How to connect PIR sensors with a shift register

Hi all,

i am doing a project , in that i need to connect 8 PIR sensors to my arduino , but i have 4 pins left in board .So i thought to connect those PIR sensors to a shift register (parallel in serial out).How can i connect these sensors to 74HC595 shift register to read the values.

595 ICs are good for output (serial in parallel out) from the Arduino. You probably need to look at a 165 for inputs (parallel in, serial out). Same concept, just the opposite direction.

Lots of examples of how to use this if you consult Mr Google.