Microchip Technology IC PIC MCU PIC16F1937-I/PT TQFP-44 MCP PIC16F1937-I/PT Data Sheet
Product codes
PIC16F1937-I/PT
PIC16(L)F1934/6/7
DS41364E-page 144
2008-2011 Microchip Technology Inc.
12.5
PORTD Registers
). 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).
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).
shows how to initialize an I/O port.
Reading the PORTD register (
) 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).
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).
The TRISD register (
) 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’.
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’.
12.5.1
ANSELD REGISTER
The ANSELD register (
) 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
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.
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
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.
12.5.2
PORTD FUNCTIONS AND OUTPUT
PRIORITIES
PRIORITIES
Each PORTD pin is multiplexed with other functions. The
pins, their combined functions and their output priorities
are shown in
pins, their combined functions and their output priorities
are shown in
.
When multiple outputs are enabled, the actual pin
control goes to the peripheral with the highest priority.
Analog input and some digital input functions are not
included in the list below. These input functions can
remain active when the pin is configured as an output.
Certain digital input functions override other port
functions and are included in
control goes to the peripheral with the highest priority.
Analog input and some digital input functions are not
included in the list below. These input functions can
remain active when the pin is configured as an output.
Certain digital input functions override other port
functions and are included in
Note:
PORTD is available on PIC16(L)F1934
and PIC16(L)F1937 only.
and PIC16(L)F1937 only.
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.
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.
TABLE 12-9:
PORTD OUTPUT PRIORITY
Pin Name
Function Priority
(1)
RD0
COM3 (LCD)
RD0
RD0
RD1
CCP4 (CCP)
RD1
RD1
RD2
P2B (CCP)
RD2
RD2
RD3
SEG16 (LCD)
P2C (CCP)
RD3
P2C (CCP)
RD3
RD4
SEG17 (LCD)
P2D (CCP)
RD4
P2D (CCP)
RD4
RD5
SEG18 (LCD)
P1B (CCP)
RD5
P1B (CCP)
RD5
RD6
SEG19 (LCD)
P1C (CCP)
RD6
P1C (CCP)
RD6
RD7
SEG20 (LCD)
P1D (CCP)
RD7
P1D (CCP)
RD7
Note 1:
Priority listed from highest to lowest.