Raspberry Pi PCB Layout Revealed

An anonymous reader writes "Yesterday, the final Raspberry Pi printed circuit board (PCB) layout was revealed. The word 'packed' comes to mind as this is one very complicated looking board. The reason for that is just how much Raspberry Pi has strived to save money on the machine by using complex routing to keep things small and cheap. The Raspberry Pi team don't believe the design is going to change again unless they missed something. With that in mind, they revealed the final board is exactly the same size as a credit card, measuring 85.65 x 53.98mm."

Comments

Screen and keyboard?

[lordmetroid]

How am I going to use this computer without a screen and keyboard?
I demand a credit card sized keyboard and screen!

Re:Screen and keyboard?

[vlm]

How am I going to use this computer without a screen and keyboard?

I demand a credit card sized keyboard and screen!

Thats called a "cell phone"

Re:Screen and keyboard?

[Baloroth]

Is that a "whooosh" I hear?

Re:Screen and keyboard?

[ColdWetDog]

Is that a "whooosh" I hear?

He's probably on AT&T - he won't hear anything.

Features?

[Anonymous Coward]

What type of ARM processor does it feature?

Re:Features?

[afidel]

ARM11, specifically ARM1176JZF-S 700-megahertz which is a component of the Broadcom BCM2835 SoC.

While it's cool that they got the cost so low I'm kind of sad to see all those SMC's, kids today can't get into building electronics because so much stuff has gone to stuff that you just can't solder by hand. Yes, I know you can still use microcontrollers with breadboards, which is cool if you want to make a simple robot, but stuff like building your own computer that you can hook up to your TV and use like any other computer would be very cool as well.

Re:Features?

[WorBlux]

RTFA: BCM2835

Re:Features?

[QuasiSteve]

While it's cool that they got the cost so low I'm kind of sad to see all those SMC's, kids today can't get into building electronics because so much stuff has gone to stuff that you just can't solder by hand.

While I'm with you on this on many levels (remember building things with the 4000 series? Yeah, we don't do that anymore. Haven't since PICs. We just write some code that does the job much better), I wouldn't say that kids can't get into it anymore.

SparkFun, for example, regularly organizes PTH and SMD soldering classes as well as offering kits for both. Some SMD you can solder by hand quite easily, others you can get a nifty breakout board that lets you easily seat the SMD IC and melt solder up to its leads ( http://www.youtube.com/watch?v=-32orELxkpE ), and yet others you get some solder paste, a syringe or a toothpick (seems popular), put the paste on the pads or dip the leads in the paste, put the part on the PCB, and then stick it all into your toaster oven.. or on a skillet.

Of course for most kids, just playing with e.g. Arduino and some shields/sensors is going to be a great way to get into electronics in the first place.. then when they need something that's not on the market they can explore PCB design, soldering, etc.

Re:Features?

[tlhIngan]

While I'm with you on this on many levels (remember building things with the 4000 series? Yeah, we don't do that anymore.

Why not? The CMOS 4000 series and TTL 74xx series is still around, even in the various combinations (74HCxx CMOS, 74HS, etc). They're still availble from Digikey and the like, and many designs actually use them still.

Re:Features?

[NixieBunny]

That's what Arduino shields are for.

It would be rather difficult to make any GHz computer board these days using parts that a person could solder by hand. That's the price we pay for having $100 GHz computers.

Re:Features?

[inflex]

Really, SMD is not hard to solder, you just use different techniques with your old tools.

Sure, BGA is out of the picture for most people, but SOIC, TQFP, SSOP/MSSOP and parts down to 0402 are still hand-solderable. You just have to make the mental shift away from thinking "OMGZ, It's surface mount, I'll never be able to solder that!". In many ways SMD is a lot easier and simpler, because surface tension becomes your friend.

Of course, failing that, go get a skillet and some solder-paste or convert a pizza oven into a reflow chamber. I for one am happy to never deal with pin-through again.

Re:Features?

[Grog6]

All the originals are still available from somewhere, lol.

The new families of chips are smt, but you can do those with a syringe of solder paste and a heat gun. :)

It works for most stuff except for bgas.

It take a bit of practice to get just right; I started practicing on smt stuff in '86. iavo, lol.

Re:Features?

[Bluecobra]

I agree, I wish there was a kit I could buy to build a functional computer that could run a modern Linux distro. I know that they make a kit called "Replica 1" that you can build an Apple I clone, but I wonder if there is something out there more advanced. I was thinking how awesome it would be to assemble something like a Raspberry Pi and put it into a case with a similar formfactor as a ZX Spectrum.

Re:Features?

[mangu]

Why not?

Because, except for hobby or training, it doesn't make sense.

There was a time when one used lots of 555 chips. Today you have the 12F675 PIC in the same eight pin format that can do almost everything the 555 can do without any external components. A 12F675 cost about $1.60, which is $1 over the price of a 555, but the lack of external components and the added flexibility will compensate for that.

The same can be said of most discrete logic chips. Unless it's a very simple logic function, it makes more sense to use a PIC than to assemble a circuit from TTL or CMOS chips.

Re:Features?

[cnaumann]

It is also worth mentioning that there are many PCB manufactures and assembly houses that will make a couple of PC boards for you and install all the BGAs DQN, FQN, and power pad packages for you for just a few hundred dollars.

Re:Features?

[QuasiSteve]

Well I pretty much gave the reason just slightly further down that paragraph; a microcontroller, be that PIC or AVR or whatever one prefers, will do the job much better. However, I should have added "in general".

Yes, the 4000 and 74xx series are still produced and actively used in design. However, check which ones, and why.
A BCD-to-7-segment decoder, for example, makes sense to use simply because they are readily available, cheap, and driving a 7-segment from your microcontroller is a waste of pins and raises power ratings concerns... an alternative is getting a specialized microcontroller that has a 7-segment driver on board.. which of course is more expensive.

