Microchip Technology ARD00385 Data Sheet
PIC18F87K90 FAMILY
DS39957D-page 276
2009-2011 Microchip Technology Inc.
REGISTER 20-3:
LCDREF: LCD REFERENCE VOLTAGE CONTROL REGISTER
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
R/W-0
LCDIRE
LCDIRS
LCDCST2
LCDCST1
LCDCST0
VLCD3PE
VLCD2PE
VLCD1PE
bit 7
bit 0
Legend:
R = Readable bit
R = Readable bit
W = Writable bit
U = Unimplemented bit, read as ‘0’
-n = Value at POR
‘1’ = Bit is set
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
LCDIRE:
LCD Internal Reference Enable bit
1
= Internal LCD reference is enabled and connected to the internal contrast control circuit
0
= Internal LCD reference is disabled
bit 6
LCDIRS:
LCD Internal Reference Source bit
If LCDIRE = 1:
1
1
= Internal LCD contrast control is powered by V
DDCORE
(3.3V) voltage
0
= Internal LCD contrast control is powered by V
DD
If LCDIRE = 0:
Internal LCD contrast control is unconnected. LCD band gap buffer is disabled.
Internal LCD contrast control is unconnected. LCD band gap buffer is disabled.
bit 5-3
LCDCST<2:0>:
LCD Contrast Control bits
Selects the Resistance of the LCD Contrast Control Resistor Ladder:
111
111
= Resistor ladder is at maximum resistance (minimum contrast)
110
= Resistor ladder is at 6/7th of maximum resistance
101
= Resistor ladder is at 5/7th of maximum resistance
100
= Resistor ladder is at 4/7th of maximum resistance
011
= Resistor ladder is at 3/7th of maximum resistance
010
= Resistor ladder is at 2/7th of maximum resistance
001
= Resistor ladder is at 1/7th of maximum resistance
000
= Minimum resistance (maximum contrast); resistor ladder is shorted
bit 2
VLCD3PE:
Bias 3 Pin Enable bit
1
= Bias 3 level is connected to the external pin, LCDBIAS3
0
= Bias 3 level is internal (internal resistor ladder)
bit 1
VLCD2PE:
Bias 2 Pin Enable bit
1
= Bias 2 level is connected to the external pin, LCDBIAS2
0
= Bias 2 level is internal (internal resistor ladder)
bit 0
VLCD1PE:
Bias 1 Pin Enable bit
1
= Bias 1 level is connected to the external pin, LCDBIAS1
0
= Bias 1 level is internal (internal resistor ladder)