I’m currently working on something that involves the Parallax PIR and Ping sensors. The main platform for this one is an Arduino Uno. Right now, Arduino has code on their website for both of these sensors, here and here. Since I thought that they’re both kinda messy, I wrote a library for each one, by just organizing the existing code. Credit goes to the original authors.
Here’s the link to the repository where they’re kept. If you’re not familiar with git, check out this link.