P0.0:       KEY
P1.0 .7:    PAD
    1: VFD segments to be display
        1.1: only segments in grid G1+G4(default)
        1.2: all segments only
    2: VFD flashing
        2.1: all displayed segments continuously ON(default)
        2.2: display segments partially ON in roation mode(segments P1 to P8 ON for 10s
             ,then segments P9 to P15 ON for the next 10s,then P1 to P8 ON again and so on)
    3: filament voltage
        3.1: 3.2V(default)
        3.2: 3.1V
        3.2: 3.0V
        3.4: 2.9V
        3.5: 2.8V
        3.6: 2.6V
    4: Pulse width setting for VFD driver
        4.1: 14/16 duty(default)
        4.2: 13/16 duty
        4.3: 12/16 duty
        4.4: 11/16 duty
        4.5: 10/16 duty
    5:Grid and anode(segment) voltage
        5.1: grid = 25V,anode = 30V(default)
        5.2: grid = 23V,anode = 28V
        5.3: grid = 20V,anode = 25V
        
P2.0:   VFD.DOUT
P2.1:   VFD.STB
P2.2:   VFD.DIN
P2.3:   VFD.CLK