Configuring alert for intruder detection system

In the lecture video in configuring hardware for intrusion detection system, In the video it was said that if condition when digital pin 1 = 0,the sensor will be triggered when 0 is output(the video thumbnail around 0:45),but in the note given down the video, it is said that alert condition must be given for digital pin 1 as output 1 for triggering… I am confused here. Which one should be considered?

Hi @a.atul2018,

I am inviting @vinayak.joshi to help you out with this query.