Depending on how you view them, red light cameras are a great way to get people to drive carefully, or an utter nuisance. We agree with the latter opinion, as does [Dave], so he built a handy little device that alerts him when he’s about to approach one of these intersections.
His Red Light Camera Alerter is based around an Atmega 328P sporting the Arduino bootloader. The micro obtains GPS coordinates while [Dave] is driving, comparing his current location with a table of all known red light intersections in the area. As he nears a red light camera, the status LED changes colors from blue to yellow to red as he gets closer, making it easy to keep aware of his situation. He also included an Adafruit OLED display in his device, which relays his speed, GPS coordinates, heading, and actual distance from the red light in real time.
While [Dave] admits that he doesn’t really have a need for the alerter as there are only a couple located in his immediate vicinity, he says it was a fun and easy way to get some experience with using GPS sensors in his projects. He doesn’t have any video of it in action, but you can find the code he uses to drive the alerter on his blog.