I am designing a circuit connected to a simple open-close sensor, like a switch. For ease of construction, the circuit with the sensor switch closes to ground, and uses a 1 MΩ pullup resistor to Vcc to signal
HIGH when the switch is open.
I realize that power is flowing the entire time the switch is open, which may (or may not) drain the battery. Would it be more efficient to use a pulldown resistor to ground, and have the switch open to Vcc?
Tangentially, should there be a resistor on the connection to Vcc as well? Either to reduce current (save battery power) or prevent damage to the ATmega328?