Project 022 – Greatly improved product

Redesign of a passive infrared motion detector

This project involved a redesign of a motion detector for office lighting applications. This manufacturer had a motion detector based on an analog circuit which was not good enough to modern standards. The analog circuit was rather sensitive to electromagnetic radiation as emitted from computer wireless networks, mobile phones and also from thunderstorms. The lights connected to this motion detector would sometimes inadvertently turn on.

The desire was not only to improve the EMC susceptibility but also to add new functionalities to the device at the same time.

The result was a more robust and enhanced version of this motion detector using digital signal processing (DSP). The EMC susceptibility was improved, the environment light level measurement was more accurate and the sound detection (which was used to keep the lights on when the occupants of an office were not directly in the view of the detector) was more sensitive.

A remote control option (with green status LED) was added to make the device suitable for application in offices where the was need to turn off the lights during presentations.

The electronic circuit was designed around the Microchip PIC16LF1824. The firmware was written in assembly language for best performance. A special motion detection algorithm was developed for this device.

The redesigned detector was thoroughly tested and many field tests were done to validate this product. Additional equipment was built and PC-software was written to perform these tests.