tufty
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Re: What software development environment...

Mon Nov 28, 2011 11:04 am

They should decide?

Remember - Even the first 10K (and onwards) are beta boards, and the mechanical layout of the final release will probably be subtly different to allow for mounting holes and so on. Boards produced to match the layout of the beta boards may or may not match the "final" design (and yes, this is, to some extent, a statement that basing a business such as "producing addon boards for Raspberry Pi" on a beta product is a bit daft).

Also, given that the pinouts are a 2 row setup on one corner of the board, using a "hard" setup like Arduino's "shields" isn't gonna work, as there's no significant mechanical support. "Ram Pack Wobble" or simply tearing the traces off your Pi / addon board / both are a distinct possibility.You're better off using a cable.

Simon

dpawson
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Re: What software development environment...

Mon Nov 28, 2011 11:16 am

Quote from tufty on November 28, 2011, 11:04
They should decide?

Remember - Even the first 10K (and onwards) are beta boards, and the mechanical layout of the final release will probably be subtly different to allow for mounting holes and so on. Boards produced to match the layout of the beta boards may or may not match the "final" design (and yes, this is, to some extent, a statement that basing a business such as "producing addon boards for Raspberry Pi" on a beta product is a bit daft).
Simon

Sage advice to never buy alpha/beta hardware and rev 1.0 software?

IF I buy a beta, I guess it will only be trustworthy for sw dev, since the
OS of Linux, HW of arm... (can they change the cpu? Are ARM pinouts common across recent hw?) should be stable (for some todays definition of stable).

IMHO yes, the rpi team should decide layout/mounting/interface hw. We wouldn't expect Motorola/Nokia to ask us what sockets we want?
We judge them by how well they decide.

Dave

tufty
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Re: What software development environment...

Mon Nov 28, 2011 12:37 pm

IMO, a lot of it comes down to us being very privileged to be allowed to get in "at the ground floor", as it were. Alpha and beta level access are usually reserved for "development team / very close commercial partners", and alpha / beta boards almost never correspond even remotely to the "final product" except in technological terms. I've seen "beta" products that were spread across 3 circuit boards connected with ribbon cables, with hand-soldered jumper cables all over the place where traces have been missed, and which only worked "reliably" at fractions of the intended final clock speeds. Fine for developing on, but not good publicity if the public got to know. Interfacing layout usually consists of a bunch of pads splattered over both sides of the boards (and a standard JTAG header if you're lucky).

Making the betas available to the public (and particularly a public who are not related to whom the final product is intended) is almost unheard-of in the commercial world, and is, I would imagine, putting quite a lot on pressure on the "team", who are now committed to delivering a non-kludgy and "almost final" product to a public who, frankly, whine an awful lot (not a comment aimed at anyone in particular, of course).

So no, it's not a "don't buy alpha/beta" statement; more a warning that we shouldn't expect too much, and a plea to cut the team some goddamn slack. They're doing something astounding, both in terms of what they are developing, which could turn out to be one of the most important devices to be released in recent years, and in how much information they are giving out in the process of developing it.

Final mechanical format, including interfacing layout, will come with the final boards. That may or may not correspond to what we see at the moment (and may, or may not, be influencable by those wanting to produce addons). For now, live with having to solder headers or cables into place. It's no big frickin' deal.

Simon

dpawson
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Re: What software development environment...

Mon Nov 28, 2011 1:34 pm

Quote from tufty on November 28, 2011, 12:37
IMO, a lot of it comes down to us being very privileged to be allowed to get in "at the ground floor", as it were. Alpha and beta level access are usually reserved for "development team / very close commercial partners",

Were that the case here I wouldn't say a word Simon.
It's not. We haven't been told anything about early release/final release so we all make our all assumptions (rightly or wrongly).



Making the betas available to the public (and particularly a public who are not related to whom the final product is intended) is almost unheard-of in the commercial world,

This isn't being pushed as a commercial operation though? It's a registered charity, clearly strapped for funds yet doing nothing to raise them?