But if you look at, say, a serial in parallel out, or a counter, or.. etc. If your design already uses a microcontroller, then adding their functionality in code is much simpler and more flexible. Unless you're running out of memory space, it's the way to go.

I still do 4000 series designs (and specifically the 4000 series as it's more forgiving of mistakes), but only for the specific purpose of teaching kids the basic principles of their function, how to interface them with each other, etc. But in the end, we then go to how we can duplicate each component's functionality in code functions, how those functions can interface with each other, how to streamline them, and get the same result from, say, a 16-pin PIC that the larger board with 12 8-pin to 18-pin + side-components did.

Re:Features?

[bsane]

I'll second that- I shudder when some part has to be through hole. It makes routing harder, and soldering is a bigger pain too.

Re:Features?

[petermgreen]

many designs actually use them still.

Oh many designs use one or two of them to glue stuff together but other than a few masochists noone builds large systems out of them anymore. The world has moved on, micrcontrollers for the non speed critical stuff, programable logic for the speed critical stuff.

Re:Features?

[inflex]

About the only time I'm appreciative of PT on a board is if I'm trying to route a power rail and I can use the leg/pin as an implied via, but overall, yep... PT is a PITA. :D (not to mention how it slows up assembly so much!)

Amazing

[Anonymous Coward]

This will make for a great HTPC, assuming it can decode video. Anyone know what type of video out it supports? I just saw, "hook to your tv."

Re:Amazing

[ZeroSumHappiness]

1080p30 using h.264 is the top specification.

Re:Amazing

[dreemernj]

They demoed it running 1080p video smoothly at a tech show. I don't remember the specs, but, for the price and size, I remember being impressed.

Re:Amazing

[JDG1980]

The real question is whether the underlying APIs will be open to the public, or if you'll have to sign some sort of Broadcom NDA to actually use the features the hardware already contains. Also, I'm interested to know if HDMI 1.3 bitstreaming (TrueHD and DTS-HD) is incorporated. These shouldn't require any licenses since the data isn't being decoded, just packetized and sent over a cable.

*If* the APIs are open, this could be a great XBMC platform with full support for all the Blu-ray codecs.

Re:Amazing

[DrXym]

Most of these chips support in hardware the stuff your average blu ray player or satellite box has to support. But support doesn't mean make available. There are so many patents around these things that the tech is usally masked off and you have to load a token onto the chip at the factory to enable it. So the chip might be capable of a lot of things but you ain't going to be able to use them. I assume h264 is going to be enabled by a token but it would still need the APIs in order to make use of it in hardware. And that would raise some interesting questions about what happens if you invoke those APIs from GPL software, and aside from that how do you go about overlaying graphics over the video buffer while it is playing out.

Re:Amazing

[JDG1980]

I don't see why there would be any GPL issues. The patent license fees were already paid by the hardware manufacturer, and all the GPL software is doing is sending it a bitstream. What happens to the bitstream after that has nothing to do with the software license.

It would be absurd if there were hardware features of the chipset that could not be used due to being deliberately disabled. For the Raspberry Pi to be workable in a HTPC or media streamer setup, it must support at least VC-1 and MPEG-2 bitstream decoding in addition to H.264. Although they are less intensive to handle in software, I doubt the Raspberry Pi's weak (by modern standards) ARM CPU can handle 1080p23.976 decoding of these formats via software alone.

Re:Amazing

[DrXym]

My first point was that if Broadcom were to provide a proprietary SDK to access the h264 functionality, would a GPL application such as XBMC be able to link to and use those apis? It's a licencing issue. Would Broadcom even release the APIs at all except to specific licencees?

The second point is just a digression into how SoCs work. If you look through a chip's specsheet it will claim to support various techs in hardware. But to use them the chip must be loaded with a cryptographic token which unlocks the feature. Normally the STB manufacturer would buy the tokens and load them onto the box in the factory. No token = no access to the feature. So I expect Raspberry Pi will support h264 and HDMI because it's publicly said as much but there is no guarantee it will support other things the chip have the potential to do.

The third was just a throwaway comment but ties into XBMC again. These SoCs usually split the display into layers, e.g. 1 or 2 presentation layers, a subtitles layer, a video layer. So even if you could hardware accelerate the video playback, it would have to tie into the way XBMC or other media players composite their screen. I expect XBMC would probably just use a null video driver and would rely on the APIs to fill in the video layer. Perhaps it might even keep the video playback / trickplay functionality in a separate process to keep itself and the proprietary APIs separate from each other.

Complicated?

[thoughtspace]

Huh? What's complicated about that board? Looks pretty normal.

Re:Complicated?

[Austerity Empowers]

I would go as far as to say that looks like one of the simplest and least complicated designs I've seen. Also it should be noted that small and cheap compete with one another. Cheap things they that cost space- fewer routing layers (components & traces often need to be farther apart for impedance & via room), using larger components (0402 or bigger generally), not using blind/buried vias, using routing space for power. Small things they did that added cost- front/back side assembly, through hole components on a mostly SM design.

It looks like a fairly simple design. I'd try to get rid of the through-hole stuff unless it's just debug, that adds a step in mfg which can raise cost and also causes place keepouts to eat up valuable real-estate.

The post should have raid "Board layout review, all slashdotters attend".

Re:Complicated?

[mla_anderson]

Actually looks pretty slack with lots of space. However to make it inexpensive requires much more care in the design rules and routing. Placing and routing a board with tight component clearances and tight trace and space is easy and expensive. Taking the same components on a small board from 0.1/0.1mm trace and space to 0.15/0.15mm trace and space takes a lot of work, but can significantly reduce the cost to manufacture.

