So we were building this thing with a raspberry pi, a few sensors and a few motors but for some reason we could not interface a sensor with the pi (this is supposed to be trivial) so we interfaced it with an Arduino and had connected a pin on the Arduino to the Raspberry pi to alert the pi when the sensor reads something!

Not something we were proud of but we had time constraints and couldn't figure out how to make it work. Also, the thing we were building was just for a one time use so we thought it would be okay