August 10, 2015: I spent a bit too much time modeling the board in EAGLEUP, but it looks nice. It also made me think about a few things. First, there are a lot of components on this circuit, and I am going to need to think about what can be removed in a more finalized version. First, the TDK pressure sensor die is much smaller than the SO8 package on this prototype. The bypass caps on the unused power supplies can probably be removed as well. The reprogramming header and the RST pullup can probably be removed when reprogramming through the RFID reader is working (it is possible with this micro). It might even be possible to eliminate the op amp if the reduced resolution is adequate for normal use.

One other thing I thought of is that if this is going to go on a low cost printed circuit with conductive ink (like a standard cheap RFID tag), the vias will need to go. That will be pretty hard to do, so I'm going to leave that one alone for right now. I'll have to come back to it after the first generation of prototypes on rigid boards are working.