coffee-roaster-software with Arduino

This repository is for a DiY Drum coffe raoster.
(photo) The project I want to make is beginning with a very simple structure of Software and Hardware. It is a PID control Temp of a grill ( rotisserie), that I have transformed it into a basic coffe-roaster. It has a metal mesh drum, which is rotated by a 220VAC electric motor (15rot/min) The heat is provided by 4 resitences,600W each, the value of two of them is controled,with a SSR connected at a PWM output of the Arduino. (photo) The temperature is measured with a K type thermocouple, and a Max6675 shield connected at a analog input of the Arduino. (photo) I have only one sensor for the moment, just for the IT (Internal Temperature), but it will be a BT( Bean Temperature) in the future too. No forced ventilation for the moment, but it will be. The electric motor will be a variable speed controled