Raspberry Pi - Hardware Flaws and Fixups?

Now that people have actually started receiving the boards so the design in final, is the schematic close to being posted?  I looked around again in various likely places just now, but haven't spotted it yet.

actually, the design may not be quite final yet.  Liz said: "Happily, we’ve found it doesn’t need a shielded enclosure to reach Class B, although it will require a (very minimal) redesign." http://www.raspberrypi.org/archives/978, page 3, April 10, 2012 at 7:04 pm.

It hasn't been announced when such a change might be implemented, but probably better sooner rather than later, given the large production runs planned, perhaps along with a change to fix the SD card voltage issue.

Looking at the article it looked like this is a stacked die ('chip') application inside a single package - should have made this clear in the previous post.  The BGA ball array is set up for Standard Mobile and not to sit on a POP architecture so I think we are out of luck here.

Pete

Even then...

It seems ARM code is pretty compact. I've compiled programs that seem to come out to 5 and 6k. That's nice.

Why do you NEED 1Gb of RAM?

A few weeks ago I was annoyed at my browser using over 1G of RAM. Then I calculated: It might cache a bitmap of that page for when I switch to that tab. I'd be annoyed if it would re-render it from the source if I switched tabs. If I Have 200 tabs open, a megapixel per page comes to 600 Mbytes.... A gig and a half isn't that bad for some overhead.

After loggin in a few times over the ethernet, I see the 'pi not touching the SD card to log me in. Everything needed has been cached. That's what it is supposed to be like.

Arduino-like board         raspberry pi.

16k flash.                     16G. (4G?)

2k? 4k? RAM                256M

serial 115k2                  USB 480Mbps

16x2 LCD on 8 pins       HDMI out / anallog video out.

No OS                          good OS.

To be able to run X I equipped my '486 machine with 8Mb instead of the standard 4Mb back in '91. A few years later, I had upgraded to 20 and then 32 Mb RAM and a new motherboard, I was swapping RAM modules around, and I thought my machine had crashed with the HDD led stuck on when the X weave showed up. Turns out the 32M was on the other motherboard I had forgotten to swap back: I was booting into X with 4Mb of memory. Things have bloated a bit. A kernel is now about 10x bigger than back then. A video card is no longer satisfied with "enough RAM to put the framebuffer in".

We've come a long way since then. The Raspberry pi is a nice machine with a whopping 256Mb of RAM. And because of the way it is built it can be sold cheap. And because of the way it's built, there is no system bus or memory slots. Tough luck.

Pete, While on the subject of RAM.... I've been running with a 208 / 48 split the last few days. How are my chances of running 240/16 ? I'm currently using a 656x416 framebuffer: No HDMI connected. Less than 300k pixels. i.e. a total of 1.2Mb for 32 bits per pixel (I can understand a GPU not supporting 24 BPP as it's a pain in the $%% (*))

(*) For the non-hardware guys, suppose you want to turn on the pixel at 101,101... Turns out that pixel is spread out over two 32-bit words. Really a mess to do.  Slows things down too. Best case, you have to do two writes to the framebuffer to turn on one pixel. Worst case you have to do two reads as well and delay those writes until you've gotten the results of those reads!

P.S. Look at: http://www.hynix.com/gl/products/mobile/mobile_info3.jsp

You can see there that they have up to 2Gbit of POP memory. About two years from now they will have 8Gbit and we can upgrade our 'pi to 1Gbyte of RAM.

Roger,

   you ask "why do you NEED 1GB of RAM?", especially when ARM code is

relatively compact.

   First, the compactness of code has almost nothing to do with RAM usage.

Most RAM is used by the data an application is processing, not the code of

the application.

   There are many reasons why 1GB+ of RAM is needed, although certainly

everyone's milage will differ.

   Most Linux distros currently have stated memory requirements of around 1GB,

especially for non-command-line usage.

   Most PC's currently come with 4GB+ of RAM, and many applications are

taking advantage of that memory, including IDE's like Eclipse, word processors

such as LibreOffice, GUI's such as Gnome, multi-tabbed browsers, etc.