From an initial view, the biggest cost adder I see is components on the solder side. There don't seem to be too many on the bottom side and with a bit more work it could probably be made into a single sided board. I'm working on a cost sensitive board right now, and one of the big things we've done to cut cost is make sure all components are on the top side. (Low cost is relative, this BOM is many many times the projected price of the R-Pi.)

Re:Complicated?

[ebenupton]

Would be great to get all the components on the top side. Unfortunately, you pay for that in extra track length between the SoC decoupling caps and the BGA balls. I believe Beagle and Panda both do this with their OMAPs, and (mostly) get away with it, and we may investigate it in a later revision; in general departing from datasheet recommendations makes me queasy, even for a chip I worked on...

Re:Complicated?

[TheRaven64]

This machine is the spiritual successor to the BBC Micro. I have here the BBC Micro User Guide, which has hand-drawn circuit diagrams in the back. In comparison, this board is very complicated. In comparison to anything modern, it's pretty simple.

Re:Complicated?

[muon-catalyzed]

Except nobody noticed that it is just one extended socket for the massive proprietary Broadcom BCM2835 chip (SoC) that provides pretty much everything, so this is 90% Broadcom thing, the UK team just provides fancy packaging and folklore. Does anybody know the price point of that Broadcom silicon?

Re:Complicated?

[JDG1980]

The announced price is low enough that I don't really care how much the raw chip costs; for hobbyists, you're very unlikely to find a better deal.

What concerns me more is the "proprietary" aspect. How many of the chip's features will be accessible by hobbyist developers? Will we be receiving full public documentation on how it works?

Re:Complicated?

[rec9140]

"What concerns me more is the "proprietary" aspect. How many of the chip's features will be accessible by hobbyist developers? Will we be receiving full public documentation on how it works?"

No, getting data sheets from most silicon makers today, is tanamount to asking for state secrets,err...ok not such a good example, well not hapenning... and don't mention to the Pi people.

See:

http://www.raspberrypi.org/forum?mingleforumaction=viewtopic&t=1077

Re:Complicated?

[kmahan]

Did they length match any of those pairs? It'd be interesting to see a trace length report.

Re:Complicated?

[mirix]

It doesn't really matter what the chip costs alone, as you won't even get a fucking pin diagram out of broadcom without a large order and an NDA.

Re:Complicated?

[mla_anderson]

Generally if the small caps are close to the package and tied to planes (I'm assuming there are planes) with short thick ties to reduce inductance you can get by with it just fine. The bulk caps can be quite a ways away as long as they are also tied directly to the planes. We're running some very high speed stuff this way without problems. Xilinx has some good info on bypass caps and how they can be placed in their Spartan 6 docs.

If there's no planes then you have to have the relatively thick tracks already for current carrying capability, but the inherent inductance could possible give you an edge in filtering as long as you're not yanking the individual pin levels out of tolerance.

Re:Complicated?

[mla_anderson]

No, getting data sheets from most silicon makers today, is tanamount to asking for state secrets,err...ok not such a good example.

And asking for answers from Broadcom if you're not buying millions of their chips is likely to get you shot for treason.

Re:Complicated?

[Inigo Montoya]

Yeah I'm pretty bummed that they chose Broadcom. It's ARM, and there's plenty of vendors.

I'm just guessing, but perhaps another more "open" choice would have added $10 to the cost, and maybe they didn't want to go there, if their price target
was firm.

Re:Complicated?

[Savantissimo]

Yet other manufacturers don't take that attitude. Go look at TI or Analog devices. Full datasheets right there, often running to hundreds of pages reasonably priced development boards, often free samples. Broadcom claims to have features such as DSP and GPU built in to this chip, but I don't know what use they are supposed to be if they are totally undocumented. Supposedly about 98% of the FLOPS in this thing are in the GPU, but good luck getting at them.

Re:Complicated?

[Anonymous Coward]

Really, modded down...what was the motive behind that? Someone points out vaporware?

Re:Complicated?

[mollymoo]

I'm guessing they went with Broadcom because at least one of the Pi team works for Broadcom.

Re:Complicated?

[BeaverCleaver]

I may be feeding a troll here, but they're not taking money until they have a product to ship. They're not taking pre-orders either. So nobody is trying to scam money for vapourware here.

Re:Complicated?

[Anonymous Coward]

It would also be great it they had mounting holes.

Re:Complicated?

[PeterBrett]

Xilinx has some good info on bypass caps and how they can be placed in their Spartan 6 docs.

Xilinx Application Note 623 is an excellent introductory guide to PDS design.

Just to expand on your points: the main thing to bear in mind is that the higher the frequency you're running it, the smaller the cap values you need and the more important it is to keep loop inductance low. There are two cases in which I place my decoupling caps on the reverse side inside the package footprint (usually BGAs have an area free of pins in the centre of the die). Firstly, when I'm running at very high frequencies (> 100 MHz) and it's essential to use really tiny capacitors. Secondly, when I have a very restricted number of layers and putting the caps inside the footprint simplifies my fanout.

Re:Complicated?

[Anonymous Coward]

Atmel is pretty good about full datasheets, too; that's probably one of the reasons the Arduino people went with them. I'm not a big fan of Broadcom either.

Re:Complicated?

[doogledog]

Although TI are a lot more forthcoming with datasheets they will still hold back information on things like the DSP core inside an ARM SoC. So you get DSP based codecs as binary blobs and no information on how to target the DSP yourself. And then further up, in the same family, you'll get a similar processor that *does* have an accessible DSP core... but you have to pay for the privilege in chip cost (and it only makes sense to do that if you actually need that feature).
Then again, as you said, TI are good at letting you buy small amounts of these chips as well as devkits so it makes sense for most of the information about the chip to be accessible. There's no chance of going to Farnell and buying one of these Broadcom processors.

