I am toying with the idea of designing an Arduino form factor board using a 40 pin socket for PIC (or PICAXE) and 600mil DIL adapters with 300mil DIP sockets for 14, 20 & 28 pin PICs (or PICAXEs) that will plug in to the socket on the main board.

As far as possible I want to duplicate the capabilities and pin mapping (of functions, at least) of my Zarduino-40 designs as well as utilize all of the Zarduino (and other) shields. My Zarduino shields use both SPI and I2C which appears problematic for PBP as these share a pin on the PICs plus PBP3 still has no hardware support for either.

For PICAXE, if I use hardware for one and move the other to different pins and use software routines, the question is which one should I move? None of my I2C features are time critical so my inclination is to use software I2C but would like some input from the more experienced since most of my PIC usage has been with 8-pin devices in dedicated tasks.

If I do these, YourDuino.com will distribute them and they will undoubtedly prefer PICAXE code examples but the hardware might also be attractive to other PIC users.

What about an external crystal? Is one needed? There are numerous devices like WiFi-to-Serial that use RS232 but DT has indicated that the newer chips are fine with the internal oscillator. I use socketed crystals with Zarduino and am inclined to include sockets and caps for use with older chips.

I have just upgraded to PBP Gold but have yet to study it to see whether there are new features (or lack thereof) that might apply to this (nebulous) project.