The next version of the clock will have the tenth digit added, and will have the PPS signal connected to the ICP pin rather than the INT0 pin. The INT0 pin was chosen back when there was no timer being used, but as soon as I added the button debounce code, that stopped being true. And then came the interpolation of the tenths and suddenly it was a good idea.

Also for v2 the LDO will be replaced with the SC189Z buck converter I've been using in the OCXO variant of my GPSDO. It turns out that we're really pushing the limits of the SOT23-5 LDOs I've been using. I started down the road of upgrading to a beefier LDO in an SOT-225 footprint, but then remembered how nice the SC189Z is. We get a nice efficiency boost for adding only a net single component to the board (the inductor for the buck converter), and the power supply becomes rated for upwards of an amp without thermal issues.