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ykc0
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Rookie
fingerprint sensor data
ykc0   9/27/2013 2:51:48 PM
Using SRAM to store fingerprint data? Reference data or scanned input? I would have expected a secure NVM. SRAM is volatile...

Kinnar
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CEO
Re: fingerprint sensor data
Kinnar   9/28/2013 5:15:08 AM
I am also wondering why at all fingerprinting data needs to be stored inside a processor. It is human fingerprint Or this fingerprint is referencing some other technical term?

Jack.L
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CEO
Fingerprint data storage
Jack.L   9/28/2013 2:45:37 PM
With the exception of law enforcement, I am not aware of anyone storing a full finger print image for verification. All that would be stored would be a short term image and 3 megabytes seems rather large.

For security, all that should be stored is a fingerprint signature. This is more than adequate for verification and removing false positives, but makes it pretty much impossible to recreate the fingerprint.

wilber_xbox
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CEO
Re: Fingerprint data storage
wilber_xbox   9/29/2013 1:00:15 PM
Apple patented the fingerdata verification techinique for mobiles in very recently infact in 2012 they filed for the patent. I do not know where they store this information but 3MB looks rather too much for just few fingerprint.

rick merritt
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Author
Re: Fingerprint data storage
rick merritt   9/30/2013 12:14:23 AM
I'm guessing the 3MByte is L3 cache or perhaps a private frame buffer memory for the quad core GPU.

Bastian.Schick
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Rookie
Re: Fingerprint data storage
Bastian.Schick   9/30/2013 3:50:44 PM
I have to say, that I doubt it is 3rd level cache. For one, it is to far away from the 2nd level cache. Second (correct me if I am wrong), I never saw an ARM architecture with 3rd level cache.

Also, I doubt it is GPU framebuffer, as it is far to small.But I think it is a GPU cache. It is directly between the GPU-SDRAM interface and the GPU..

Frank Eory
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CEO
Re: Fingerprint data storage
Frank Eory   9/30/2013 4:01:12 PM
Bastian, that -- GPU cache -- is the most logical argument yet.

rick merritt
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Author
Re: Fingerprint data storage
rick merritt   9/30/2013 8:13:47 PM
Agreed, this ~3 MByte block is probably a GPU cache

ExEDA
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Freelancer
A7 Chip large SRAM array and the CPU complex
ExEDA   9/27/2013 3:41:29 PM
Looking at the layout, Apple appears to have used 1 DDR channel to feed the CPU and another channel for GPU data. The large SRAM above the GPU appears to be the embedded cache for graphics memory, which is similar to approach used by Intel's IRIS Pro and XBOX One

To store finger print data? You need to use NVM, not SRAM or you have to keep feeding power to the chip, which is not possible


Also for the CPU highlighted by chipworks, it appears that the complex includes 2 memory controllers from layout, so the actual area for the CPU complex (excluding the memory controller) is likely smaller than 17% or ~17 sq mm

 

luting
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CEO
Large on-chip RAM
luting   9/27/2013 3:52:09 PM
It makes more sense to me this large on-chip RAM is L-3 Cache for DRAM controller directly next to it. If I am Apple, I will never store direct finger print data in anywhere. Because wherever you store, people will figure out. A good choice is to apply special imaging hashing function to it and only store hashing value. Not sure this technology exist today.

Frank Eory
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CEO
Re: Large on-chip RAM
Frank Eory   9/27/2013 6:42:58 PM
I have to agree, storing fingerprint data in SRAM doesn't make sense. L-3 cache is a better guess.

jaybus0
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CEO
Re: Large on-chip RAM
jaybus0   9/28/2013 12:09:48 PM
Yes. Dedicated SRAM for the GPU would make sense.

Bastian.Schick
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Rookie
Re: Large on-chip RAM
Bastian.Schick   9/30/2013 3:53:39 PM
They do not store the fingerprint itself. Rather they store a hash value which is smaller than the actual scan data.

luting
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CEO
256KB L-1 Cache?
luting   9/27/2013 3:54:22 PM
That doesn't make sense. L-1 Cache latency is critical and large SRAM has performance issue. Typical L-1 Cache is 32KB. 256KB is too big to me.

ExEDA
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Freelancer
Re: 256KB L-1 Cache?
ExEDA   9/27/2013 3:59:31 PM
Apple has presented that A7 has 64KB I-Cache and 64KB D-Cache per core. So 64+64 x 2 = 256KB

_hm
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CEO
Time and Money
_hm   9/28/2013 8:48:42 AM
How much time (man hours) and how much money is required to develop this type of SoC? This is very sound approach as it keeps secured technology and profit.

Will Google or Microsoft will take this route to develop their own SoC? IBM or AMD can help them.

