PIC16F913/914/916/917/946
3.1
ANSEL Register
3.0
I/O PORTS
The ANSEL register (Register 3-1) 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 PIC16F913/914/916/917/946 family of devices
includes several 8-bit PORT registers along with their
corresponding TRIS registers and one four bit port:
• PORTA and TRISA
• PORTB and TRISB
• PORTC and TRISC
• PORTD and TRISD(1)
• PORTE and TRISE
• PORTF and TRISF(2)
• PORTG and TRISG(2)
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.
Note 1: PIC16F914/917 and PIC16F946 only.
2: PIC16F946 only
PORTA, PORTB, PORTC and RE3/MCLR/VPP are
implemented on all devices. PORTD and RE<2:0>
(PORTE) are implemented only on the PIC16F914/917
and PIC16F946. RE<7:4> (PORTE), PORTF and
PORTG are implemented only on the PIC16F946.
REGISTER 3-1:
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: PIC16F914/PIC16F917/PIC16F946 only.
© 2007 Microchip Technology Inc.
DS41250F-page 43
MICROCHIP [ MICROCHIP ]
