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movax
Aug 30, 2008



This is going to own. Too much of the lower-level workings of modern systems (x86, etc) are being lost to NDAs and vaults in a handful of company basements.

For of those interested, they also released the reference file system that'll be shipping with the boards.

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movax
Aug 30, 2008



I still think the thread title is incredibly apt. I'm a baby goon, my family's first computer was a Packard Bell running a Pentium @ 75MHz. I kind cut my teeth on DOS, but there was still Win3.11 and other GUIs in place for me to use. I sure as hell didn't learn very much about PC hardware until later, when I tried throwing Linux on the box. I sure didn't pick up a real low-level understanding until my most recent job where I'm responsible for hardware design and maintaining a BIOS for a few platforms.

I think this board should do wonders in getting the next generation of engineers interested in STEM. A nice understanding of hardware/software at a young age should result in some very clever kids entering college. I think I learned more about CS loving around programming my TI-83 in middle school than I ever did from a formal CS class.

movax
Aug 30, 2008



DNova posted:

These poor guys can't catch a break: http://www.raspberrypi.org/archives/781

Hm, they must have used turn-key assembly or something for that to have happened. Otherwise, if they sent the factory kits of parts, it would be purely their fault in sending the wrong connector (or sending both types for some reason).

movax
Aug 30, 2008



Chuu posted:

Does anyone know exactly what these magnets do? I've been googleing trying to figure out electrically what is different but am failing.

Usually the Ethernet PHY has a magnetic isolation transformer (made by companies like Pulse, I guarantee you've seen a black rectangular slab of plastic with the Pulse logo on it) immediately behind the jack. This is for the four MDI pairs. Jacks with integral magnetics eliminate need for an external transformer which eats PCB space. Either way, the magnetics act to isolate the system from the Ethernet network, so ideally dangerous voltages/transients don't hose you, as well as improving EMI performance.

On a Pulse jack like the JW0-0006, the effective circuit is 1:1 isolation transformers (center-tapped to shield and ground respectively) followed by common-mode chokes (all inside the jack). ESD diodes are still generally discrete AFAIK.

Here is the datasheet for a common integrated-magnetic Pulse GigE jack, and here is a common discrete magnetic transformer you would need if your jack lacks magnetics. Pulse doesn't seem to make jacks without integrated magnetics and I'm a bit lazy to go find an example of one without magnetics to link its data sheet.

movax fucked around with this message at 22:36 on Mar 10, 2012

movax
Aug 30, 2008



Javid posted:

They really need to hire a grownup or two to supervise their decisions, at this point. I'm somewhat curious at what point a paying customer will actually have a working production board in hand.

Hell, just open-source the schematics (not even the artwork/Gerbers!) so people can get some boards made and assemble it themselves!

movax
Aug 30, 2008



DNova posted:

How are you going to obtain the CPU/GPU/RAM IC?

Avnet or Arrow NAC I'd imagine, whoever Broadcom's distributor is. None of the supply issues so far have been linked to lead times from Broadcom, have they?

movax
Aug 30, 2008



DNova posted:

No, but the RPi foundation had to work very hard to convince Broadcom to sell them such a small lot of 10,000.

Ahh, gotcha. Now I assume RPi foundation is going to be left footing the bill for getting CE testing done? I'm in the midst of CE tests at work right now as well, and the lab time is not cheap

movax
Aug 30, 2008



Mill Town posted:

Haha. The good news: not actually pushed back to August. The bad news: we actually have no loving clue when this will ship, and also is this a hole in the ground or my sphincter I can't tell http://www.element14.com/community/...-2012-questions

This is still really loving stupid, everyone involved knew (I hope so anyways) that the product would need to go through compliance testing. It'll take even longer to ship the board(s) if they can't pass, and changes will need to be made to get them to the pass (component or artwork) if necessary.

movax
Aug 30, 2008



nickdab posted:

I might lose my mind if this devolves into another gassed OS Wars thread.


That is actually a really interesting point. I think the RPi developers hope this will be a good gateway into programming for students, but most schools are just trying to get their kids to learn Word and Excel because that's what they will be doing for most of their lives. Maybe it will be the higher-income schools who have some extra money to waste? And parents who want their kids to learn programming for one reason or another, but don't want to risk their computers.

But I do think people are getting their panties way too bunched up waiting on a $35 machine from an academic group dedicated to helping children learn.

I think your thread title is a very apt description. The primary difference being of course, that when the Commodore 64 came out, it was around the same level of performance/features (I THINK) as its competitors. (I was not alive in 1982).

But, a lot of great programmers and engineers got their start playing with the C64. By necessity, you had to have a deep knowledge of the hardware. I would argue that regular desktop PCs, if available to a kid, still allow them to get a great start programming (so many beginner options out there).

The Raspberry Pi though is cheap (very low cost of entry to students), and it's not a big "deal" if you break it. A RPi will never be someone's primary productivity machine, or a shared family computer (I thought my parents would kill me when I screwed up my LILO config on the shared family PC). Again, one could argue that desktops/laptops have gotten cheap enough for families to have several in a household, but they are not $25-$50 cheap (unless it's a really, really old dumpster'd PC or something). It will do an incredible job of teaching though; the hardware isn't buried under a NDA, and since it is running Linux, if you find yourself needing to dig deeper...fire up LXR and start diving into the kernel issues. It may bring some development life back to the system instead of people pumping out JavaScript/etc web apps.

