Pictured below is a project we have completed for a retro-fit automatic folding car door mirror controller.

The car in question is a Japanese 4×4 with fold up mirrors and an after market OEM mirror switch fitted to raise and lower the mirrors when buttons are pressed in the vehicle. The goal of our controller is to automatically fold up the mirrors when the car is central locked, and to automatically fold down the mirrors when the car is central unlocked.

As things stood, when the ignition is on, if the fold up button is pressed, +12V is sent from the mirror switch to turn the two mirror motors in one direction, and if the fold down button is pressed, +12V is sent to turn the mirror motors in the other direction. Our controller sits between the mirror motors and the mirror switch and replicates this behaviour detecting the +12V signals and outputting the same to the mirrors for as long as a signal is present. But, when the ignition is off, there was no way to fold or unfold the mirrors.

When the car is central locked (ignition off) a +5V signal is present for one second on the wiring loom, and when it is unlocked another +5V signal is present. Our controller is designed to detect these signals, and if the ignition is off, to output +12V to turn the mirror motors in the required direction for a user programmable number of seconds immediately after detecting that the vehicle has been locked or unlocked. This gets the mirrors to automatically fold down ready for driving when the car is unlocked, and fold up out of harm’s way when the car is locked.

This controller was built around the ATmega328 microcontroller as a standalone Arduino project. Email neil@reuk.co.uk if you have an automotive electronics project of this type.