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Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 12:19 am
by liz
A bit of a treat for Monday morning (very early Monday morning - as far as I\'m concerned, it\'s still morally Sunday). The pinouts for the Raspberry Pi are now on the main page.

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 2:53 am
by radu
Any API to access the GPIO pins?
Can they be accessed by MMIO or something?

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 3:29 am
by tntexplosivesltd
We (the community) have to write our own drivers iirc. Same for SPI and I2C

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 4:32 am
by zerth
Are the DNC pins completely unavailable, or can we possibly access them elsewhere on the board with an exacto knife and some wire? :)

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 5:39 am
by abishur
Considering the over all size of the r-pi itself and the layered board aspect I\'m gonna guess no :P A cut with the exacto knife can take out a lot more than just the top layer (assuming, of course, that the correct lines are actually on the top PCB layer itself.)

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 7:15 am
by ansbaradigeidfran
[quote]Quote from liz on November 28, 2011, 00:19
A bit of a treat for Monday morning (very early Monday morning - as far as I\'m concerned, it\'s still morally Sunday).[/quote]

Posting GPIO pinouts on the Sabbath? :P

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 7:42 am
by zerth
[quote]Quote from abishur on November 28, 2011, 05:39
Considering the over all size of the r-pi itself and the layered board aspect I\'m gonna guess no :P A cut with the exacto knife can take out a lot more than just the top layer (assuming, of course, that the correct lines are actually on the top PCB layer itself.)[/quote]

I was thinking more of using it to scrape the mask off a pad or trace so I could solder a connection, not cut one. :)

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 8:20 am
by dpawson
\"We will not be making the boards with pins in place, in order to shave some cost off the build; you’ll have to solder them on yourself.\"

With what sized holes? Judging by the board design not very big? What pins will fit? Source?
With your intended audience has the layering been thermally guarded to account for hamfisted soldering in this area?

I wonder just how much has been saved by this bit of ... thinking, if that\'s not too kind a word.

IMHO a bad decision that will come back to bite you guys.
A wonderful beancounterlike decision?
Or the first reason to doubt the rpi?

Dave

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 8:34 am
by jacklang
As I said in the main post:
Its not primarily cost saving, but a request from the community.
Some wanted the pins on top of the board, others underneath. Some wanted straight pins, others right angled, and a few want to solder wire direct to the board. The holes are through hole plated for easier soldering.

The pins are at 2.54mm/0.1inch spacing

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 8:43 am
by Jongoleur
There are far too many B-Ark candidates here.... :-)

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 9:36 am
by NoSuchNick
Thank you for the pinout liz, there goes my productivity for the day ;)
Just to add to all the other questions:
Can we use the 5V pin to power the r-pi or are there diodes or something similiar that would prevent that?

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 9:38 am
by carlosfm
As I suspected, there\'s no digital audio. No I2S...

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 10:48 am
by FeersumEndjinn
The GPIO can be accessed in the standard linux way - by reading/writing text files in /sys/class/gpio.

http://www.mjmwired.net/kernel/Documentation/gpio.txt

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 11:00 am
by Sylvain
FeersumEnd-jinn >> Won\'t it need a driver anyway ?

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 11:24 am
by FeersumEndjinn
From what I have read, yes a driver is still required, even if it is purely to monitor the correct lines for I2C, SCA/SCL etc. but as there are so many drivers already out there, it should be more a case of porting a driver rather than creating one from scratch. The Fedora guys might even end up doing that, so until the R-Pi is released I think we\'re a little in the dark - the GPIO drivers aren\'t listed on the WIki page of stuff that needs working on by the community.

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 11:28 am
by gimliflea
Can anyone confirm if the JTAG connector will still have pins.
I really would not let myself near this board with a soldering iron.

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 1:43 pm
by abishur
[quote]Quote from carlosfm on November 28, 2011, 09:38
As I suspected, there\'s no digital audio. No I2S...[/quote]

I don\'t remember i2s ever being mentioned as a contender on the board. Besides it still has HDMI if you want digital audio, and a high quality 3.5mm analog audio jack. You\'ll be just fine. As my wife would say, \"Ah the troubles one must bare in a first world country!\" :P

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 1:49 pm
by liz
[quote]Quote from gimliflea on November 28, 2011, 11:28
Can anyone confirm if the JTAG connector will still have pins.
I really would not let myself near this board with a soldering iron.[/quote]

\'Fraid not - and I suspect it\'s not the JTAG you think it is, either (i.e. it\'s not ARM JTAG). ARM JTAG will be available will be available via a reconfiguration of the GPIO pins.

