Datasheet

 2010-2012 Microchip Technology Inc. DS41413C-page 121
PIC12(L)F1822/PIC16(L)F1823
12.0 I/O PORTS
Depending on the device selected and peripherals
enabled, there are up to two ports available. In general,
when a peripheral is enabled, that pin may not be used
as a general purpose I/O pin.
Each port has three standard registers for its operation.
These registers are:
• TRISx registers (data direction)
• PORTx registers (reads the levels on the pins of
the device)
• LATx registers (output latch)
Some ports may have one or more of the following
additional registers. These registers are:
• ANSELx (analog select)
• WPUx (weak pull-up)
• INLVLx (input level control)
The Data Latch (LATx registers) is useful for
read-modify-write operations on the value that the I/O
pins are driving.
A write operation to the LATx register has the same
affect as a write to the corresponding PORTx register.
A read of the LATx register reads of the values held in
the I/O PORT latches, while a read of the PORTx
register reads the actual I/O pin value.
Ports with analog functions also have an ANSELx
register which can disable the digital input and save
power. A simplified model of a generic I/O port, without
the interfaces to other peripherals, is shown in
Figure 12-1.
FIGURE 12-1: GENERIC I/O PORT
OPERATION
TABLE 12-1: PORT AVAILABILITY PER
DEVICE
Device
PORTA
PORTC
PIC12(L)F1822 ●
PIC16(L)F1823 ●●
QD
CK
Write LATx
Data Register
I/O pin
Read PORTx
Write PORTx
TRISx
Read LATx
Data Bus
To peripherals
ANSELx
VDD
VSS