Re:Complicated?

[Anonymous Coward]

They did mention* that they choose this chip because of the specific features at a cheap enough price. I don't much like the closed aspect of the Broadcom chip myself, but I doubt I'll be hacking the hardware anyway and it is cheap enough to consider disposable (not that I like chucking perfectly good stuff away) if the binary blobs required by the drivers block software updates.

And there is also a link with one of their team and Broadcom, but mollymoo is wrong, he is an former employee rather than a current one. How much that had an effect on their choice, well I don't know.

*Somewhere on their site, but I think it may have been in the comments to one of their announcements.

Re:Complicated?

[Anonymous Coward]

And there is also a link with one of their team and Broadcom, but mollymoo is wrong, he is an former employee rather than a current one. How much that had an effect on their choice, well I don't know.

Ignore this. I'm an idiot. After posting this comment I was reading through the thread in the Raspberry Pi forums, and apparently there are members of the team the do work for Broadcom, though I don't know if they maybe came on board after the original members picked the chip or if they were there from the start. Sorry to mollymoo for saying she was wrong.

complex routing ?

[alvieboy]

At first glance, this looks like a normal routing with a 4-layer board. Eventually 6, if you add proper ground + power.

There's nothing indicative of PCB parameters, like drill sizes, clearances, blind/buried vias, minimum trace width, so on. Again, a simple look reveals nothing but common parameters for PCB.

Again, TFA is biased.

Re:complex routing ?

[Maddog Batty]

I'm with you on this. It looks to me that someone took time and care over it to keep the tracking to a minimum but not anything special. I have a draw full of PCBs which are similar and I don't claim to be particularly good at PCB design.

Re:complex routing ?

[Gazoogleheimer]

Yeah, nothing to see here (coming from someone who essentially designed an ARM Linux system-on-board with similar performance for an entirely unrelated application)...ordinary and almost reminiscent of reference designs. The CraneBoard is much more complex.

Re:complex routing ?

[DeadCatX2]

Looks pretty pedestrian to me (although a BGA breakout on so few layers is worth a tip-of-the-hat). I think I only see three signal layers; blue, yellow, and reddish-brown. So they probably have a proper ground plane that's being excluded from the pic. The big swaths of yellow might be a power bus.

Now with only one solid plane, one of the other three layers will not have a solid reference plane. Did the designer take time to make sure no high-speed signals run on that layer? If not, then I expect a noise and EMI nightmare from this board.

Re:complex routing ?

[ebenupton]

As I understand it, the biggest challenge was escaping a 0.65mm BGA without using significant amounts of HDI on a 6-layer board, while keeping good solid power and ground planes and large (i.e. cheap) track and gap specs. Relax more or more of those and it is indeed trivial - our alpha boards were done in about four days by doing exactly that.

Re:complex routing ?

[Imbrondir]

Out of curiosity, how much more expensive would smaller track and gap specs be for similar volume? No need for an exact number

Re:complex routing ?

[ebenupton]

Off the top of my head, we save around a buck at 10K-off through a combination of 6 layer, coarser T&G and limited HDI. Figures for UK manufacture; YMMV in elsewhere, particularly in the far east (where cutting edge volume manufacturing is much easier).

The particular stack-up we've chosen is only one possible cost minimum; I've heard it suggested that 8 layers with zero HDI is quite competitive for 0.65mm BGA.

Re:complex routing ?

[dotbot]

Looks pretty pedestrian to me (although a BGA breakout on so few layers is worth a tip-of-the-hat). I think I only see three signal layers; blue, yellow, and reddish-brown.

Is blue really a signal layer? Looks like blue and pink are silks to me and the board is simply double-sided.

Re:complex routing ?

[artor3]

I don't know know what you're looking at, but it's pretty clear to me that this is a 2-layer board, unless you're counting silkscreens as layers, which would be really weird.

Re:complex routing ?

[mla_anderson]

Another cost is wastage. As trace and space get toward the manufacturer's minimum recommended numbers their yield goes down and therefore their price goes up.

Re:complex routing ?

[DeadCatX2]

Wow, that's embarrassing that I didn't notice the backwards designators written in blue.

Re:complex routing ?

[Anonymous Coward]

Slashdot is full of bias. Ever take a look at any thread relating to "3D printing"?

Re:complex routing ?

[Anonymous Coward]

it's a six layer board. They left out ground and power.

Also that size...

[X86Daddy]

Penguins and Altoids tins happen to be about that size as well... I wonder how well a populated Pi will fit... if so, awesome little PC cases!

Re:Also that size...

[Anonymous Coward]

Can't wait to cut tiny holes in the side of the tin and add lexan and blue LEDS and maybe even a case fan!

ALTOIDS EXXXTREME

Re:Also that size...

[Anonymous Coward]

Seems it would almost fit a normal pack of 20 filter cigarettes as well, but only almost; a few millimeters too long.

It's a nice size, custom cases for custom uses could be fun (somewhat "softbodied" plastic sheet cases comes to mind as a possibility and would be ultra cheap).

Re:Repeat much?

[Anonymous Coward]

I'm fine with this. R-Pi is worth it.

This could make a pretty big change for computing hardware and software learning.
Too much is done on overbloated hardware where you aren't even exposed to said hardware.
Most people in computing don't even understand the very basics of yester-2-decades-agos knowledge.
The most they touch on it sometimes is throwing together things in Java, if they are lucky.

