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

The Raspberry PI or R-pi from http://www.raspberrypi.org/ 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 http://www.acmesystems.it/ aka Acme-Systems and https://github.com/OLIMEX/OLINUXINO 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.

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 cs.man.ac.ukAnd 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: https://github.com/piface/pifacedigitalio

And here is some documentation on how to use interrupts: http://piface.github.io/pifacedigitalio/example.html#interrupts

The datasheet for the MCP23S17: http://ww1.microchip.com/downloads/en/devicedoc/21952b.pdf

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

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