|Created||March 03, 2013|
|Last modified||August 05, 2013|
Arduino Pro Mini 5v based car alarm - Microwave motion detection
Arduino Pro Mini 5v based. Uses a usb car charger for power. Motion sensor is a 12v microwave sensor typical of car alarms and found on eBay. The sensor has a negative trigger so no signal level adjustment is needed.
I wanted to avoid needing a key chain remote so it arms automatically 10 minutes after the car is turned off. The alarm can be disarmed by turning the key in the ignition to accessory or by pushing a hidden button. The code allows for a few detections before beeping (and eventually honking) so it won't go off before you get to disarm it.
The Arduino sleeps for two seconds between LED blinks to conserve power. The sensor and a push button both serve as interrupts so it is still responsive during the sleep period. It uses 11mA while sleeping and 17mA while active.
Thanks to Nick Gammon for his guide on Arduino sleep options
Note: I used a 5v car usb charger as the voltage regulator. I tried a few until I found one that was efficient enough to meet my needs.
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