sylvan
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Re: BCM2835 datasheet

Wed Dec 21, 2011 4:18 am

Quote from obarthelemy on December 21, 2011, 00:01
I fear hardware modding of that level on the Pi will be impossible due to the technologies and processes used. No hope of expanding RAM, using unwired pins... I fear anything that's not brought out to a connector will be too small and sensitive to be tinkered with.

Of course.

And of course it would be good to know the true capabilities of those pins that are brought out. The linux driver model is very limiting. And if that is the limit, oh well. But if the hardware is capable of more, those artificial limits are an immoral waste that I consider immeasurably worse than buying something made in china. (tying two threads together)

richcole
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Re: BCM2835 datasheet

Wed Dec 21, 2011 4:54 am

I grew up with the Amiga 500. It was great because the ROM Kernel manuals explained the design of the operating system and the workings of the hardware. I think you're being cruel to the next generation if you withhold details of the hardware.

There's other hardware out there though that is documented, there's QEMU and there's the internet. So the next generation is not so limited by the Raspberry PI hardware not being open. They'll just have to look elsewhere.

regards,

Richard.

dattaway
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Re: BCM2835 datasheet

Wed Dec 21, 2011 6:02 am

Well, this makes things more interesting. I used to love poking random bits into I/O space on early 8 bit computers and seeing what would happen. Sometimes it takes good old fashioned hacking to build great documentation...and awesome tools and apps are often a side effect.

bradburts
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Re: BCM2835 datasheet

Wed Dec 21, 2011 8:11 am

Agreed.
But they are not cruel, it is an unfortunate limitation of the commerical world, so make sure we all say thanks for the manuals that we get, a lot is being given.

PS
You can do register programming with a PIC or Arduino etc.
The point is that the PI will (big hope) fill UK schools. Once that is done the tick box managers will say 'why do you need another computer, you have a room full of them'.
So it would be great if the PI can do it all.

jamesh
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Re: BCM2835 datasheet

Wed Dec 21, 2011 9:38 am

How about looking at this from the other direction.....rather than what you WON'T get.

What you DO get :

A 700Mhz Arm
Highest powered GPU per watt available
> Wii levels of 3D
HW accelerated 2D
1080p30 encode/decode to h264 (licence included)
Camera interface
17 GPIO's, plus some interesting interfaces.
1080p HDMI
Composite out
Credit card form factor
Custom Linux and standard drivers for all the above
Documentation for the GPIO's
USB and ethernet
Audio out.
Teaching materials tailored for the device
People building (in their own time) custom HW interface boards
Lots of very smart Broadcom (and others) people doing all the heavy lifting getting the above working.

What you don't get:
Full documentation of the hardware/GPU.
Access to the GPU's MIPS except through drivers.

As tradeoffs go, I think that's worth $35. I'd stop complaining IIWY.
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Motley
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Re: BCM2835 datasheet

Wed Dec 21, 2011 9:40 am

Unfortunately the sad fact is that the "commercial world" these days is patrolled by a myriad of litigious companies and patent trolls so everyone ends up keeping everything secret.

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Re: BCM2835 datasheet

Wed Dec 21, 2011 9:43 am

Quote from walney on December 20, 2011, 15:16
Quote from bradburts on December 20, 2011, 14:48
Is the GPS so that if I steal your Pi you can locate it? ;)

Quote from jamesh on December 20, 2011, 14:39
...have so far failed to get a USB GPS adapter going...

Obviously not ;) . i would be interested in hearing which adapter - I was looking at a Bluenext BM903S (partly as a means of getting around the lack of battery backed clock, partly because it's cheap - and so am I).

Yes, it is a Bluenext, but I think the reason it didn't work was that I didn't have USB serial enabled in my kernel build, and I haven't had time to check any further. Might have a go over Xmas, but I cannot build the kernel at home which would be a problem!
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Re: BCM2835 datasheet

Wed Dec 21, 2011 9:51 am

Exactly. Did you see that Apple have knobbled HTC over technology that seems very much to be 'cut and paste'.

Jamesh, no-one is complaining.
PI and Gert board with some explation of GPIO will be pretty good, thank you very much ;)

My informal guestimate is that that 15% or so think that register programming has some use in education.
About 25% think that PI use should be mainly with HLL.
The rest have been confussed into thinking that a discussion on the role of computing education is a complaint or critisism of Broadcom, it is not.