It's all fine and well if you can do X on a really powerful computer, but being forced to do it and have noticeable slowdown or inefficiency in code by not doing it is a HUGE difference.
Having limits forced on to you in order to design efficient code is the best way to design said code.
But most developers these days are absolutely atrocious at their work, abusing the hell out of hard drives, flooding your RAM and page files with crap all over the place because they feel that their program has more worth than another persons program.
Worse when they do all that AND LAG LIKE HELL. (STEAM! DAMN IT VALVE FIX THAT CRAP ALREADY)
PEOPLE. MULTITASK.

I'm hopeful for the next generation of developers actually having an education on this, as well as possibly other similar boards. (admittedly a little on the expensive side in comparison)
So many lost techniques with all this high-level abstracted knowledge.
It's like building the frame of a car without the body. Sure, people could push it, people could pull it, hell, they could roll it down a hill. Still doesn't work efficiently.

Not so packed

[dpaton.net]

Really, it's not. I do stuff like this every day. It looks pretty normal for a 4-6 layer board with a BGA or two on it. TFA needs to learn about what modern design standards are. It's only complicated if you still lay boards out with ruby tape or a sharpie.

Re:Not so packed

[Beorytis]

I think they meant to say: "It's really complicated compared to the average DIY Arduino shield with DIP sockets on it."

Re:Not so packed

[inflex]

The trouble with this sort of reporting is that it betrays the work done daily by people who really -are- dealing with complicated stuff. Reminds me of parents rabbling on about their "genius child" because the kid installs software O_o.

Re:Not so packed

[PeterBrett]

It's a pretty trivial board. I'd quote at most a day's work (8-10 hours) for a board of that complexity, even assuming I was handrouting the whole thing...

Re:Not so packed

[BitZtream]

Yes, compared to something about 3 orders of magnitude less complex, this seems complex.

However, I do 4 layer boards with the bigger AVRs and boards produced by BatchPCB 2 or 3 times a year. Its not really complex. I admit, I've not done BGA layouts, but with multiple layers I can't imagine it'd be THAT hard. Tedious to do by hand, certainly, but with software, meh, not much different than an excel spreadsheet really.

what is it for?

[Anonymous Coward]

Maybe I'm just not the target market, but I don't get it. What is it for?
Can someone who wants one explain what you will do with it?

Re:what is it for?

[JDG1980]

Well, it can run Linux, so I suppose you could use it as an ultra-cheap nettop for someone who just does web browsing and email.

It could make a good XBMC platform assuming they open up the APIs for HD video stream decoding.

It could also be useful for embedded system applications for which an Arduino or similar device is not powerful enough.

Re:what is it for?

[Yvan256]

Three words: Tiny, low-cost, MAME.

Re:what is it for?

[slim]

Give it to a child, plug it into a TV or monitor and a keyboard, and you allow them to be creative.

The software side of things will be intended to push that side of things.

Think OLPC, only not so squarely aimed at the developing world, and assuming that people can source screens and keyboards separately.

Sweet. My dream Halloween costume comes closer.

[Commontwist]

If I could ever easily design a non-expensive Sci-Fi armor suit that has redundant, networked computers, streaming video-to-internet from a helmet, real-time video display in helmet, easily detachable web cam/mic/speaker modules that can be used on or off armor, and able to be worn from -50C to +50C I would build it for my Halloween costume and stream visiting Halloween parties to a web page. Reusable for comic and anime cons too. Heh.

Re:Repeat much?

[TheRaven64]

Slashdot has become an RSS feed for the Raspberry Pi blog

Yes, how dare a site that claims to be 'news of nerds' cover a project to build a cheap computer designed to be interesting for school-aged nerds to play with? I demand more Apple stories, and political news!

What a wonderful project!

[Hobart]

...and yet, just like the OpenMoko FreeRunner (giant opaque SMedia Glamo blob meant 2d VESA grade graphics only) and the OLPC XO-1 (giant opaque Marvell blob meant the whole WiFi subsystem and "mesh-while asleep" was all a black box and driver couldn't be troubleshot) , all the software is "open" yet obfuscated

The entire Raspberry Pi depends on a gigantic proprietary blob from Broadcom.

Hmm. Google search came up with this deviantart for "Raspberry Blob", maybe this can be the project's mascot. Hooray for undocumented blobs, we don't need source code, maybe we'll get Windows CE for it someday!

Re:What a wonderful project!

[Jamie Lokier]

all the software is "open" yet obfuscated

The entire Raspberry Pi depends on a gigantic proprietary blob from Broadcom.

So let's do a Nouveau-style reverse engineering project. How hard can it be?

Sounds like a perfect project for the target audience: curious and talented kids. With a bit of experienced help if they get stuck (seems unlikely to me though, with sufficient time & motivation). Some kids love reverse engineering. I did when I was young and I was far from the only one (but we didn't have an internet to meet each other back then).

(I did loads of reverse engineering from about age 11+ (that was 1983), starting with the BBC and moving on to everything I could get access to, pulling apart games (starting from the binaries), changing behaviours, porting them from tape to floppy disk ;-), even porting them to new architectures, and now I think about it, quite a lot of hacking on video hardware of the time, both in hardware, and quirky programming to make it do useful things it wasn't designed to do. If Mr Braben is listening, I printed a whole disassembly of Elite, BBC disk version on dot matrix that took days to print (wow just got a flashback), and spent a long time learning from its algorithms, some of which I still use today - thank you ;-) )

Re:What a wonderful project!

[iluvcapra]

Elite ran in 14k of memory (which should have been enough for anybody, wokka wokka). This blob is 16 megs. That's a 1,170 11-year-olds; if they went about it with your methodology, they'd be printing out one disassembled line a second for about twelve weeks... And then they gotta figure out what it DOES. And all of this before Raspberry Pi changes CPU revs and the disassembling must start all over.

Re:What a wonderful project!

[Anonymous Coward]

Have you complained to NVidia lately that they don't open-source their firmwares?

