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Raspberry Pi, PyFace Digital, the lost documentation, I found it finally

The Raspberry PI or R-pi from is well known these days.
It is not an accident that I have one, I have been doing Linux stuff since 1991, and professionally since 1996 I can not skip over these developments, have to keep up with the new kids. :-)
Times have changed, hardware has become very affordable, everybody knows the Arduino, Raspberry Pi and Beagle-Bone-Black (BBB). Not everybody knows the stuff that aka Acme-Systems and aka Olimex make, so I will endorse them here.
Since I am an engineer I expect to connect switches and relays to the boards and some documentation with products, not so with the "PiFace Digital" board, it comes without serious documentation, not a even the schematic. All links on their blog point nowhere. People asked them many times, yet nowhere is the schematic to be found.

I finally found some info after hours of google-work, someone made a copy!
So I quickly copied that and put it here for you to find, that is the reason you are here right?
Here is a picture.
Pi Face digital schematic

Have fun with it.
I will report adventures with the board when I get time.


Update: this schematic is for an old board, look at JP3, where does it go? Are the INTA INTB not connected to a GPIO pin, what is that?, do we have to poll the 16-bit I/O Port Expander (mcp23s17) to see if there is a pin toggled. If that is the case this board is an example of how NOT to design an IO board.


Update 23 aug 2013
I sent a mail to pi AT

And I got a prompt reply:

Hi Edwin,
Unfortunately the schematics are not available however if you're looking to use interrupts then the new software supports them.

You can find the most up-to-date Python libraries for PiFace Digital here:
And here is some documentation on how to use interrupts:

Pins INTA (20) and INTB (19) are both wired to GPIO pin 25.

Hope that helps!


So things are not as bad as they seemed. I will update the schematic picture above to reflect the new information today.
After measuring the connections, I found that INTB is connected to GPIO25 (pin 22 on the connector, in the schematic it is marked GPIO6) but INTA is just not connected.


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