Now I know that you do not think that register programming is needed these days. And you're helping write a manual which will support us doing it! Brilliant, truely, thanks. :)
I could not find a signature box but have updated my profile ;)

wantmypi
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Re: BCM2835 datasheet

Wed Dec 21, 2011 10:08 am

Quote from liz on December 19, 2011, 11:05
First off, I continue to feel deep snark at all the Broadcom hatred. It really wouldn't have mattered which SoC we chose from the open point of view: NOBODY makes a chip of this sort

Well I will give you *MY* perspective on this, and this is my view, its blunt, and none of that mamby pamby kumbaya PC fluff.

Your calling this a "developers" board... well to many of us that means something that obviously is different than yours, which I find hard to understand when many of the persons involved in the project are involved in the semiconductor business, and thus had to use "development boards/kits" as part of their education.

When I was in my EE course, we had to use a Motorola 68HC11 development board/kit.This was a board with processor, various interfaces for debug, interfacing, A/D, D/A, breadboard area. AND 2 FULL BOOKS of specifications on how to use it. From the processor commands, to the interfaces, to the A/D, D/A etc...

Thats what I [we] want. ..... but... what we get is NO! NDA! TOP SECRET! That doesn't work, period.

I am NOT discussing the GPU! I am talking about a data and specification sheets/books with pin outs, 1=Vcc, 2=GND, 3-16 = A0-A15, etc..

How to use the DSP(s), A/D, D/A etc. if applicable, thermal specifications etc...

NO! CAN'T HAVE THEM!

NO NO NO NO! This is all material that any educational program will need to create curriculum! Additionally this is material that those in the Ardurino/Beagle/Panda community need to do things. I learned alot from those books, more than just what was taught in the curriculm!

How do I know whats possible with this chip and thus the Raspberry Pi if I don't know its capabilities? ? Does it have a D/A, or A/D I could use to interface to things? How do I control it, access it? ? ?

This data should be on Broadcomm's, or any other chip makers site, in the publicly accessible area, period. Full stop. NO ifs, ands, buts, registration. For decades all this stuff was available via databooks that were purchased from the manufacturers, the modern age, ie: internet comes along, and its all GONE! Behind NDA BS. This is the same sort of nonsense the TIA/EIA does with standards charging hundreds of $$$ for PDF's.

You tout that x,y,z, have access to the information behind the NDA wall, so!?? ! What good does that do ME?!? I don't have access to it to determine what I might be able to do with the Raspberry Pi!

Now as for the GPU.... well... I am NOT in favor of closed binary blob. READ AGAIN.. NOT IN FAVOR. I would much rather see a fully open sourced and public code for it.... BUT so long as a 100% PUBLIC API which allows access to 100% of the features of the GPU, I can live with it... Is it my first choice, no, but I can handle it. I don't have the issues with say the nVidia OEM drivers in Linux that some factions do. I want to get the most out of my nVidia cards, and if that means the OEM Drivers, fine with me.

Yes, some have their panties in a twist over these closed blobs in Linux (see Debian and their idiotic lack of firmware etc.)... again, I would much rather see the Linux development community able to participate with the OEM versus having to reverse engineer it, which is why I don't use nouveau (crud!). I think Broadcomm could look to nVidia who is starting to see the light, starting, in re CUDA code. Yeah its still restricted to some group that meets certain criteria and still probably under NDA, but they are starting to crack!

Now, mention Broadcom to many in the Linux community, and the reaction you get will be exactly what you've experienced. Broadcom has been used as the poster child for exactly what NOT to do to enamor yourself to the community. Next there is this whole lawsuit thing with several companies from Qualcomm to SiRF to ..... But....but... yeah I know the refrain. I am not interested, I don't believe in IP, copyright, trademark, patents, trade dress. So your barking up the wrong tree with me on that.

I will say that Broadcom has made progress to be a better member of the Linux community in regards to releasing OEM drivers. They have the past of their own creation to live with, and thats a big hurdle to overcome. I will tell you that I am not completely enamored with hearing Broadcom, BUT I am willing to give them a chance to PROVE they WANT TO BE A PART OF THE COMMUNITY. No, its not going to take much to change my opinion. Something thats not helping, LACK OF FULL DATA SHEETS, PIN OUTS, DSP functions, etc... I fully believe that a little pressure from an OEM customer of Broadcom and this cheap deal on chips is over. You don't think it will happen? HA.. in this litigious world, your kidding yourself. If they feel threatened in some way they will cut this off. One little bit of whining from an OEM customer who is purchasing $$$$$$$$$$$$$$ worth of chips, versus some little charity.. Who you think will win? DING! Big corporations and $$$$.

I am very intrigued with the Raspberry Pi, for MY OWN USE and MY PROJECTS uses. I personally do not care one bit about the foundations goals, plans, or reasons for its development. If I get to benefit from this, and they use my $ to further their goals, and I get my benefits, fine so be it. The use of the Broadcom SoC, is some what of a turn off for being Broadcom, along with a couple of other issues, but may be worked around if done right by the Raspberry Pi group.

