PIC18F23K20 Datasheet, PDF (279/420 Pages) Microchip Technology – 28/40/44-Pin Flash Microcontrollers with 10-Bit A/D and nanoWatt Technology

PIC18F2XK20/4XK20
20.8 Additional Comparator Features
There are two additional comparator features:
• Simultaneous read of comparator outputs
• Internal reference selection
20.8.1 SIMULTANEOUS COMPARATOR
OUTPUT READ
The MC1OUT and MC2OUT bits of the CM2CON1
register are mirror copies of both comparator outputs.
The ability to read both outputs simultaneously from a
single register eliminates the timing skew of reading
separate registers.
Note 1: Obtaining the status of C1OUT or C2OUT
by reading CM2CON1 does not affect the
comparator interrupt mismatch registers.
20.8.2 INTERNAL REFERENCE
SELECTION
There are two internal voltage references available to
the non-inverting input of each comparator. One of
these is the 1.2V Fixed Voltage Reference (FVR) and
the other is the variable Comparator Voltage Reference
(CVREF). The CxRSEL bit of the CM2CON register
determines which of these references is routed to the
Comparator Voltage reference output (CXVREF). Fur-
ther routing to the comparator is accomplished by the
CxR bit of the CMxCON0 register. See Section 21.1
“Comparator Voltage Reference” and Figure 20-2
and Figure 20-3 for more detail.
REGISTER 20-3: CM2CON1: COMPARATOR 2 CONTROL REGISTER 1
R-0
R-0
R/W-0
R/W-0
U-0
U-0
U-0
MC1OUT MC2OUT C1RSEL C2RSEL
—
—
—
bit 7
U-0
—
bit 0
Legend:
R = Readable bit
-n = Value at POR
W = Writable bit
‘1’ = Bit is set
U = Unimplemented bit, read as ‘0’
‘0’ = Bit is cleared
x = Bit is unknown
bit 7
bit 6
bit 5
bit 4
bit 3-0
MC1OUT: Mirror Copy of C1OUT bit
MC2OUT: Mirror Copy of C2OUT bit
C1RSEL: Comparator C1 Reference Select bit
1 = FVR (1.2 Volt fixed voltage reference) routed to C1VREF input
0 = CVREF routed to C1VREF input
C2RSEL: Comparator C2 Reference Select bit
1 = FVR (1.2 Volt fixed voltage reference) routed to C2VREF input
0 = CVREF routed to C2VREF input
Unimplemented: Read as ‘0’
© 2007 Microchip Technology Inc.
Advance Information
DS41303B-page 277