
PIC18C601/801
DS39541A-page 104
Advance Information
2001 Microchip Technology Inc.
FIGURE 9-2:
RA4/T0CKI PIN BLOCK
DIAGRAM
TABLE 9-1:
PORTA FUNCTIONS
TABLE 9-2:
SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
Data
Bus
WR TRISA
RD PORTA
Data Latch
TRIS Latch
RD TRISA
Schmitt
Trigger
Input
Buffer
N
VSS
I/O pin(1)
TMR0 Clock Input
Note 1: I/O pin has diode protection to VSS only.
Q
D
Q
CK
Q
D
Q
CK
EN
QD
EN
RD LATA
WR LATA
or
WR PORTA
Name
Bit#
Buffer
Function
RA0/AN0
bit0
TTL
Input/output or analog input
RA1/AN1
bit1
TTL
Input/output or analog input
RA2/AN2/VREF-
bit2
TTL
Input/output or analog input or VREF-
RA3/AN3/VREF+
bit3
TTL
Input/output or analog input or VREF+
RA4/T0CKI
bit4
ST/OD
Input/output or external clock input for Timer0, output is open drain type
RA5/SS/AN4/LVDIN
bit5
TTL
Input/output or slave select input for synchronous serial port or analog
input or low voltage detect input
Legend: TTL = TTL input, ST = Schmitt Trigger input, OD = Open Drain
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
POR,
BOR
Value on all
other
RESETS
PORTA
—
RA5
RA4
RA3
RA2
RA1
RA0
--0x 0000
--uu uuuu
LATA
—
Latch A Data Output Register
-xxx xxxx
-uuu uuuu
TRISA
—
PORTA Data Direction Register
-111 1111
ADCON1
—
VCFG1 VCFG0
PCFG3
PCFG2
PCFG1
PCFG0 --00 0000 --uu uuuu
Legend: x = unknown, u = unchanged, - = unimplemented locations read as '0'.
Shaded cells are not used by PORTA.