  Compiling large linux packages takes over 1GB, including webkit, gtk,

LibreOffice.  Some linux distros depend on packages being compiled

natively rather than cross compiled.

  RAM can be used for I/O buffers, and for ramdisk, to compensate for

slow disk access.  The RPi forum is hosted on a machine with 96GB

of ram for that purpose.

p.s.

  8Gb lpddr2 memory chips appear to be available today, although

not certain at what price, quantity, and form factor.

see http://sunrisenanotech.com/products06f.html

       http://www.dramexchange.com

You shouldn't host a popular website and forum on a raspberry pi.

The forum on raspberrypi.org is moving to phpbb instead of the wordpress thingy. Why? PHPBB is written more efficiently so that it will be able to handle increasing traffic.

Writing reasonably efficient code will allow you to do things with your 'pi that it was made for. You'll have to buy a bigger machine to do bigger things.

The fact that chips are listed does not mean that they are available. They often make nice pages advertizing new products cleverly hiding the fact that they are not available until 3Q2012. They hope you'll design with their component and only then find out that you can't buy them in quantity. That said, no 8Gb, 168 ball, 1.8V DDR2 is listed in the page you mentioned. (I don't know how likely it is that they would be compatible if it were listed). On the other site, I could not find any specs to see if it might be compatible.

right, you shouldn't host a popular website on a RPi, but you might want

to host a less popular website, with 1GB+ of the most frequently accessed

pages cached in RAM.

It looks like the 8Gb, 168 ball, DDR2 part listed is 1.2V rather than 1.8V.

If you have that kind of high hitrate, you shouldn't use a Pi for it..

The RPi is perfectly suitable for a server, costs about 64 - 80 MB in memory, remaining is for applications, caching...  more than enough to do all kind of things

I usually use the filesystem for storing webdata, no database overhead and very fast access, most of the time everything is cached automaticly by the filesystem.

I hope that in feature version they will stick to the 256 MB.....

That will make/force people to make/find more efficient solutions/programs.

Hans

Hans,

  It may seem to you that the RPi was designed with a ridiculously small RAM

in order to "make/force people to make/find more efficient solutions/programs".

But that isn't the case. 

It was designed the way it is because it was repurposed from the Roku design

as an educational computer rather than a media center, with no easy way to

enlarge the PoP memory.  As opportunities for enlarging the memory become

readily available, I'm sure the RPi will take advantage of them, even beyond 4GB.

If the RPi designers actually subscribed to the "hair shirt theory of programming

excellence", they would have reduced the cost by using 128MB instead of 256MB,

or maybe even left off the PoP RAM completely and used the 128KB L2 cache for

program memory.  That would still have been much more memory than the BBC micro.

Hynix 4Gb (=512MB) PoP RAM is now in mass production.

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

previously this page showed the status as "customer samples".

Did you end up trying your DS1338 RTC board with with Pi? 

It looks like it can operate at 3.3V so no level conversion is needed.  I've hooked up the DS1307 RTC with bootc.net's Linux 3.2 image and it worked well.  But I'm interested to switch to 3.3V part so avoid the wiring mess.

Drew, I didn't even realize that Element 14 had their own blog system until you posted this, and that people were replicating RPF's blog posts to it.

That could be very useful, since it allows commentary without their petty censorship, and it overcomes the Foundation's continued attachment to Wordpress which has always made navigating their blog a pain.

Drew, I didn't even realize that Element 14 had their own blog system until you posted this, and that people were replicating RPF's blog posts to it.

That could be very useful, since it allows commentary without their petty censorship, and it overcomes the Foundation's continued attachment to Wordpress which has always made navigating their blog a pain.

Yikes, I've read about IP address bans and just realized that might mean a user wouldn't be able to even read the RaspberryPi.org blog, is that right?

In general, I'd love to see more members of this group post in the group's blog about any Pi projects/tinkering they might be doing.  I'm going to post about another I2C device shortly.