USB Power Supply Arduino Shield

I want to start making some battery powered gadgets, but I really want to know how much power my circuits require before hooking up the battery and releasing them into the world.  After a bit of searching, I couldn’t find anything that would let me set my own voltage (sometimes 5V, sometimes 3.7V for batteries, sometimes something else), tell me how much current I’m using, and be cheap enough for a hobbyist like myself.  So I started drawing up a schematic.  This is what I think I can do:

– Switching regulator for good efficiency and up and down DC voltage conversion.  Highly considering LTC3112 to get a 3 to 12V range.

– Arduino shield.  This will give me lots of analog and digital I/Os.

– Can run off of the Arduino power or from an external power input.  Going to use an FDC6324 to switch between them.

– Current Sensing Circuit.

– Current Limit Circuit.  I don’t want to blow anything up with an accidental short.  I couldn’t find any integrated chips to handle the voltage range I want, to I’m going to use a power pFET.

– Programmable potentiometers so that everything can be set digitally.

I started drawing up a project in Kicad.  Here is the schematic so far usb_power.  Here is the project on Github.