Yes, I have. I run Nouveau. And black-box PROMs are just as bad. Next question?

Re:What a wonderful project!

[Anonymous Coward]

Nouveau is the driver, not the firmware. The firmware is closed source software, but as I predicted, you don't know or care because it's stored on the card, not where you can see it.

Re:What a wonderful project!

[mirix]

I had a lot of hope for this, and was willing to accept a binary blob on the GPU, for the price. Don't think I'll need video anyway.

But having to load a binary blob on the GPU in order to load a (bootloader | kernel)? Yuck.
I guess that's better than the driver though, in a way, as it shouldn't be kernel dependent, like a closed BIOS on a motherboard... So you don't have to worry about not being able to run the board with linux-5.8 as that is neither here nor there. (at least, this [booting] portion. You'll still have binary blob video driver hell).

Re:What a wonderful project!

[Jamie Lokier]

The bit about my own history was just to illustrate that young people (the target audience for RP apparently) do take an interest in that sort of thing, not to suggest a method! Of course nobody would use that approach any more! (The Elite reference was because David Braben co-authored Elite and is also involved in RP).

If analysing the blob statically, and if you know the instruction architecture, we have much better tools now, including disassemblers, decompilers, type inference and much more. And internet so we can collaborate better.

16MB is a big blob, but it's highly unlikely that much of it is needed to make a useful open source subset of the functionality.

For perspective on speed: Recently I had to reverse engineer about half of a 1.5MB ARM driver blob in some detail, enough to fix bugs and improve performance deep within it. I'm not going to say what it was, only that it took me about 2 weeks with objdump and some scripts, not using more advanced tools. I didn't enjoy it because it was just to fix some bugs the manufacturer left in :-/ (The best bit was a one-bit change that tripled video playback performance and stopped it stuttering :roll-eyes:)

But there may be a big fat license prohibiting anyone from openly using the results of that type of deep code analysis on the RP's blob.

Plus, there's the secret GPU/RISC architecture to get to grips with; that's not going to be obvious.

So it would probably have to be Nouveau-style: Run the original, watch its interactions with the device (with tracing probes), replay things, change things randomly, try things, gradually build up a picture through guessing as much as anything. That's a much bigger task than statically analysing a blob's code. (At least, to me it seems so.) I don't know whether it's practical on the RP, and I don't know whether it's too difficult. But it worked with Nouveau - and that now supports a lot of nVidia chips - so not to be dismissed as impossible.

You never start all over after a chip rev. That's why they call them revs, not new architectures. You can diff code in blobs if need be; often the changes for a chip rev are very small.

You may be right about needing a lot of 11-year-olds (or others). Luckily the RP is cheap and interesting enough, that it might attract enough interest.

The suggestion isn't all that serious, but nor is it an impossible task, so I think it's worth floating the idea around, see how much interest there is in at least looking further at the practicalities and legalities.

Re:What a wonderful project!

[Anonymous Coward]

More info on this:
http://www.raspberrypi.org/forum?mingleforumaction=viewtopic&t=1018

Re:What a wonderful project!

[BitZtream]

You''re upset because you have to load a 'binary blob' at boot ...

Yet you're too stupid to realize that the chip itself contains several embedded 'binary blobs' that it uses to get to that boot loader.

You're basically bitching about something that happens in every microprocessor on the planet, the only difference being that you have to help out in this one, where as say a pentium chip has the blob built in.

Same is true for video drivers. You Linux/GPL zealots get so fucking worked up up about binary blobs, yet your too stupid to realize you've been depending on them since day one, that is, unless you can show me the open source masks intel uses for its chip lithography.

If the blob was embedded in the chip, you'd be okay with it, but since its not, you get your panties in a twist. Ignorance is bliss isn;t it.

Re:What a wonderful project!

[Anonymous Coward]

BitZtream (you arrogant fuck),

People are just as concerned about CPU microcode. http://www.interesting-people.org/archives/interesting-people/200407/msg00251.html

Also, OpenBSD zealots are just as worked up as Linux/GPL ones over said blobs.

Please die in a fire.

Embiggen...

[linatux]

a perfectly cromulent word

Re:Repeat much?

[Toonol]

Thereby improving the quality of Slashdot. It at least guarantees an occasional techie story.

XBMC

[Anonymous Coward]

XBMC is working on a port. That could make a big difference.

I personally would like emulators.

Re:Repeat much?

[kiwimate]

Y'know...being candid, I'm barely interested in Raspberry Pi at all...but this is definitely of note for the target audience for Slashdot, or what Slashdot used to be in the late 90s when I first started reading it. Much better than some of the really worthless ask slashdot questions that get through, for instance.

Re:Repeat much?

[JoeMerchant]

I'm getting to be on the fence about this - maybe one Raspberry Pi story a week would be enough (same for any other nerd-worthy topics), what's the point of editors if they just re-post everything that comes their way? Heck, they even posted one of my submissions recently.

How can you even tell?

[artor3]

Is there a layer-by-layer break out some place? The way they have all the layers on top of each other in the PNG makes it very hard to tell what's going on in the red-colored layer. The yellow layer at least looks pretty simple, though the fact that the QFN's epad doesn't appear to be grounded strikes me as a bit questionable. A lot of IC's rely on downbonds to ground internal pads. Leaving them floating is a big no-no. While they'll probably find alternate paths to ground, they're not the sort of paths you want to rely on.

I can say from the photo in their forum that the through-hole stuff is indeed debug, unless they actually plan on having a 5x2 header on the final release, which would be pretty pathetic and lead to lots of accidental finger-stabbings. They have plenty of empty space once you move away from the IC footprints, so having some non-populated headers won't cost them anything.

Re:How can you even tell?

