Project 027 – Improving a product

Redesign of a small passive infrared motion detector PCB

This project involved the redesign of a small motion detector PCB for OEM automotive applications. The original analog circuit was too sensitive to electromagnetic radiation and vehicle power supply noise.

A redesign was made with digital signal processing (DSP) for improved EMC susceptibility and with improved power supply noise immunity. The electronic circuit was designed around the Microchip PIC12LF1822 with firmware written in assembly language. A special motion detection algorithm was developed for this device. The result was a more robust version of this motion detector. A potentiometer on the PCB was used to set the on-time of the light output.

The redesigned detector was thoroughly tested using a PC-interface and measurement software.

Additionally, a production tester for manual operation was built.