I'm trying to develop a cut wire detector that will be used in order to detect if a specific wire is broken or not (a.k.a fake bomb).
I'm using an ATMEGA328P running on batteries (3V) at the internal 8 Mhz clock. The external circuit used to detect the tamper loop, has this configuration:
In order to detect the state changes of the tamper loop, I'm using the
ISR INTERRUPTS of the atmega MCU, but with this configuration the resistor draws around 3/4 mA, also, when putting in a higher resistor (R1 = 100kΩ) the power consumption is too high (30/40 μA).
What do I need? I need to find a solution that allows me to monitor if the wire is cut (the wire lenght is around one meter) without using any additional power from the circuit, and keep the circuit running on battery power without the need to worry too much about the power consumption of the tamper monitoring circuit.
The target power consumption for the tamper circuit has to be lower than 100 nA.