[Savantissimo]

Most of those questions are answered in the comment thread on the article. No individual layers released until their PCB designer gets back. The picture shown does not include power or ground planes, so the missing ground is likely hidden. The connectors being used will require some through-hole components. The GPIO headers will be on the final release, but unpopulated.

The biggest omission to my mind is the lack of mounting holes or other fixtures. (I'm not sure where you see "plenty of empty space". Even getting screw holes to fit would require some thought, it seems to me.) The screenshot was also pretty useless for determining the exact mechanical placement and dimensions of the connectors, which is the only important thing for those designing cases. Someone in the comment thread did mark and label the rough outlines of the connectors, though. The connector placement also seems not at all designed for usability, or with any thought to future case design but purely to make the cheapest possible board.

What's in a Master Card?

[Ostracus]

With that in mind, they revealed the final board is exactly the same size as a credit card, measuring 85.65 x 53.98mm."

And it's name will be Selma

Gum stick?

[Anonymous Coward]

So they've totally abandoned the original gum-stick form factor? Shame that's what bought them all the initial publicity. (More than the price point.)

Re:Repeat much?

[tchuladdiass]

I think the biggest thing that can come out of this project (especially if more like it come around) is the fact that the hardware is too cheap to run a non-free OS on it. Now sure, to make it into a full computer you have to add a monitor, keyboard, mouse, USB hub, storage (not sure if it comes with flash built in or if it needs a SD card to boot from), and and Internet connection. But most people are going to see the $25 price (assuming something like this ever gets retail) and pick one up. The netbooks almost made this happen (since they were Linux only when they first came out -- until Microsoft cut a deal for Windows XP). Only thing is, would the typical user be using a Debian based (or similar) distro, or would they be using a version of Android?

The only thing I think that would make this more useful is if they added another, say, $30 or so to the price and added a calculator screen / keypad to it (and battery/charging circuitry). Since most high school kids need a $100 graphing calculator, one that transforms into full workstation when plugged into a monitor/keyboard would be great. Of course the schools probably would never allow the use of an "open" calculator on exams (but then again, most high school level exams only need a simple scientific calculator -- or a slide rule).

Re:Repeat much?

[mollymoo]

You talk as though the Pi is feeble. It's a staggeringly powerful computer. Better than a workstation of a few years ago or a supercomputer of a few decades ago. You know, the kinds of things they used to design jet aircraft, run accounts for multi-national corporations, invent nuclear weapons, plan space missions, develop models of the universe and stuff. We're just accustomed to almost unbelievably powerful computers.

If you want someone to learn how to code efficiently give them an 8-bit microcontroller, not a 32-bit one-point-something GHz CPU with hundreds of MB of RAM.

Re:Repeat much?

[Yvan256]

Pick up an AVR and code in C. Not even an ATmega, start with an ATtiny. And to push things even further, I would suggest the ATtiny85 instead of the ATtiny861.

Re:Repeat much?

[hairyfeet]

Oh please! How damned delusional and desparate for users do you have to be that you HONESTLY think people in the west are gonna rush out and by a cellphone GPU based hackers toy? Maybe, juuuust maybe, if you would actually give the people what they wanted instead of singing the hacker song while putting out updates that bork your drivers, and just FYI but EVERYONE ELSE has a hardware ABI and have had one for over a decade, might want to wake up and join the current century, then you might not have to pray for a device cheap enough people will take your shit?

I mean how fucking sad when your ONLY hope at this point is that China can crank out something so damned cheap that Windows won't fit. Oh BTW, just to REALLY ruin your day, but you know Windows 7 HP? Yeah its actually below free. you see they put this stuff called 'trialware" on the PC and the money they make from it actually is more than the cost of the OS. So unless you are gonna pay $20 to everyone to take your OS? you're only shot if you refuse to listen to your potential customers is to find shit with specs so damned crappy nothing else will run. Such lofty goals you got there Sparky, lofty goals!

As for the R-Pi? The only truly amazing thing IMHO is they are using a GPU as the main processor. look up the specs on that BCM and they make it clear its an HD decoder chip, no different from those HD mini PCIe cards you can put in a shitty low end Atom netbook to take a load off the craptastic CPU. I do find it amazing that someone would take a GPU and use it for a CPU, i've always wondered if one could do that. I bet the code is gonna have to be optimized up the butt to run worth a shit on such a highly specialized chip though.

But done right it could be a VIC20 or C64 for the third world, the only question is...will they care? they seem to be skipping a large part of our history, bypassing dialup and BBS and heading straight to low end smartphones and cellular networks. I have to question if this will even find a market in the third world when both India and China are racing each other to make the cheapest smartphone. I mean why bother with a blinking cursor when they can have Android loaded onto a nice pretty screen?

r4

[Anonymous Coward]

After reading your article, I’m compelling to share your points on this topic. You have done a very good job with your

attention to detail you put into this article.

Re:Repeat much?

[DrSkwid]

C, that's not even trying.

Step 1 : learn AVR assembler
Step 2: write a compiler / runtime / OS or whatever
Step 3 : ????? (debugging)

I asked Rick Perry about a step 4 but he couldn't remember one.

Re:Repeat much?

[Tsingi]

Oh please! How damned delusional and desparate for users do you have to be that you HONESTLY think people in the west are gonna rush out and by a cellphone GPU based hackers toy?

I'll buy 4. Maybe I'm delusional, but I could do a lot of cool stuff with one of these. Thinking of hooking one to a touchscreen and having it run my CNC.

I mean how fucking sad when your ONLY hope at this point is that China can crank out something so damned cheap that Windows won't fit.

Only hope of what? Windows is irrelevant to me, and whether or not you use Linux is irrelevant to me. I suspect it's irrelevant to most of the people who will develop solutions for these boards.

