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AndrewS
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Re: We've just released the schematics!

Tue Apr 24, 2012 11:50 am

jbeale said:


I don't know how you found the patience to generate that!


  It was a very wet weekend…

I'm glad to see people appreciate it. If anyone spots any errors, I"m happy to fix them.

mjtessmer said:


Gert:  Can you tell us which pins the I2S signals are on?


That's covered in http://elinux.org/RPi_Low-leve.....eripherals and the BCM2835-ARM-Peripherals.pdf datasheet that it links to. I2S needs additional access to GPIO19 and GPIO20, which according to my tables are on BCM2835 pins G8 and E5, which are both currently not-connected.

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AndrewS
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Re: We've just released the schematics!

Tue Apr 24, 2012 6:51 pm

I've done a bit more analysis, and I've now managed to map the BCM2835 pins back to the RaspberryPi circuit board itself

See the images at the bottom of http://elinux.org/RPi_BCM2835_Pinout

(and I've added a link to the GIMP project I used to create those images to http://elinux.org/RPi_Hardware......2F_Layout )

Michael
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Re: We've just released the schematics!

Tue Apr 24, 2012 7:51 pm

Excellent work!  It would be interesting to number those vias in the second photo and report to which pins each is connected.  Are there any vias on the second photo that are connected to a chip pin that we otherwise don't have access?

Edit: no, doesn't look like it.  Unsurprising really, given the difficulty of getting the signals away from that area in general.

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AndrewS
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Re: We've just released the schematics!

Tue Apr 24, 2012 9:56 pm

Michael said:


It would be interesting to number those vias in the second photo and report to which pins each is connected.


I considered that, but the photo isn't quite sharp enough to follow all the traces (they're very close together!) and there's quite a lot of blind vias. But I don't mind if someone else wants to have a go

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jbeale
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Re: We've just released the schematics!

Tue Apr 24, 2012 10:24 pm

By the way, the best way to get a clear image of a PCB is to scan it on a desktop scanner, rather than photograph it. This should work at least for the bottom of the RasPi. From the top side, the tall components like the USB sockets may put the board itself out of focus.

(and if you really want to get crazy you remove most of the parts, and then use an index-matching fluid to reduce the visibility of debris on the board, as I did for a "Zipit Z2" board here: http://bealecorner.org/best/me.....in-oil.jpg )

Needless to say... please don't hurt your RasPi board this way- at least until they're in stock at the suppliers!

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AndrewS
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Re: We've just released the schematics!

Wed Apr 25, 2012 3:06 pm

Apologies for blowing my own trumpet, but I've made http://elinux.org/RPi_BCM2835_Pinout even more awesome

I've rotated the table so it matches the actual chip layout, and I've added colouring to the table so you can instantly see at-a-glance which GPIO pins aren't connected.

mole125
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Re: We've just released the schematics!

Wed Apr 25, 2012 3:12 pm

Andrew Scheller said:


Apologies for blowing my own trumpet, but I've made http://elinux.org/RPi_BCM2835_Pinout even more awesome

I've rotated the table so it matches the actual chip layout, and I've added colouring to the table so you can instantly see at-a-glance which GPIO pins aren't connected.


You've done some good work so feel free to blow your own trumpet.

Only think I wonder is whether you should swap the white and yellow so that if it is coloured it is connected and if it is plain white it is unconnected?  Or make the white a different colour (blue?)

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AndrewS
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Re: We've just released the schematics!

Wed Apr 25, 2012 3:23 pm

mole125 said:

Only think I wonder is whether you should swap the white and yellow so that if it is coloured it is connected and if it is plain white it is unconnected?  Or make the white a different colour (blue?)
I chose green for non-pins to resemble the "bare PCB" in the picture underneath, and yellow to resemble the empty "gold solder pad"

I decided not to colour the white cells in case it became a bit too "rainbow overload".

mole125
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Re: We've just released the schematics!

Wed Apr 25, 2012 3:37 pm

Look like I managed to slip in my edit to change green->blue in between you reading my response and quoting it!

I just found the white the least dominant colour and the yellow overly dominant when that is possibly the least important information, but it probably doesn't matter - especially now that you've updated the key to include white.

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AndrewS
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Re: We've just released the schematics!

Sat Apr 28, 2012 5:00 pm

Even more awesomeness...

I've copied the GPIO Alternative Functions table from BCM2835-ARM-Peripherals.pdf to the wiki http://elinux.org/RPi_BCM2835_GPIOs and made it fully hyper-linked and cross-referenced. And then added links to that from http://elinux.org/RPi_BCM2835_Pinout so that you can click on e.g. table cell E2 and then instantly see what other functions share that pin http://elinux.org/RPi_BCM2835_.....IOs#GPIO15

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