how write eeprom during power off time

[karthickiw]

hai,

i want to write my data during power off time. i try interrupt coding but it not work. interrupt coding is work only low to high. pls give solution for problem. i use 16F873A


by
E.karthic

[Ttelmah]

Direct use of the ordinary interrupt input, generally won't work, because it's detection level will actually start to drop as the supply rail falls. You need an external chip to do the detection, and trigger the interrupt. It can be done with a cheap comparator, or a monitoring IC, or (better), if the supply comes through a regulator, using a simple resistive divider, from the incoming supply before the regulator.

Best Wishes

[karthickiw]

sir,

give any circuit for produce the interrupts during supply off time.

by
E.karthic

[Ttelmah]

It is going to depend totally, on the nature of _your_ supply.
How is the regulated supply generated?.
What voltage is being used?.
What PIC is involved?.
What are it's operating voltage limits?.
How much data needs to be written?.
How frequent are interruptions likely to be?.
What ripple is present normally on the supply?.

Best Wishes