This is my first project with PIC33E, and both the devices will be connected by USB only.
Rpi will have a User Interface (written in Python) and which will enable the user to send and receive data.
PIC33E(planning to write the codes in objective C) will be connected to a bunch of sensors and few other PIC18 microcontrollers. Also, receive commands from Rpi and send it to PIC18 and send signals from the sensors to RPI.