RPi rev 2.0 explained

I noticed immediately that there are three "cpuinfo" codes reserved for RasPi 2.0: 4, 5, and 6.  The obvious guess is that they're for Model B 2.0, Model A, and Model B w/ 512MB.

John Beetem wrote:

 

I noticed immediately that there are three "cpuinfo" codes reserved for RasPi 2.0: 4, 5, and 6.  The obvious guess is that they're for Model B 2.0, Model A, and Model B w/ 512MB.

Maybe they already found another issue, so the codes are for Model B 2.0, Model B 2.1, Model A 2.1.

The PoP RAM is mobile LPDDR2 400MHz 1.2V in an FBGA168 package, 32bits wide.  Digikey prices for 1000 quantity are $15.20 for 256MiB, $24.48 for 512MiB.  (And $36.72 for 1GiB, but we think the SoC does not support that.  They do not even sell 128MiB any more.)

Those prices are not tremendously meaningful, because nobody would buy this stuff from digikey, and it is not even a stocked item.  But it does seem very likely that a Model B+512 could be made for $50.  Whether the RPF would want to do it is another matter.  There is a risk of future software requiring the extra memory and failing to run on the hundreds of thousands of units already sold.  (It would be good for their rivalry with BeagleBoard/TI, though.)

> 1GiB, but we think the SoC does not support that.

Actually, Gert has explained that  the SoC will support 1GB,

but he didn't think any suitable 1GB PoP ram chips were available at the time,

which is I believe where the supposed 512MB limit came from.

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=2&t=3950&start=4

So it's possible that the version 4, 5, and 6 refers to 256MB, 512MB,

and 1GB. 

> 1GiB, but we think the SoC does not support that.

Actually, Gert has explained that  the SoC will support 1GB,

but he didn't think any suitable 1GB PoP ram chips were available at the time,

which is I believe where the supposed 512MB limit came from.

http://www.raspberrypi.org/phpBB3/viewtopic.php?f=2&t=3950&start=4

So it's possible that the version 4, 5, and 6 refers to 256MB, 512MB,

and 1GB. 

Good link, thanks.  In that case I think the Micron 512MiB part I was looking at may not be suitable, since it has two dice.  I can not get sufficient data from Hynix to determine if their 512MiB needs more than one chip select.  Samsung seem to have a suitable part, but their website does not show it in mass production.

I wonder why there is (has always been) reference to "Micron PoP 44nm 2x2Gbit" in start.elf, if this configuration cannot be addressed, however.

So when will they annonce the 512mib version?

I think this is the right Samsung part, and it does say it's

in mass production (since April, according to the press release).

http://www.samsung.com/global/business/semiconductor/product/mobile-dram/detail?productId=7609&iaId=747

http://www.samsung.com/us/news/newsPreviewRead.do?news_seq=20175

Hynix also has been showing mass production for a while on

its 4Gb lpddr2 parts:

http://www.skhynix.com/products/mobile/mobile.jsp?info.ramCategory=&info.ramKind=28&info.eol=NOT&posMap=MobileDDR2

coder27 wrote:

 

http://www.samsung.com/global/business/semiconductor/product/mobile-dram/detail?productId=7609&iaId=747

 

http://www.skhynix.com/products/mobile/mobile.jsp?info.ramCategory=&info.ramKind=28&info.eol=NOT&posMap=MobileDDR2

Yes, that seems to be the right samsung part.  I think I was looking at this page, which on reinspection seems to date from around the time of the transition to 46nm: http://www.samsung.com/global/business/semiconductor/minisite/Greenmemory/Products/LPDDR2/LPDDR2_Lineup.html

I did find that hynix page, but I could not tell whether the 4Gbit part had one die or two.