 

Caleb Kraft
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Blogger
Re: Time and Money
Caleb Kraft   9/28/2013 9:53:55 AM
I doubt google will jump in at this level any time soon. they've typically partnered with a hardware vendor for this kind of stuff, like microsoft. I do know they have custom hardware made for their datacenters though. 

Who knows with google, they don't tend to follow a narrow path forward, so they might decide to experiment with SoC development of their own. 

_hm
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CEO
Re: Time and Money
_hm   9/28/2013 8:20:39 PM
Google did Android! Now it is time for them to make big dive in to making its own SoC. To get head start, they can buy some vendor in that field.

alex_m1
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CEO
Re: Time and Money
alex_m1   9/29/2013 6:25:09 AM
Soc wouldn't be a good investment for Google, for that amount of money (few hundred millions at least) they can achieve amazing feasts in many areas, while a soc gets only a small relative and temporary advantage. And anyways, they managed to get unique features in their soc in the motox phone by working with others, so it's seems good enough.

KB3001
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CEO
Re: Time and Money
KB3001   9/29/2013 6:46:55 AM
That would be madness IMO. Google should focus on what they are good at (software, search technology) and partner with others in other areas. Buying Motorola Mobile was a mistake in my opinion, so to go for the SoC design business would be madness for me....

AZskibum
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CEO
Re: Time and Money
AZskibum   9/29/2013 8:44:30 AM
But they bought MMI for the patents more so than for the hardware. Still, now that they find themselves in the hardware business, an SoC should not be automatically ruled out. There is always a cost/benefit analysis to be done, product differentiation, etc. It really depends on Google's strategic plan with that business, and how the relationship with its Android partners factors into that plan.

krisi
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CEO
SRAM for finger
krisi   9/28/2013 10:33:15 AM
SRAM used for finger image storage? How would that work? SRAM loses its content without power

KB3001
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CEO
Re: SRAM for finger
KB3001   9/29/2013 6:50:41 AM
There must be a misunderstanding somewhere, this can't be right..... 3MB and of SRAM for secure storage ..... of fingerprints?? Surely not....

elctrnx_lyf
User Rank
Manager
Re: SRAM for finger
elctrnx_lyf   9/29/2013 11:36:10 AM
Why it needs to be SRAM in any case? But there is a very high probability that they need fast accessible memory for the user to feel the login is as fast as swiping finger across screen.

krisi
User Rank
CEO
Re: SRAM for finger
krisi   9/29/2013 11:41:53 AM
I guess finger signature is stored e2prom and after power up gets downloaded to the SRAM for faster user login in.... So the question remains why 3Mb is needed

KB3001
User Rank
CEO
Re: SRAM for finger
KB3001   9/29/2013 11:50:42 AM
Exactly, why 3MB!!?

wave.forest
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Manager
The 3MB SRAM may be an image data buffer for GPUs
wave.forest   10/1/2013 7:57:02 AM
It may not be the GPU cache since to support cache mechanism, a cache controller is needed. This big SRAM may be an image buffer, say, to be used as ping-pong buffer, to process HD videos.

In addition, I agree it doesn't look like an L3 - not only too far away from CPU, but also no controller connected.

rick merritt
User Rank
Author
Re: The 3MB SRAM may be an image data buffer for GPUs
rick merritt   10/1/2013 3:44:20 PM
One engineer with a background at mobile SpoC companies told me today its closer to a 4 Mbyte block than 3MB. He also said he believes its a L3 cache.

jamescpwang
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Freelancer
Re: The 3MB SRAM may be an image data buffer for GPUs
jamescpwang   10/2/2013 10:45:31 PM
Apple and tsmc rescue Apple iPhone 5S fingerprint identification chip.

The article was published in DigiTimes on August 12, 2013 in Chinese and the partial abstract is translated in English and listed below for your reference:

1)      Fingerprint ID chip production was not ready until July, 2013 by assembly issues in Xintec. The original mass production schedule of the ID chip was in May, 2013.

2)      Apple sent technical people to Taiwan and work with tsmc engineers to solve assembly and test issues in Xintec (wholly own OSAT by tsmc).

3)      Apple iPhone 5S fingerprint ID chip gets 30,000 8" wafer per month capacity from tsmc.

4)      The schedule delay may be related to a) the incompatibility between IOS7 software and ID chip hardware; b) ID chip is interfered by Sapphire blue paint and c) the new assembly methodology that results in very low yield.

5)      Both Apple and tsmc have confidence that the low yield problem will be solved and the mass production will be started by the end of August.

This may imply that the 3MB SRAM is not for storing fingerprint data and the separated fingerprint ID chip may have EEPROM on 8" wafer.

Noko0
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Freelancer
Fingerprint data storage
Noko0   10/5/2013 10:08:53 AM
Fully in line...look for NVM not for SRAM. so rather look into M7 (which has both large quantity of embedded flash, and encryption capability). PS: it would be worth to have floor plan analysis of M7 as well, and get evaluation of technology used and embedded flash size.

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