You know me, I'm not powered by pure whimsy like some people. But I do really enjoy making things small (as evident by my quest for a Tiny Hexapod. So now I've got this crazy idea about making a tiny Arduino. Not an Arduino Mini or a Tinyduino, but a Tiny, to scale arduino.
Of course this is a bit impractical. There's no real benefit of having a smaller scaled Arduino, at lease in the prototyping sense, but it could be fun, so that's enough for me. So for a basis, I'm thinking that I could use 2mm headers instead of 2.54 mm headers .2 .54mm headers are used on a lot of standard prototyping hardware, since it's .1 inch - so everything from breadboards to components use this. 2mm tends to be for a little smaller stuff lie XBees. So just from the headers I've got a 22% size reduction - see the image for a mockup. That puts the total board length at 2.1 inches. If I cut off a little here and there, I could probably get it down to 2 inches. But can I get it smaller?
Digikey has these headers that are 1.27mm pitch - half the size! a Tiny 1.54 inch Arduino would be crazy. But at that point, do I actually have enough room to get all of the electronics on the board? I mean I can't just 'shrink' the circuitry like I did in the mock-up. I have a couple of things on my size (small surface mount chips, smaller usb, the fact that there's a lot of 'empty' room on the Uno) but it's still going to take some work. Not to mention finding eagle parts for those tiny connectors and making sure I can get them in smaller quantities, as they're somewhat less common.
My mom has a STEAM workshop next month, I'm thinking these could be cool badges. at 2 inches across, it's a little more reasonable to use them as actual Arduinos, at 1.54 it might be hard to find the right size pins to connect.
Really, I just need to spend some time in my PCB software, Eagle, and see how compact I can comfortably make the board, then pick my pins from there. Based on the Arduino mini and pro mini, I think I can get pretty small. I figure I'll go with a USB micro connector to keep things small. I might need to lose the ISP connector and just use wires to the side headers for programming the bootloader, but I'm not sure.
More importantly, what will I call it?