Datasheet
2010-2013 Microchip Technology Inc. DS40001452D-page 119
PIC16(L)F1516/7/8/9
12.5 PORTD Registers
(PIC16F1517/1519 only)
12.5.1 DATA REGISTER
PORTD is a 8-bit wide, bidirectional port. The
corresponding data direction register is TRISD
(Register 12-16). Setting a TRISD bit (= 1) will make the
corresponding PORTD pin an input (i.e., put the
corresponding output driver in a High-Impedance mode).
Clearing a TRISD bit (= 0) will make the corresponding
PORTD pin an output (i.e., enable the output driver and
put the contents of the output latch on the selected pin).
Example 12-1 shows how to initialize an I/O port.
Reading the PORTD register (Register 12-15) reads the
status of the pins, whereas writing to it will write to the
PORT latch. All write operations are read-modify-write
operations. Therefore, a write to a port implies that the
port pins are read, this value is modified and then written
to the PORT data latch (LATD).
12.5.2 DIRECTION CONTROL
The TRISD register (Register 12-16) controls the
PORTD pin output drivers, even when they are being
used as analog inputs. The user should ensure the bits in
the TRISD register are maintained set when using them
as analog inputs. I/O pins configured as analog input
always read ‘0’.
12.5.3 ANALOG CONTROL
The ANSELD register (Register 12-18) is used to
configure the Input mode of an I/O pin to analog.
Setting the appropriate ANSELD 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 ANSELD bits has no effect on digital out-
put functions. A pin with TRIS clear and ANSELD set will
still operate as a digital output, but the Input mode will be
analog. This can cause unexpected behavior when exe-
cuting read-modify-write instructions on the affected
port.
12.5.4 PORTD FUNCTIONS AND OUTPUT
PRIORITIES
PORTD has no peripheral outputs, so the PORTD
output has no priority function.
Note: The ANSELD bits default to the Analog
mode after Reset. To use any pins as
digital general purpose or peripheral
inputs, the corresponding ANSEL bits
must be initialized to ‘0’ by user software.