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FeersumEndjinn
Posts: 148
Joined: Mon Nov 21, 2011 4:02 pm

Re: GPIO addressing

Wed Nov 23, 2011 11:53 am

As a old school \'hacker\', i.e. someone who likes pulling things apart and trying to make them better, I\'m looking forward to using my Raspberry Pi in electronics projects. I know bash and use linux a lot so this is the ideal opportunity for me to jump from 64Mhz processors to 700Mhz!

However I do have a few questions - my apologies if these have been answered previously but I couldn\'t find the details I needed on any of the wiki\'s.

1. I notice that the Raspberry Pi has 26 general GPIO available at (I believe) 3.3v, but is that same 3.3v broken out somewhere and made available to power my projects, avoiding batteries?

2. What is the maximum source current and maximum sink current of the GPIO lines?

3. I believe they are 1.27mm pitch - Are you aware if a ribbon connector socket exists in that dimension? If the GPIO was connected to using a ribbon cable it would prevent people burning out their Raspberry Pi by directly soldering to it (other than to install a socket).

4. How are the GPIO lines addressed? i.e, how does the base operating system see if a pin is HIGH/LOW?

Many thanks in advance.
Morrolan / FeersumEndjinn

"And the lord God said unto John, 'Come forth and receive eternal life', but John came fifth and won a toaster."

eggn1n3
Posts: 106
Joined: Fri Jul 29, 2011 10:36 am

Re: GPIO addressing

Wed Nov 23, 2011 12:05 pm

I believe the new Raspi version has 16 I/O pins with 2.54mm pins (you need to solder them yourself).
Concerning question 4, I would like to know that too...

fdufnews
Posts: 289
Joined: Fri Oct 07, 2011 5:37 pm

Re: GPIO addressing

Wed Nov 23, 2011 12:12 pm

1) don\'t know but there is a 5V line on the GPIO port
2) unknonw at that time but you\'d better suppose the IO have low fanout and put buffers on your extension. And it is a good protection for the processor.
3) no 2,54mm
4) look here : http://www.raspberrypi.org/forum?mingle ... pic&t=1115

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FeersumEndjinn
Posts: 148
Joined: Mon Nov 21, 2011 4:02 pm

Re: GPIO addressing

Wed Nov 23, 2011 12:25 pm

Sorry, had read another post that assumed 26 I/O.

If there is 16 GPIO then, is there enough space around the footprint to sit a ribbon cable socket?

i.e. could I sit this on the board directly wired to a ribbon cable: http://www.ebay.co.uk/itm/16-Pin-Socket ... 3f05fd3a5b?
Morrolan / FeersumEndjinn

"And the lord God said unto John, 'Come forth and receive eternal life', but John came fifth and won a toaster."


jamesh
Raspberry Pi Engineer & Forum Moderator
Raspberry Pi Engineer & Forum Moderator
Posts: 25466
Joined: Sat Jul 30, 2011 7:41 pm

Re: GPIO addressing

Wed Nov 23, 2011 4:51 pm

[quote]Quote from FeersumEndjinn on November 23, 2011, 12:25
Sorry, had read another post that assumed 26 I/O.

If there is 16 GPIO then, is there enough space around the footprint to sit a ribbon cable socket?

i.e. could I sit this on the board directly wired to a ribbon cable: http://www.ebay.co.uk/itm/16-Pin-Socket ... 3f05fd3a5b?

[/quote]

Probably, although better to have a plug/socket approach I think. Parts should be readily available to 1) Solder plug on to board 2) IDC socket on ribbon cable.

Should fit fine.
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