
PIC18F1230/1330
DS39758D-page 184
2009 Microchip Technology Inc.
REGISTER 18-1:
CVRCON: COMPARATOR VOLTAGE REFERENCE CONTROL REGISTER
R/W-0
U-0
R/W-0
CVREN
—
CVRR
CVRSS
CVR3
CVR2
CVR1
CVR0
bit 7
bit 0
Legend:
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
CVREN
: Comparator Voltage Reference Enable bit
1
=CVREF circuit powered on
0
=CVREF circuit powered down
bit 6
Unimplemented:
Read as ‘0’
bit 5
CVRR
: Comparator VREF Range Selection bit
1
= 0 to 0.667 CVRSRC, with CVRSRC/24 step size (low range)
0
= 0.25 CVRSRC to 0.75 CVRSRC, with CVRSRC/32 step size (high range)
bit 4
CVRSS
: Comparator VREF Source Selection bit
When CVRR = 1
1
= Comparator reference source, CVRSRC = (VREF+) – (AVSS)
0
= Comparator reference source, CVRSRC = AVDD – AVSS
When CVRR = 0
1
=VREF+ input used directly, comparator voltage reference bypassed
0
= No reference is provided
bit 3-0
CVR3:CVR0:
Comparator VREF Value Selection bits (0
(CVR3:CVR0) 15)
When CVRR = 1:
CVREF = ((CVR3:CVR0)/24)
(CVRSRC)
When CVRR = 0:
CVREF = (CVRSRC/4) + ((CVR3:CVR0)/32)
(CVRSRC)