Most PIR modules have a pot that sets the timing, and can be changed to have it time out after a few minutes or so. That should help already.
A 555 monostable is another option, that would basically take over the timing of the Arduino.
Most PIR modules have a pot that sets the timing, and can be changed to have it time out after a few minutes or so. That should help already.
A 555 monostable is another option, that would basically take over the timing of the Arduino.