So no, it's not a "don't buy alpha/beta" statement; more a warning that we shouldn't expect too much, and a plea to cut the team some goddamn slack. They're doing something astounding, both in terms of what they are developing

No quibble there, I'm full of admiration

Final mechanical format, including interfacing layout, will come with the final boards. That may or may not correspond to what we see at the moment (and may, or may not, be influencable by those wanting to produce addons). For now, live with having to solder headers or cables into place. It's no big frickin' deal.

for the quoted market? It could be IMHO. If it were being sold as suitable for solder-heads, build-your-own-computer types, then I'd agree. It isn't.

I simply don't want the team to get a nasty backlash from a decision I see as being way-out wrong and unjustifiable IMO.

Dave

obarthelemy
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Re: What software development environment...

Mon Nov 28, 2011 1:44 pm

1- The Pi is mainly targeted at software, not hardware, hackers. Arduinos and such fill the hardware niche quite well already.
2- Hardware hackers, even of the wanabee level, are supposed to be able to solder leads to a board.

I'm not quite sure what the whining and lesson-giving is about.

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johnbeetem
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Re: What software development environment...

Mon Nov 28, 2011 3:21 pm

Quote from dpawson on November 28, 2011, 07:48
@johnbeetem Thanks for the explanation. I think the 'dedicated' 232 port would make a safer bet reading your post. I'm guessing the BCM2835 is an IO chip on the rpi? Without power management the risk of powering off in the wrong order sounds iffy.

"Note that there's also a version of the cable that speaks SPI, I2C, and JTAG. I think this is exactly the same as the UART cable except that it identifies itself as a different USB device so the appropriate device driver gets used. I would hope there's a way to specify USB device driver explicitly, as it would be nice to buy one of these cables and then use it as either UART or JTAG."
Yes that does sound interesting, though as above with the power shutdown caveats?


The BCM2835 is the RasPi SoC (System on a Chip). All the power management and I/O is in that chip, along with ARM processor, GPU, and PoP (Package on Package) memory. Some call this a MoC (Motherboard on a Chip).

As tufty points out above: "there is absolutely no protection on any of the pins". That's a bit strong, since chip I/Os almost always have some sort of protection usually in the form of internal diodes that prevent signals from falling below GND or exceeding VCC. However, the protection is very limited -- with a high enough voltage, everything is a fuse. A careful engineer likes to look at the data sheet to see what the absolute maximum ratings are on the pins to make sure power sequencing doesn't damage anything.

Regarding the FTDI cables, I recommend looking at their spec sheets, which include detailed schematics. You can also get FT232H data sheets. FTDI is interested in selling chips, and figure that publishing complete data sheets that answer everybody's questions saves a lot of customer support time and helps sell more chips. I find it astounding when chip manufacturers keep the user interface of their chips secret. For example, what if Intel had decided that they would only open the 4004 spec to certified cash register OEMs instead of publishing a full spec and selling to anybody? (The 4004 was Intel's first microprocessor, a 4-bit machine custom designed for a cash register company.)

dpawson
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Re: What software development environment...

Mon Nov 28, 2011 3:39 pm

Again, thanks @johnbeetem. Yes, MoC does seem like a fair
description. Limited protection also seems pretty accurate. I was
thinking along the lines of using the I/O for crude system
information via a couple of leds. I'll think more carefully till
I can get a safer IO interface.

I agree about the FTDI interface and their data sheets. Eminently
sensible decision IMHO. My first cpu was a 4004, I read the spec
sheet returning from Welwyn to home on the train and found it
quite fascinating. That and its big brother were used in a
terminal I had to maintain. Hate to do the same to an ARM chip!
Heck of a train journey.

"You can also get FT232H data sheets."
http://is.gd/UYUTP5 as you say, complete with drivers.
How to win friends and influence customers?

Dave

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abishur
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Re: What software development environment...

Mon Nov 28, 2011 3:48 pm

Humming to myself "I'm going off the rails on a crazy train!" well it's your thread you can take it where you want it :P

Anyways, we actually been told an *insane* amount concerning the final boards! I mean most companies (be they for or non-profit) don't tell you squat. You're lucky to get a "heads up a new product is coming." Usually, it's just bam! here's the product, have a nice day!

But Simon's statement of making beta's available to the public might be better stated as "in any environment outside software" rather than specifically mentioning the commercial world. ;)

The sad truth is that the r-pi team receives a ridiculous amount of backlash for *every* decision they make. There's just no way to please everyone so they make the decisions that they think is best and you get a group that agrees with them and a group that disagrees.

