I have already a vehicle that drives very good with the arduino mega 2560. The next step in my project is to drive the vehicle on a gps that communicates with the arduino. Suppose that the arable land in the form is of a trapezium and that I have the coordinates of the 4 corners. The goal of my project is to assure that the vehicle stays in the trapezium. Is there someone who can help me with that? To give me some code and tell me which GPS is the most suitable for this? I want to excuse me that my English isn't very well. I understand everything, but I'm not good in writing.