PIC power backup with "super capacitor"
Hello,
I need to make a power backup for a PIC.
As it is a mains's frequency driven clock and thus powered by the mains too. In case of power loss, I want to make the PIC go on by itself on a backup power source and keep on counting "time" until mains power comes back again.
The anything it will do during it's backup mode will be to keep the PIC essential function "alive" to count interrupts. Any other display or buzzer will be shut off.
I think I can use a 5,5V super capacitor (to keep it as small as possible).
Since I'm not an electronician, I don't really know what capacity I should use if I want to make sure my PIC will stay running for, lets say, 2 hours (never seen a son long power outage in my country... should be the worst case).
I have found a datasheet about one of these caps and I can choose between 6 capacities.
1) Witch one shall I take?
2) I've read my 16F88 ds about low power consumption. These are "physical" tips. What about software? What is the best way to program my PIC this way?
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