The functions of the control panel cpu is:
-Monitoring the key inputs.
It communicates the keypad and function key inputs to the CPU on the main controller PCB.
-Monitoring the Touch panel input.
It communicates the key input made on the touch panel to the CPU on the main controller PCB.
-Controlling the Buzzer sound.
-Controlling the control panel LED.
The colour LCD is driven by main controller and the control panel CPU PCB serves to relay the drive signals.