PIC18F24J10-E/ML MICROCHIP [Microchip Technology], PIC18F24J10-E/ML Datasheet - Page 95

• Manufacturer Part Number: PIC18F24J10-E/ML
• Description: 28/40/44-Pin High-Performance RISC Microcontrollers with nanoWatt Technology
• Manufacturer: MICROCHIP [Microchip Technology]

9.0
Depending on the device selected and features
enabled, there are up to five ports available. Some pins
of the I/O ports are multiplexed with an alternate
function from the peripheral features on the device. In
general, when a peripheral is enabled, that pin may not
be used as a general purpose I/O pin.
Each port has three registers for its operation. These
registers are:
• TRIS register (data direction register)
• Port register (reads the levels on the pins of the
• LAT register (output latch)
The Data Latch (LAT register) is useful for read-modify-
write operations on the value that the I/O pins are
driving.
A simplified model of a generic I/O port, without the
interfaces to other peripherals, is shown in Figure 9-1.
FIGURE 9-1:
© 2007 Microchip Technology Inc.
device)
RD LAT
Data
Bus
WR LAT
or Port
WR TRIS
RD TRIS
RD Port
Note 1:
I/O PORTS
I/O pins have diode protection to V
TRIS Latch
Data Latch
D
D
CK
CK
GENERIC I/O PORT
OPERATION
Q
Q
Q
EN
EN
D
DD
and V
I/O pin
Buffer
Input
SS
.
(1)
Preliminary
PIC18F45J10 FAMILY
9.1
When developing an application, the capabilities of the
port pins must be considered. Outputs on some pins
have higher output drive strength than others. Similarly,
some pins can tolerate higher than V
9.1.1
The output pin drive strengths vary for groups of pins
intended to meet the needs for a variety of applications.
PORTB and PORTC are designed to drive higher
loads, such as LEDs. All other ports are designed for
small loads, typically indication only. Table 9-1 sum-
marizes the output capabilities. Refer to Section 23.0
“Electrical Characteristics” for more details.
TABLE 9-1:
9.1.2
The voltage tolerance of pins used as device inputs is
dependent on the pin’s input function. Pins that are used
as digital only inputs are able to handle DC voltages up
to 5.5V; a level typical for digital logic circuits. In contrast,
pins that also have analog input functions of any kind
can only tolerate voltages up to V
beyond V
summarizes
Section 23.0 “Electrical Characteristics” for more
details.
TABLE 9-2:
PORTA
PORTD
PORTE
PORTB
PORTC
PORTA<5:0>
PORTB<5:0>
PORTC<1:0>
PORTE<2:0>
PORTB<7:6>
PORTC<7:2>
PORTD<7:0>
Port or Pin
Port
I/O Port Pin Capabilities
DD
PIN OUTPUT DRIVE
INPUT PINS AND VOLTAGE
CONSIDERATIONS
on these pins should be avoided. Table 9-2
Minimum Intended for indication.
the
Drive
High
OUTPUT DRIVE LEVELS
INPUT VOLTAGE LEVELS
Tolerated
Input
input
5.5V
V
DD
Suitable for direct LED drive
levels.
capabilities.
Only V
tolerated.
Tolerates input levels
above V
most standard logic.
DD
Description
. Voltage excursions
Description
DS39682C-page 93
DD
DD
DD
input levels.
input levels
, useful for
Refer
to