PIC16F882/883/884/886/887
3.2
Additional Pin Functions
RA0 also has an Ultra Low-Power Wake-up option. The
next three sections describe these functions.
3.2.1
ANSEL REGISTER
The ANSEL register (Register 3-3) is used to configure
the Input mode of an I/O pin to analog. Setting the
appropriate ANSEL bit high will cause all digital reads
on the pin to be read as ‘0’ and allow analog functions
on the pin to operate correctly.
The state of the ANSEL bits has no affect on digital out-
put functions. A pin with TRIS clear and ANSEL set will
still operate as a digital output, but the Input mode will
be analog. This can cause unexpected behavior when
executing read-modify-write instructions on the
affected port.
REGISTER 3-3:
ANSEL: ANALOG SELECT REGISTER
R/W-1
ANS7(2)
bit 7
R/W-1
ANS6(2)
R/W-1
ANS5(2)
R/W-1
ANS4
R/W-1
ANS3
R/W-1
ANS2
R/W-1
ANS1
R/W-1
ANS0
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 7-0
ANS<7:0>: Analog Select bits
Analog select between analog or digital function on pins AN<7:0>, respectively.
1= Analog input. Pin is assigned as analog input(1)
0= Digital I/O. Pin is assigned to port or special function.
.
Note 1: Setting a pin to an analog input automatically disables the digital input circuitry, weak pull-ups, and
interrupt-on-change if available. The corresponding TRIS bit must be set to Input mode in order to allow
external control of the voltage on the pin.
2: Not implemented on PIC16F883/886.
DS41291D-page 40
Preliminary
© 2007 Microchip Technology Inc.
MICROCHIP [ MICROCHIP ]
