Just received a Fio and have it running with an xbee. I looked over the schematic but am still abit confused.
Is there a pin capable of giving the battery voltage with a simple analogread?
I would like to be able to show this on an lcd to know when the 2000mah lipo needs charging.
Hi DAS.
Yes, there’s a voltage divider across the battery leads that has it’s output connected to A10 (PD6) on the ATmega chip. The voltage divider is setup so that the Fio will see 1/2 the actual battery voltage.
Hope this helps!
Thanks Chris.
I have another question. It says in the hook up guide you can pull the reset low and shut the fio off and back high to perform a reset. Will the board still charge the battery if plugged in to usb if the reset is pulled low?
Id like to be able to turn the board off while it charges the battery with a switch on the outside of an enclosure.
Hello DAS.
Pulling reset low doesn’t technically turn the board off, it just puts the microcontroller on the board into reset and it won’t execute any code in that state. (It appears to be off, but is still drawing a small amount of current.)
Battery charging should still work while the board is in reset though since charging isn’t a function that requires the microcontroller to work. Additionally, you really don’t need to pull reset high to turn things back on, just don’t pull it low and it will restart. There’s a pullup resistor built in that will pull reset high for you when it’s not being pulled low externally. 
Understood.
What I want to do is mount the fio inside an enclosure and have the ability to turn it off/on via an external switch.
Is there a way to by pass the onboard off/on switch without having to desolder and remove it and then add wires to the external switch to take its place?
No worries I did some reading and found what I needed.
Thanks