Add some pads so SPI can be jumper selected from Uno's D10-11-12-13, or have wires brought over from Mega's 50-51-52-53 (or whatever they are) for max flexibility.
What are some of the most popular shields today?
If you're new to Arduino, don't try to design a new product that will work for each and every person in the the world as a first project.Start by building something simple but fun that you can learn from instead.
...and they use the same pins (SPI + pin 4).
If the boards all use the same header, then shield compatibilty is sort of built in, yes?Uno/Leonardo have same header assignments, Mega has all the extra pins plus SPI in a different place. Add some pads so SPI can be jumper selected from Uno's D10-11-12-13, or have wires brought over from Mega's 50-51-52-53 (or whatever they are) for max flexibility. Same header pins can be used, Mega needs D20-21-22-23 (whatever those are) set to inputs so 50-51-52-53 are not interfered with.
When you design Arduino shields, do you typically target a specific Arduino board (e.g. Uno) or try to make it compatible with as many boards as possible? e.g. Uno, Leonardo, Mega2560...I'm also curious about the number of people with each type of Arduino board, i.e. market share, if anyone has that info.