Adventures in Engineering Trade-Offs

Raspberry Pi Security Camera

Raspberry Pi Security Camera

Raspberry Pi Security Camera

I was contacted through the Boulder Hackerspace by someone who wanted help building a Raspberry Pi security camera.   We finally settled on the design being a cross between a PiLarm and system that sends pictures to your phone.

The hybrid system has:

  • 4×4 membrane keypad for issuing commands
  • Magnetic door sensor
  • PIR motion detector
  • 2×16 backlit LCD status display
  • WiFi module
  • And of course the the Raspberry Pi and Camera Module

I had a nice aluminum case that fit the display left over from a previous commercial design.

There where some “gotchas” in getting the Python code to work.  It was not possible to just mix and match code from the two reference designs.

  1. Sending the MMS picture does not work with Wheezy, but only with Jessie because Wheezy’s Python 2.7.3  is incompatible with the Twilio import. Jessie provides Python 2.7.9, which works.
  2. The magnetic door sensor and PIR motion detector code triggered interrupts.  This can interfere with the display code if not carefully structured.
  3. While a code block may work fine by itself, when you combine them you can put quite a demand on the processor.  Scanning the matrix keyboard left little time to do anything else.

However, when all was done and said, the final design did a great job of detecting motion or an opening of a door, then taking a picture and texting it to a phone.

A possible next step is to rework this system using a Banana Pi D1, once we can figure out how to reprogram it.