Controller Advantages:

Diagnostic Function embedded:

Image that the grill is interrupted suddenly when lord collects all people for the party. The function of diagnostic is to figure the problem there out and get spare parts in quick way. 

The theory is to use sensor to detect motor, fan and hot rod running in normal condition. The controller will give an alarm if any failures. 

PID Algorithm:

A proportional–integral–derivative controller (PID controller or three term controller) is a control loop feedback mechanism requiring continuously modulated control. A PID controller continuously calculates an error value e(t) as the difference between a desired setpoint (SP) and a measured process variable (PV) and applies a correction based on proportional, integral, and derivative terms. 

The advantage PID again time control is to control temperature in more stable and less impacted by wood pellets, grill size, grill mechanical design, environment etc.

WIFI plus Bluetooth TFT Screen:

Which functionalities allow end users control grill in remote way and display whatever users want to display.