I am legendarily cack-handed, and even I can solder this stuff, by the way. No reason at all you shouldn\'t be able to (and it\'s fantastic for the self-esteem)!

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 2:07 pm
by hippy
[quote]Quote from dpawson on November 28, 2011, 08:20
\"We will not be making the boards with pins in place, in order to shave some cost off the build; you’ll have to solder them on yourself.\" ...

IMHO a bad decision that will come back to bite you guys.
[/quote]

I think it\'s a good decision; as well as saving costs it allows much more flexibility for those wanting GPIO access. It will inconvenience some but overall I\'d say it\'s more gain than loss.

Those who are looking at hardware interfacing will likely have the knowledge, skills and tools to undertake soldering and it is far easier to add headers than remove them. With 0.1\" pitch headers there shouldn\'t be any greater difficulties with an R-Pi board than any other.

Most hardware interfacing will involve some circuit construction and soldering anyway but it is possible to have non-soldered interfacing and the decision may present difficulties for some. I expect the issue will be resolved at some time in the future - most likely when the foundation release official add-on boards for the R-Pi - otherwise people will have to learn soldering or find someone to do that for them. If there is the demand I would expect others to offer such a service and that could perhaps be done by resellers or those providing add-on hardware.

GPIO hardware interfacing isn\'t an essential for \'learning to program\' and there are other means to provide hardware interfacing via USB, though that will often simply move the difficulty of soldering the R-Pi to soldering to those interfaces.

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 2:12 pm
by liz
Couldn\'t have put it better myself, Hippy - that was exactly our reasoning.

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 2:14 pm
by ukscone
I actually thought the real reason was that it would draw blood if you stepped on a raspi and that \'elf and safety would get a tad annoyed

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 3:47 pm
by Gert van Loo
On I2S: Yes it has I2S (and PCM)
The number of different things the GPIOs can do is larger then specified in Liz\' list.
If Liz would have written the complete list down 95% of the readers would not have understood it and the number of emails would have gone up exponentially. Also we will not have Linux drivers yet for a lot of these special I/O modes . So for now we KISS (Keep It Simple, Stupid). To use two well known phrases:
+ Watch this space.
+ But don\'t hold your breath.

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 5:20 pm
by Burngate
I put this on the front-page replies-list but here might also be useful
[img]https://sites.google.com/site/burngateh ... /GPIOs.gif[/img]

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 5:29 pm
by abishur
nice burngate!

Re: GPIO pinouts confirmed

Posted: Mon Nov 28, 2011 5:57 pm
by carlosfm
[quote]Quote from abishur on November 28, 2011, 13:43
[quote]Quote from carlosfm on November 28, 2011, 09:38
As I suspected, there\'s no digital audio. No I2S...[/quote]

I don\'t remember i2s ever being mentioned as a contender on the board. Besides it still has HDMI if you want digital audio, and a high quality 3.5mm analog audio jack. You\'ll be just fine. As my wife would say, \"Ah the troubles one must bare in a first world country!\" :P[/quote]

If you want to interface directly to an audio dac chip, you need PCM and HDMI is useless. Don\'t even mention it.
Audio in HDMI is mixed with video. You need an AV amp to extract the digital audio and deal with HDCP, if present.

I\'ll check the audio quality on the analog audio jack too, but I doubt on the \"high quality\" on a portable device, don\'t get me wrong.
I\'m an audiophile, who usually builds and/or mods his own audio gear.

[quote]Quote from Gert van Loo on November 28, 2011, 15:47
On I2S: Yes it has I2S (and PCM)
The number of different things the GPIOs can do is larger then specified in Liz\' list.
If Liz would have written the complete list down 95% of the readers would not have understood it and the number of emails would have gone up exponentially. Also we will not have Linux drivers yet for a lot of these special I/O modes . So for now we KISS (Keep It Simple, Stupid). To use two well known phrases:
+ Watch this space.
+ But don\'t hold your breath.
[/quote]

Ah, there is hope, then.
Thanks for confirming, Gert.