So what I [many] want is what I need to be able to do things with this device, pin outs, functions, etc.. I [we] are not asking for the masks to make the SoC, but I need to know what the capabilities are to determine what I might do with it.

So lets solve the acrimony, and lets get the data I [many] want released, and then we can all let our imaginations go wild on what we might be able to create with the Raspberry Pi devices.

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JeToMad
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Re: BCM2835 datasheet

Wed Dec 21, 2011 10:09 am

Quote from bradburts on December 21, 2011, 09:51
Now I know that you do not think that register programming is needed these days. And you're helping write a manual which will support us doing it! Brilliant, truely, thanks. :)
I could not find a signature box but have updated my profile ;)


(OFF-Topic: In "edit your forum options" you can add a signature ;) )
Greetings from Spain!

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walney
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Re: BCM2835 datasheet

Wed Dec 21, 2011 11:14 am

@wantmypi
To speak bluntly, I always find that RANTING and STAMPING MY FOOT gets me exactly what I want. Especially if I am DEMANDING STUFF from people who aren't getting PAID for what they are doing, but are doing something that they believe in (even if you don't). So let's solve this acrimony by showing a little CIVILITY.

You haven't been mislead as to what you will be getting. If a $25 board without detailed documentation doesn't suit YOUR needs for what YOU want to do, or if YOU are worried about commercial pressure affecting it's long-term availability... just look elsewhere. (Maybe you just can't have your pi and eat it?)

jamesh
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Re: BCM2835 datasheet

Wed Dec 21, 2011 11:16 am

@wantmypi.

No, its not a development board, so you are completely wrong there. It's a board intended for teaching. Look it up. Teaching, TEACHING. Not a development board.

The capabilities of the board for the end user are well documented (or will be on release). Note I say capabilities of the BOARD, not the SoC. Those capabilities advertised will be accessible from Linux libraries. There may or may not be other capabilities that the SoC is capable of. You are *not* getting a board with those capabilities.

We are quite happy for you to be intrigued with the Pi and its capabilities, just don't expect to be able to use it beyond the advertised capabilities.

You don't believe in IP or the current patent issues. Fine. Neither do I. Unfortunately the rest of us have to live in the real world, where these are a fact of life. If you can't live with that, I'm sorry.

OEMS: Hmm, not really sure what you are on about here. Broadcom OEM are people like mobile phones companies, or set top box people. Neither of whom are threatened by the Raspi. I suppose it's a slightest of slight possibilities someone might get pissy, but very unlikely.

You don't care about the foundations goals. OK, your choice. It also the foundations choice to NOT CARE ABOUT YOUR GOALS EITHER if they don't match up with the foundations goals. Which since you don't care about the foundations goals they don't.

Since you want directness... You are talking rubbish. You have no concept of the realities of the commercial world out there that the foundation has to work with, and, to be really really blunt, DONT BUY THIS BOARD. You will only be disappointed that you cannot do stuff YOU think you need to do.
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tumblebomb
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Re: BCM2835 datasheet

Wed Dec 21, 2011 11:43 am

Even better answer than the one I was just hammering out. too right @jamesh

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Re: BCM2835 datasheet

Wed Dec 21, 2011 12:03 pm

Back on topic - or slightly more so - maybe my confusion is the same as many others'.

Eben has told us the GPU is analogous to the bios on a PC, but to me it seems more like the hardware on a pc's video card. How many people out there hack that? I haven't and I don't know if it's possible. Ball-park figures or even just anecdotal evidence would be helpful.

Also, since I know too little on the subject, where exactly is the boundary between open-source and Broadcom's IP? Linux appears to have built-in, stuff that makes the hardware look like files. That appears to talk to the hardware via message-passing. Are we allowed to know how to send a message? Somewhat like I know how to post a Christmas card, and recieve one, but what happens after I put it in the post-box or before it comes through my letter-box is beyond my ken.
If so, I'm happy.

Or is the message-generation also Hidden? If so I'm less happy, though I'll live with it.

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JeToMad
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Re: BCM2835 datasheet

Wed Dec 21, 2011 12:20 pm

Quote from Burngate on December 21, 2011, 12:03
Are we allowed to know how to send a message? Somewhat like I know how to post a Christmas card, and recieve one, but what happens after I put it in the post-box or before it comes through my letter-box is beyond my ken.


As I understand it, with Broadcom (and many others, such as TI with the OMAP chips) is exactly like you say: You know how to write and read the Christmas cards, but know nothing about how the delivery goes.

