Power input connector

The only allowed input voltage is 5VDC.  R1 had a JST-XH connector, which left a lot of room for erroneous connections: higher voltages than 5V and reverse power connection.  If we replace it with a micro-usb connector instead (Amphenol 10118192-0002LF), then it's clear for anyone how to connect it, where to connect it to and what supply voltage it's using.

I don't like to see a micro-usb connector as a user interface connector because it's quite brittle.  Luckily Sparkfun has us covered here.  There's a Panel Mount USB-B to Micro-B Cable for $2.50.

By using the micro-USB connector, we could leave out the reverse polarity, over voltage protection and over current protection.  The USB 5V power source will have these protections built in.

Extra buck-boost converter

This allows an extra output voltage, up to around 12V.

Power output connectors

The JST-XH connectors are too big for this small board.  They have been replaced by JST-PH.