Regarding interfacing the chipkit pi to the raspberry pi:
I'm sorry to be asking such a basic question, but as a newbie I simply can't find the answer.
One form of the question is -
what is the output voltage asserted on the Chipkit pi GPIO pins? Is it 5v0 or 3v3? And does it depend on whether or not the chipkit pi is powered from the Raspberry pi or is separately powered?
Another way (I hope, otherwise I'm lost) of asking an equivalent question is:
Is it electrically safe to connect the SPI pins on the chipkit's "Raspberry Pi breakout header" (pins 16, 18, 20 on J4) to the corresponding pins on the chipkit's "Digital/Serial Header" (pins 7, 9, 11 on JA1)?
And if not what circuitry is needed to allow the Rasperry Pi to safely read SPI signals (or indeed GPIO signals) sourced by the chipkit pi? Would a simple zener to drop a 5v0 signal to 3v3 be sufficient given the low power involved?
Or how about a couple of forward biased LEDs in series to drop 5v0 to 2v6? Using a 74LVC245 seems like overkill if it is not actually needed.
