RPi rev 2.0 explained

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

I think a great use for the P5 header is a 16x2 display.  The display only needs 4 lines, 5v, 3v3 and a GND - Perfect!

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.

For a typical parallel interface with a HD44780 or equivalent controller you need more than four, besides d0-d3 you also need two control signals

for enable and register/data selection.

-J

jamodio wrote:

 

For a typical parallel interface with a HD44780 or equivalent controller you need more than four, besides d0-d3 you also need two control signals

for enable and register/data selection.

 

-J

You are right. It is 6 GPIO lanes, 5v and GND.  Should have checked my facts. http://learn.adafruit.com/drive-a-16x2-lcd-directly-with-a-raspberry-pi

srry.

Still an extra 4 GPIOs and a 5v will help the cause.

Here is another view of the Rev 2 board ...

-J

jamodio wrote:

 

BTW, what is their interpretation of a major revision ? Calling this new board 2.0 is a big joke.

I would think that anything that affects software is a major revision.  Substituting Ohmless links for F1 and F2 and removing D14 doesn't, though it it useful to know which board is which for fault analysis.  OTOH, when you're moving I2C channels around and adding I2S, some software needs to know which rev it's running on and apologize profusely if it can't run on rev 1.x.

IMHO a major revision is when you make major changes. It is very positive that finally they admited that the first production version had issues that needed to be fixed, and some of the fixes required some changes on the PCB layout.

Even switching the I2C is not really a major change. Some open issues that call for a major revision could be for example a better power management design, get rid of the micro USB connector, better layout with connectors in line and not all around the board, add more GPIO/interfaces from the SoC, RTCC, switch to a microSD, etc.

Still one thing I find hard to understand is why they keep releasing information in small bits, where is the new schematics, gerbers, etc. It is quite interesting that for-profit companies like Olimex give you complete access to their designs, while a non-profit organization such as RPF does not.

One thumb up for the changes, but still work to do ...

BTW, Amazon released yesterday the e-book version of the User's Guide, which now is outdated

-J

As far as I can tell, the minimum increment on their version number seems to be 1 (not something like 0.5), so this is a rev 2, a minor revision. And they must have been working on it for while, since some are already in punters hands, so thinking back, the board changes must be probably 2-3 months old at least (to get through re-design, prototyping and testing etc), so even though they didn't announce anything, they have been working behind the scene to fix stuff for a while.  I guess that's how most companies work - can't think of many companies that actively announce problems in their product they are going to fix until after the event.

BB

OTOH, when you're moving I2C channels around and adding I2S, some software needs to know which rev it's running on and apologize profusely if it can't run on rev 1.x.

Not just software, it'll be a problem for hardware too

Has anyone seen any proper explanation of the reasoning behind moving the I2C channels ?  Not sure if I missed something, but I don't see anything in the datasheet to suggest there's any difference between them, so not clear why the switch was necessary.

Did a pinout of P5 get posted ?  Or do we have to wait for someone with a new board and a multimeter ?

It seems such a pity that they didn't align the network & usb sockets with this respin. My feeling is that this will never be fixed now, possibly so that they don't annoy case designers.

And to think I just dropped in to see if anyone knew if the lan9512 1.8v supply had been fixed.

Oh well, at least I don't feel so guilty about wanting to cast one in clear resin like http://runawaybrainz.blogspot.co.uk/2012/04/audio-crystal-cmoy-freeform-headphone.html anymore