Datasheet

PIC17C7XX
DS30289C-page 84  1998-2013 Microchip Technology Inc.
10.6 PORTF and DDRF Registers
PORTF is an 8-bit wide bi-directional port. The corre-
sponding data direction register is DDRF. A '1' in DDRF
configures the corresponding port pin as an input. A '0'
in the DDRF register configures the corresponding port
pin as an output. Reading PORTF reads the status of
the pins, whereas writing to PORTF will write to the
respective port latch.
All eight bits of PORTF are multiplexed with 8 channels
of the 10-bit A/D converter.
Upon RESET, the entire Port is automatically config-
ured as analog inputs and must be configured in soft-
ware to be a digital I/O.
Example 10-6 shows an instruction sequence to initial-
ize PORTF. The Bank Select Register (BSR) must be
selected to Bank 5 for the port to be initialized. The fol-
lowing example uses the MOVLB instruction to load the
BSR register for bank selection.
EXAMPLE 10-6: INITIALIZING PORTF
FIGURE 10-13: BLOCK DIAGRAM OF RF7:RF0
MOVLB 5 ; Select Bank 5
MOVWF 0x0E ; Configure PORTF as
MOVWF ADCON1 ; Digital
CLRF PORTF, F ; Initialize PORTF data
; latches before
; the data direction
; register
MOVLW 0x03 ; Value used to init
; data direction
MOVWF DDRF ; Set RF<1:0> as inputs
; RF<7:2> as outputs
Data Bus
WR PORTF
WR DDRF
RD PORTF
Data Latch
DDRF Latch
P
V
SS
I/O pin
PCFG3:PCFG0
Q
D
QCK
Q
D
QCK
EN
QD
EN
N
ST
Input
Buffer
VDD
RD DDRF
To other pads
VAIN
CHS3:CHS0
To other pads
Note: I/O pins have protection diodes to VDD and VSS.