Datasheet

 2009 Microchip Technology Inc. Preliminary DS41364D-page 129
PIC16F193X/LF193X
12.0 I/O PORTS
Depending on the device selected and peripherals
enabled, there are up to five 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 registers for its operation. These
registers are:
• TRISx registers (data direction register)
• PORTx registers (reads the levels on the pins of
the device)
• LATx registers (output latch)
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
12.1 Alternate Pin Function
The Alternate Pin Function Control (APFCON) register
is used to steer specific peripheral input and output
functions between different pins. The APFCON register
is shown in Register 12-1. For this device family, the
following functions can be moved between different
pins.
•SS
(Slave Select)
• P2B output
• CCP2/P2A output
• CCP3/P3A output
• Timer1 Gate
• SR Latch SRNQ output
• Comparator C2 output
These bits have no effect on the values of any TRIS
register. PORT and TRIS overrides will be routed to the
correct pin. The unselected pin will be unaffected.
QD
CK
Write LATx
Data Register
I/O pin
Read PORTx
Write PORTx
TRISx
Read LATx
Data Bus
To peripherals
ANSELx
VDD
VSS