For extra credit, you can use two robots, and coordinate their actions by sending messages. For an example of how to use LNP, the Lego Networking Protocol, see bytedance1.c and bytedance2.c. Note that all Mindstorms, by default, have address 0 (this default can be changed by recompiling legOS, but maybe don't do it for this assignment). You can distinguish who is the intended recipient of a packet by using port numbers as addresses. Note that port number 0 is reserved by the legOS loader. Valid port numbers are thus 1..15.