PIC16F193X Datasheet, PDF (87/418 Pages) Microchip Technology – 28/40/44-Pin Flash-Based, 8-Bit CMOS Microcontrollers with LCD Driver and nanoWatt Technology

PIC16F193X/LF193X
6.2 PORTA Registers
PORTA is a 8-bit wide, bidirectional port. The
corresponding data direction register is TRISA
(Register 6-4). Setting a TRISA bit (= 1) will make the
corresponding PORTA pin an input (i.e., disable the
output driver). Clearing a TRISA bit (= 0) will make the
corresponding PORTA pin an output (i.e., enables
output driver and puts the contents of the output latch
on the selected pin). Example 6-1 shows how to
initialize PORTA.
Reading the PORTA register (Register 6-2) 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 (LATA).
The TRISA register (Register 6-4) controls the PORTA
pin output drivers, even when they are being used as
analog inputs. The user should ensure the bits in the
TRISA register are maintained set when using them as
analog inputs. I/O pins configured as analog input
always read ‘0’.
Note:
The ANSELA register must be initialized to
configure an analog channel as a digital
input. Pins configured as analog inputs will
read ‘0’.
EXAMPLE 6-1:
BANKSEL PORTA
CLRF PORTA
BANKSEL LATA
CLRF LATA
BANKSEL ANSELA
CLRF ANSELA
BANKSEL TRISA
MOVLW 0Ch
MOVWF TRISA
INITIALIZING PORTA
;
;Init PORTA
;Data Latch
;
;
;digital I/O
;
;Set RA<3:2> as inputs
;and set RA<7:4,1:0>
;as outputs
REGISTER 6-2: PORTA: PORTA REGISTER
R/W-x/u
RA7
bit 7
R/W-x/u
RA6
R/W-x/u
RA5
R/W-x/u
RA4
R/W-x/u
RA3
R/W-x/u
RA2
R/W-x/u
RA1
R/W-x/u
RA0
bit 0
Legend:
R = Readable bit
u = bit is unchanged
‘1’ = Bit is set
W = Writable bit
x = Bit is unknown
‘0’ = Bit is cleared
U = Unimplemented bit, read as ‘0’
-n/n = Value at POR and BOR/Value at all other Resets
bit 7-0
RA<7:0>: PORTA I/O Value bits⁽¹⁾
Note 1: Writes to PORTA are actually written to corresponding LATA register. Reads from PORTA register is return
of actual I/O pin values.
REGISTER 6-3: LATA: PORTA DATA LATCH REGISTER
R/W-x/u
LATA7
bit 7
R/W-x/u
LATA6
R/W-x/u
LATA5
R/W-x/u
LATA4
R/W-x/u
LATA3
R/W-x/u
LATA2
R/W-x/u
LATA1
R/W-x/u
LATA0
bit 0
Legend:
R = Readable bit
u = bit is unchanged
‘1’ = Bit is set
W = Writable bit
x = Bit is unknown
‘0’ = Bit is cleared
U = Unimplemented bit, read as ‘0’
-n/n = Value at POR and BOR/Value at all other Resets
bit 7-0
LATA<7:0>: PORTA Output Latch Value bits⁽¹⁾
Note 1: Writes to PORTA are actually written to corresponding LATA register. Reads from PORTA register is return
of actual I/O pin values.
© 2008 Microchip Technology Inc.
Preliminary
DS41364A-page 85