Monitor supply voltage of chip?

[robbo78]

@robbo78
That solution is not good for battery.
With zener regulator current draw from battery is same in if pic is sleep mode as in run mode.
If you use zener, then feed that voltage into analog pin, and then do ADC. This way current thru zener can be few uA instead few mA.

Good idea! I have just found this part which is a bit of a "cheat", and quite cheap? - http://www.farnell.com/datasheets/1669371.pdf

EDIT: Just realised that "amgen" already stated this

microchip has a to92 voltage detector...... different voltages and draws 1 microamp....
http://ww1.microchip.com/downloads/e...Doc/21434g.pdf