Yeah, a universal and cheap level shifter is a Holy Grail, but I think that is hard to do. For general digital I/O it should work fine, more tricky stuff like I2C and analog may be hard to convert reliably, and for low cost.
If you add the fact that pin functions move about between processors, in theory you might need to be able to map every pin as straight through, level conversion with pullup, level w/o pullup, analog in, analog out... gets complicated. There is regular discussion on the topic on the Arduino Due forum, and there is really no universal low cost answer.
Offsetting the pins so they can use through hole connectors works for Uno, but not for Mega. I have only seen mention of Uno shields, which I guess the majority of shields are, I am not sure we will see a similar converter board for Mega, since it is more expensive to do and a smaller market.
The RAMPS converter I and others have been working on is application specific, so can be simplified, but even there it is perhaps not very cost-effective.
If you add the fact that pin functions move about between processors, in theory you might need to be able to map every pin as straight through, level conversion with pullup, level w/o pullup, analog in, analog out... gets complicated. There is regular discussion on the topic on the Arduino Due forum, and there is really no universal low cost answer.
Offsetting the pins so they can use through hole connectors works for Uno, but not for Mega. I have only seen mention of Uno shields, which I guess the majority of shields are, I am not sure we will see a similar converter board for Mega, since it is more expensive to do and a smaller market.
The RAMPS converter I and others have been working on is application specific, so can be simplified, but even there it is perhaps not very cost-effective.
