Communication between V5 Brain and Cortex

Hi, I am trying to figure out how to get a V5 Brain and a Cortex to talk to another for a side project.

The only way that I can think of, is by using a few of the 3 wire ports on the V5 Brain to send a signal to the digital ports on the Cortex.

I have a few ideas on how it would work, but in not sure on how to program it.