BTW, you sound bitter, I'm not sure what your point is though. These are awesome little boards targeted at innovators, you don't have to buy one. No one will mind. Or maybe you should buy one and put windows on it, show the world what an awesome OS it is.

Re:Repeat much?

[hairyfeet]

Did you even READ the post I was responding to? The guy was so desperate for Linux to gain ANY share he cooked up this scenario where a $25 cell phone GPU caused a "revolution" with people buying this en masse and tossing Windows! Nobody and I repeat NOBODY that uses a modern or even older Windows desktop/netbook/laptop is gonna shitcan their current setup for a $25 cell phone GPU that doesn't even come in a case!

You wanna know why Linux numbers are flatline? Its actually really simple, its because the developers and community won't listen and violate rule 1 of business, give the people what they want or at least what they think they want! Instead to paraphrase a line from Vietnam the whole thing has been taken over by deluded zealots that truly believe 'inside every user is a C programmer waiting to get out' like Suzy the checkout girl is reading Bash programming manuals in the bathtub and grandma is working on her CS degree in between knitting classes, its fucking nuts!

Look, if you want to be a hobbyist OS for programmers? I have NOTHING against that, in fact I ran OS/2 for years after everyone else had bailed. But coming up with one delusional scenario after another just makes your OS look like the property of the "Elvis is alive, NASA faked the moon landing" tinfoil hat wearing nutters. When I am having a conversation with a 15+ year Linux server admin who runs a giant server farm for a living and they tell me when i ask what distro to try as a final gasp before giving up and they say "As soon as I'm backed up i'm going to FreeBSD and if that doesn't cut the mustard I'm giving up on FOSS desktops and going Mac or Windows" you KNOW the shit is fucked up.

Fix the driver borkage (Protip: everyone else from BSD to Solaris has had a hardware ABI for nearly a decade, you think you are smarter than every OS designer on the planet?) and make an OS that will pass my "Is it safe?" test, where I simulate a user having the machine for 3 years by downloading the distro from 3 years ago and updating to current (which of course causes it to fall down like a house of cards) and then we'll talk. Keep predicting that some niche device will magically make people see bash prompts and programming as "the next big thing" and we'll all laugh at you and you'll stay flatline, kinda like...well right now actually. Kinda sad when MSFT puts out Vista, one of the most hated of their OSes EVAR, and you can't even gain a single percentage point. that is just sad man, totally sad and pathetic.

Re:Repeat much?

[Tsingi]

Did you even READ the post I was responding to? The guy was so desperate for Linux to gain ANY share he cooked up this scenario where a $25 cell phone GPU caused a "revolution" with people buying this en masse and tossing Windows! Nobody and I repeat NOBODY that uses a modern or even older Windows desktop/netbook/laptop is gonna shitcan their current setup for a $25 cell phone GPU that doesn't even come in a case!

Well, yeah, I did, I didn't get the same read on it. Or maybe I thought your post was a bit over the edge because I don't really care if anyone uses Linux as long as I can. Personally I don't feel the drive for everyone to use Linux. I do appreciate that it gets more development with more exposure, but basically UNIX is a developers toolkit, I'm a developer and I love Linux. Perhaps the original poster was a bit enthusiastic, but you went ballistic.

You wanna know why Linux numbers are flatline? Its actually really simple, its because the developers and community won't listen and violate rule 1 of business, give the people what they want or at least what they think they want! Instead to paraphrase a line from Vietnam the whole thing has been taken over by deluded zealots that truly believe 'inside every user is a C programmer waiting to get out' like Suzy the checkout girl is reading Bash programming manuals in the bathtub and grandma is working on her CS degree in between knitting classes, its fucking nuts!

The US accomplished everything they set out to in Vietnam.

Regarding the rest, I concur, I think that trying to make Linux a desktop for everyone basically cripples it. But I can run whatever distro I want, and they aren't all trying to do that.

Look, if you want to be a hobbyist OS for programmers? I have NOTHING against that, in fact I ran OS/2 for years after everyone else had bailed.

Regarding OS2, good for you! I never really did anything with it. I did set it up though. OTOH, hobbyists are perfect candidates for Linux. I have to disagree with you there.

But coming up with one delusional scenario after another just makes your OS look like the property of the "Elvis is alive, NASA faked the moon landing" tinfoil hat wearing nutters. When I am having a conversation with a 15+ year Linux server admin who runs a giant server farm for a living and they tell me when i ask what distro to try as a final gasp before giving up and they say "As soon as I'm backed up i'm going to FreeBSD and if that doesn't cut the mustard I'm giving up on FOSS desktops and going Mac or Windows" you KNOW the shit is fucked up.

Well, I built an ISP with Linux in '93, when it barely worked, and now it runs the internet. I still build my own server farms, although I'm not really a sysadmin. (OK, I built an ISP, but that was just to get on the net.) I'd have to say that your buddy must be a little slow, if he can't cut it with Linux, he probably should look for work in either the food service or hospitality industries.

Now, I build air traffic control systems with it. Avoid Heathrow, Sidney(+), Hong Kong, Dallas, Scandinavian countries, Dubai, and any Canadian airport because they all run our stuff. I'm Canadian and believe it or not, we win awards for this shit, we were on top three out of the last four years. Air Nav customers will not run Windows anymore, they all agree that it was basically a mistake to use it in the first place. It just doesn't cut it. Can't speak for hobbyists.

Fix the driver borkage (Protip: everyone else from BSD to Solaris has had a hardware ABI for nearly a decade, you think you are smarter than every OS designer on the planet?)

Me, no, but I'm up there. Then again, that isn't what you meant.

and make an OS that will pass my "Is it safe?" test, where I simulate a user having the machine for 3 years by downloading the distro from 3 year