Despite the hardware being perfectly suited for it, I don't think people wanted a cheap XBMC-machine are the intended audience, nor do I think that their voices should have any input into the development of the board. I think the education aspect of the board should come first and foremost; getting a media player for $35 is just icing on the cake.

movax
Aug 30, 2008



spog posted:

I took at look at the last 5 pages: they do mention Arduinos, but only in passing.

I just want to screw about with this for fun, I'm not sure which version to get and whether to buy a big starter kit, or what.

A lot of us in that thread dislike Arduinos, but we'll still help you out, come post about what you're up to!

movax
Aug 30, 2008



Cockmaster posted:

It's not a matter of directly competing with professional-grade hardware, it's a matter of creating a simple, inexpensive solution for driving hobbyist-level CNC machines. For $25 you get a complete controller that could easily be built into a control box, and if you're running without an OS it'll be way less likely to crash in the middle of a program. It'd be especially nice for 3D printing and complex carving where you're often running for hours at a time.

Xenomai is another great RT framework for Linux. We regularly close 1MHz+ control loops using regular x86 hardware running Xenomai, talking to FPGAs over HT or PCIe. I don't think that kind of latency is needed for a CNC; having a RT framework and a system where you can completely kill off any type of power-management (no need to worry about states/ASPM/etc on the RPi) would be helpful.

I think on the RPi we'll just have to wait for someone (or DIY) apply Xenomai/similar patch to a stock kernel, strip it down and start benchmarking jitter/latency on various interfaces.

movax
Aug 30, 2008



JawnV6 posted:

Picking one of these up from a coworker who doesn't have time to play with it. Basically I want to hook it up to HDMI, ethernet, and a keyboard and get a full-screen telnet client on my TV. It should be able to handle that pretty easily, right?

Post it on Hack-A-Day once you do that.

e: you may need to blink a LED as well

movax
Aug 30, 2008



Snak posted:

I know nothing about SD cards, what is a good place to buy one? Is it worth paying shipping to buy one online somewhere or should I just get one at walmart?

I ordered on July 13 from Newark and mine shipped July 30th. I just need and SD card and a power supply.

You'll pay a lot at WalMart. The danger on-line is in fakes and lovely cards. Endemic on eBay, but you can even get bitten by that on Amazon (if you're not careful and don't double-check that you're ordering from Amazon and not fulfilled by x). That said, Amazon could be a good place as long as you make sure it is from Amazon, or you can watch SlickDeals to see when they go on sale.

movax
Aug 30, 2008



syphon posted:

Anyone try building a Pi Supercomputer using the following guide yet? At the very least, I'm interesting in picking up a second one to see how it does.

http://www.southampton.ac.uk/~sjc/raspberrypi/

The only thing stupider than this being academic "research" / grad school material is the amount of money they spent on it. Seriously inducing, five loving thousand dollars (chump change in academia, but still)

That said, by all means pick up a second one to play around with but don't expect anything balls-shatteringly awesome out of it. For cheap "supercomputing"/parallel stuff, the Kickstarter for the Parallela just ended I think. There's always the $0 method of leverage your existing GPU, but obviously there is quite a learning curve there.

movax
Aug 30, 2008



Puddin posted:

gently caress me. So I put the case on my Pi and it somehow breaks one side of the clip that holds the SD card in.

Which also means the car doesn't stay on the contacts, so now its useless.

loving hell.

So the SD card slot/holder is broken? Pretty easy to replace, pay your local nerd who knows how to solder some beer and it'll be good as new.

movax
Aug 30, 2008



People will Kickstart almost anything Pi related it seems.

It's a decent idea; I didn't realize you could get $34,000 for a breakout board that lacks any SMA connectors as well. (Though maybe the modules you solder to the board have the SMAs).

movax
Aug 30, 2008



So I've been doing some RFID installs lately, and it struck me that instead of paying HID a ton of money for controllers and such, on interior doors I could use a cheap, microcontroller based thing with Ethernet...or, a $25 Rasp Pi.

So I guess question is, what are the GPIO interrupts like / determinism on the Pi? It's a standard Wiegand interface, so I'll have two lines I need to sample. I figure I can write my own kernel-space driver or something to improve performance if needed.

I figure worst-case, I'll build a really tiny ATTiny or similar device to do the Wiegand interface, and act as a I2C slave (and run a pin to the GPIO to serve as an INT line). Pi inputs aren't 5V tolerant either

movax
Aug 30, 2008



HATE TROLL TIM posted:

Why not use a Teensy + WIZ812?

Teensy 2 uses an Atmel while the new 3 actually has an ARM onboard. Lots of IO to mess with on those and they're cheap ($16!)

I suppose you could do it on the RPi though. If you're running Linux you're not going to get true realtime control of the GPIO though, if that's what you're after. For what it's worth though you could install RiscOS and code it in ASM.

Yeah, I think I'm going to end up doing a PIC18 as an I2C slave. The PIC18's 5V tolerant, so I don't have to add any interface circuitry and it should get me up and running pretty quick I think. I'll just run one output to the RPi to serve as an alert that it should read data from the PIC via I2C, and IRQ off that.

I thought about doing it 100% embedded, but I don't have the time to really engineer the system / validate its functionality, and even though this door is not the most important in the world, I'd feel really lazy doing authentication without SSL/TLS, and apparently the Microchip TCP/IP stack's implementation is woefully out of date.

Though I did discover they make a big brother to the ENC28J60 w/ hardware crypto, which is cool.

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movax
Aug 30, 2008



I use HerpDerp for YouTube which replaces all YouTube comments. Vastly improved user experience.

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