PIC16F707 Datasheet, PDF (62/284 Pages) Microchip Technology – 40/44-Pin, Flash Microcontrollers with nanoWatt XLP and mTouch™ Technology

PIC16F707/PIC16LF707
6.5 PORTD and TRISD Registers
PORTD is a 8-bit wide, bidirectional port. The
corresponding data direction register is TRISD
(Register 6-14). 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 6-4 shows how to initialize PORTD.
Reading the PORTD register (Register 6-13) 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.
The TRISD register (Register 6-14) 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’.
EXAMPLE 6-4: INITIALIZING PORTD
BANKSEL PORTD
CLRF PORTD
BANKSEL ANSELD
CLRF ANSELD
BANKSEL TRISD
MOVLW B‘00001100’
MOVWF TRISD
;
;Init PORTD
;Make PORTD digital
;
;Set RD<3:2> as inputs
;and set RD<7:4,1:0>
;as outputs
6.5.1 ANSELD REGISTER
The ANSELD register (Register 6-15) 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 affect on digital
output 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:
The ANSELD register must be initialized
to configure an analog channel as a digital
input. Pins configured as analog inputs will
read ‘0’.
REGISTER 6-13: PORTD: PORTD REGISTER
R/W-x
RD7
bit 7
R/W-x
RD6
R/W-x
RD5
R/W-x
RD4
R/W-x
RD3
R/W-x
RD2
R/W-x
RD1
R/W-x
RD0
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
RD<7:0>: PORTD General Purpose I/O Pin bits
1 = Port pin is > VIH
0 = Port pin is < VIL
DS41418A-page 62
Preliminary
 2010 Microchip Technology Inc.