The multicamera setup

It may have occurred to you that the Raspberry Pi has only one camera module input. Now, this is obviously limiting if you want to have multiple cameras around your property that are triggered by motion detectors.

However, there is nothing stopping us from building standalone units that have a separate Raspberry Pi board with a PIR detector, Camera Module, and network connection, either using a Wi-Fi dongle or Ethernet.

Because you only need a single input to the Raspberry Pi to detect when the PIR motion sensor is triggered, you can use the on-board GPIO port to connect the sensor, rather than using a port expander. The Raspberry Pi will email the alert over the network, and could alert the main controller Pi if required—making it a slave sensor device.

You can readily obtain small PIR detectors, such as the Parallax one shown next, which you can mount onto a Raspberry Pi Case along with the camera module, creating a self-contained unit.

A Parallax PIR motion sensor (type...