With open source, you can look at how the delivery is done, and change it if you feel you know a better way. And not only change it for you, you can try to have your change accepted and used by all the people that sends and reads cards ;)
Greetings from Spain!

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Re: BCM2835 datasheet

Wed Dec 21, 2011 12:28 pm

In general, almost everything on the Arm is OSS. There are a couple of closed source libraries - OpenVG and OpenGLES. These libraries need to communicate with the GPU to get stuff done, and they do this via a message passing interface. The low level driver for the message passing is in kernel space and therefore must be OSS. Any GPIO libs supplied is somewhat different, that all stays on the Arm side and just pings registers - I don't know if they are going to be OSS. I hope so.

The actual format of the messages is not documented (and completely GPU specific), but that really doesn't matter as the libraries do all that stuff for you- you just call the *standard* OVG, OGLES api's and it magically (With the help of Elves) works.

All the code running on the GPU itself is private, but without the custom compilers etc, you can't do anything with it anyway, and it's complexity means most people coming to it would throw up their hands in complete bewilderment.
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Re: BCM2835 datasheet

Wed Dec 21, 2011 12:52 pm

(OFF-Topic: In "edit your forum options" you can add a signature ;) )

Thanks, I was looking at the Wordpress page, doh ;)

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Re: BCM2835 datasheet

Wed Dec 21, 2011 1:13 pm

Is it safe to come back in the room again?

I said that no-one was complaining and looks like I have been turned into a liar, doh!

People have a right to earn their bread.
The line between commerical incentive & commerical oppression, patent trolls etc is not going to get resolved in this forum.
Broadcom are not Apple (think that its legally safe for me to say that!) and by all accounts have been supporting this project beyond reasonable expectations.
I would like to keep away from commerical/fully open because it mostly makes it impossible to discuss low level programming.
It is what it is. Simply present examples of what we want to teach and things may happen. The datasheet was not on the menu until recently. :)
Open would be best for education as it would be best for me to code all day (rather than perform management duties). Not going to happen, not unless we pay more or I take a pay cut.

I think the reality is/will be that quite a lot will be open and even better well documented.

Also, since I know too little on the subject, where exactly is the boundary between open-source and Broadcom's IP? Linux appears to have built-in, stuff that makes the hardware look like files. That appears to talk to the hardware via message-passing. Are we allowed to know how to send a message? Somewhat like I know how to post a Christmas card, and recieve one, but what happens after I put it in the post-box or before it comes through my letter-box is beyond my ken.
If so, I'm happy.
The driver model is well documented. Its quite easy to create a Linux drive because all drivers present this file interface. The files which you present can change with the driver, e.g. you may have a 'status' type file. The low level gubbins (that talks to memory/registers) is just like any other low level device driver, varies from device to device, but hooks into the /dev files.

I happen to think that the PI is a development board and can be used to teach that way. As things stand and more so as more and more people get on board.

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scep
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Re: BCM2835 datasheet

Wed Dec 21, 2011 2:16 pm

@wantmypiandeatit

[embed][/embed]

bradburts
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Re: BCM2835 datasheet

Wed Dec 21, 2011 2:33 pm

scep,
wantmypiandeatit is not real.
He is a 'tool' to bring this thread to consensus, you watch, you won't see him again unless we start to argue.

Now I have set that one up, so someone finish it ;)

jamesh
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Re: BCM2835 datasheet

Wed Dec 21, 2011 2:45 pm

I think you are right - he is a tool.
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scep
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Re: BCM2835 datasheet

Wed Dec 21, 2011 2:48 pm

Quote from bradburts on December 21, 2011, 14:33
wantmypiandeatit is not real.
Are you suggesting that people actually register under an assumed name and post a troll-rant just to get a reaction?! Nah - that wouId be too sad and desperate :D

bradburts
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Re: BCM2835 datasheet

Wed Dec 21, 2011 2:50 pm

@Jamesh
Ta ching!
Didn't see you as the funny man to my straight man ;)

bradburts
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Re: BCM2835 datasheet

Wed Dec 21, 2011 2:51 pm

I have floated my theory, given my prediction.
Wait and see if I am right ;)

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Re: BCM2835 datasheet

Wed Dec 21, 2011 3:08 pm

Quote from scep on December 21, 2011, 14:16
@wantmypiandeatit

Books for Christmas!?!?!?!?!


The irony is that the curious do want books for Christmas :-)

All I want for Christmas is my datasheet,
my datasheet,
my datasheet...

Hey, if we can't get an actual RasPi, at least with a data sheet we have something to drool over and imagine the fun when RasPi hardware does show up. :-)

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