash would still outlast the expected lifespan of the device for most people. I can even see the recycling companies using this technique themselves to sell the recycled chips in different bins based on use. The article doesn't describe the extent to which people are getting worn out flash memory, and I suspect it's not a particularly big issue.
And the memory is used. With 100% confidence!
Do write and erase until it is broken and you know have many cycles it had left.
Apparently you can reset the flash cells' use count by adding circuitry that does a heating thing. Those can be safely recycled, and the problem with re-used flash sold as new goes away.
And maybe we should start and design the devices to last a bit longer than we currently do, too. My nokia 6310 is still going strong (needs new rubber and new battery), and I see no reason to replace it. Why aren't we even trying to make designs that good? Instead all you get is stupid little gimmicks like rounded corners or notches in the screen. What does that buy me, exactly?
This is anti-consumer. No upgradable parts!
Apple has designed their phone/tablet devices so that it is nearly impossible to replace or upgrade the internal flash memory.
Many android devices do the same thing.
Of course, Apple does this so that you will pay their inflated prices for commodity flash memory.
Some android devices come with a microSD slot, which lets you buy commodity 128 GB microSD cards from amazon or any other source.
They don't want you to fix the devices that you own. They don't like that plebeians can own stuff. If it makes some kind of crime harder that is just a cover story.
If the recycled memory performs up to specification, and lasts the lifetime of the device it is recycled into.. why do we give a crap?
Apples says that any 3rd party repaid in now an Counterfeit apple device
Describing this as detecting unreliable Flash memory: good.
Describing this as detecting recycled/repurposed/cannibalized Flash memory: evil/stupid.
All you had to do was try to not sound evil/stupid, but you couldn't. Oh well.
... kill a piss ant.
It little behooves the best of us to comment on the rest of us.
How would a recycle flash chip get back into the manufacturing supply chain of any reputable manufacturer? It strikes me that flash chips would not be the only problematic part being used by disreputable manufacturers.
How nice it would be if at least technical sites such as Slashdot could get straight the difference between memory/RAM and SSD/flash storage.
Due to the wonders of the internet you can go on Ali Express or Ebay and order all sorts of electronic wonders from china REAL cheap. If you're a maker or a hobbyist you've got more available to you than ever before, for fractions of a penny on the dollar of what it used to cost 10 years ago.
When you order certain things that /should/ be pricy but are not more often than not you get something that contains recycled pulls. IGBTs, relays, things that come as packaged "modules" for integration - Like GPS modules, DiskOnChip modules, cell modems, solid state relays, potted DC-DC converters
This has its up and downs. On the down,you're getting something that's of unknown condition.. On the up,you're getting something for 5-10 bucks that costs 50-100 new. (If you can even order it as an individual at all)
You see a lot of this for hobby stuff. A big example is GPS modules - The packaged GPS module will be pulled and re-soldered on to a minimal breakout board with a voltage regulator ready for use in your project (Drones are really popular application for this)
The new iphone update will contain a routine to brick the iphone if it was repaired. After all, why would people buy new iphones if they could simply repair their old ones?
The notion that a smartphone app can do this test doesn't hold up to scrutiny. I don't think even the operating system could do it in most cases.
Both of the techniques described require the testing tool to be able to measure the effects of wiping or rewriting a given page. But modern flash hardware doesn't provide any way to operate on a specific physical page, only on logical pages which the hardware reallocates to different physical locations. Pretty much any time you try to erase a block of flash, what the hardware will really do is give you an already-erased block.
And, of course, apps don't have access even to logical blocks, they have to work through the file system. File systems designed for flash add another layer of shuffling, and even general-purpose file systems often do some amount of reallocation.
Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.
Flash erase wear-out, especially at low temperatures during the erase cycle, has been well-known for many years. I first encountered this circa 1991, during qualification of Intel 28F010 NOR flash for an extended temperature application. And again during qualification of AMD flash to replace this, because Intel had many months of production gap due to a botched fab move to a partner fab (Nippon Steel, I believe), that turned out to be incapable of producing the device.
Disturb during write is also well-known. I suspect that the behavior and mechanisms here are different for modern NAND than they were for NOR.
The best relevance of the work would be in situations least likely to use it: small volume products without good traceability in sourcing.
It is nice to see some actual technical info in TFS.
"When the going gets weird, the weird turn pro" -- HST