Now on this particular issue... well I'm a fence sitter on this one. On the one hand I'm lazy and these are some small and closely spaced solder points. On the other hand, it protects the r-pi team from some knuckle head trying to plug who knows what to it, or jumping out the pins and then blaming the r-pi foundation for it (if a lady can sue McDonald's for have hot, hot coffee, then no one is safe!) and as obart mentioned, soldering is a level 1 skill for hardware people. If they can't solder on their own headers then they *REALLY* shouldn't be messing with gpio anyways as they'll still need to do a lot of soldering for anything else to do with the gpio. Plus on a device where they're having to watch every penny... er... pence being spent, then it makes sense to axe the gpio header pins as opposed to a truly useful feature... like ram, or an audio connector. :)
Dear forum: Play nice ;-)

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johnbeetem
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Re: What software development environment...

Mon Nov 28, 2011 3:49 pm

Quote from dpawson on November 28, 2011, 15:39
Again, thanks @johnbeetem. Yes, MoC does seem like a fair
description. Limited protection also seems pretty accurate. I was
thinking along the lines of using the I/O for crude system
information via a couple of leds. I'll think more carefully till
I can get a safer IO interface.


LEDs are pretty safe if you're using the RasPi GPIO header's 3.3V to power them. There are actually a couple of LEDs already on the PC board, but we haven't been told whether they're being populated, and people are arguing about what colour they should be as in The Restaurant at the End of the Universe.

dpawson
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Re: What software development environment...

Mon Nov 28, 2011 3:56 pm


The sad truth is that the r-pi team receives a ridiculous amount of backlash for *every* decision they make. There's just no way to please everyone so they make the decisions that they think is best and you get a group that agrees with them and a group that disagrees.

Now on this particular issue... well I'm a fence sitter on this one. On the one hand I'm lazy and these are some small and closely spaced solder points. On the other hand, it protects the r-pi team from some knuckle head trying to plug who knows what to it, or jumping out the pins and then blaming the r-pi foundation for it (if a lady can sue McDonald's for have hot, hot coffee, then no one is safe!) and as obart mentioned, soldering is a level 1 skill for hardware people.

I note the contradiction there? "some knuckle head trying to plug who knows what to it" yet, "soldering is a level 1 skill for hardware people."

Take one more. Warranty claims? A board comes back with huge brown
stains round the solder pads. Hey, this is no good. Valid claim?
Series of bent pins pulling the layers apart? Rather easier claim to reject?

As you say, some agree, some beg to differ.

I've said my piece. Dave

kme
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Re: What software development environment...

Mon Nov 28, 2011 4:07 pm

Quote from abishur on November 28, 2011, 15:48
Anyways, we actually been told an *insane* amount concerning the final boards! I mean most companies (be they for or non-profit) don't tell you squat. You're lucky to get a "heads up a new product is coming." Usually, it's just bam! here's the product, have a nice day!I so agree. The openness is fantastic.

Now I've already generated some noise with a "me too" post I might as well go slightly OT and suggest that whenever the forum software is going to be upgraded, please include a "thumbs up" system, so a post like this one can be avoided. However, refrain from a "thumbs down" option, as this seems to create a lot of negative mood. It's like the old saying "If you can't say anything constructive, then shut up". (Now I hope this was constructive!)

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Burngate
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Re: What software development environment...

Mon Nov 28, 2011 5:15 pm

A long time ago in a different universe ... If you bought a Sinclair audio power amp and it didn't work, you sent it back, they gave you new one, even if it was you wot broke it. (they were over-specing the chip, and letting you do the QC)
Not saying that's what the foundation would do - they're not Sinclair - but it seems for a lot of companies it's cheaper to replace than check and repair! It relies on the customers being reasonable, which by-and-large they are.
No idea what they're expecting in the way of returns, especially as they appear to be doing massive quality control, and no idea what proportion they're expecting in the way of user-generated faults, but I'm positive that if I've thought of something, they already have, and already done something about it!

shaurz
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Re: What software development environment...

Mon Nov 28, 2011 5:43 pm

I'm waiting for the hardware (should be not long now) and I will be programming directly on the device, not cross-compiling.

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