
PIC16C9XX
DS30444E - page 32
1997 Microchip Technology Inc.
TABLE 5-1: PORTA FUNCTIONS
TABLE 5-2: SUMMARY OF REGISTERS ASSOCIATED WITH PORTA
Name
Bit#
Buffer
Function
RA0/AN0(1)
bit0
TTL
Input/output or analog input
RA1/AN1(1)
bit1
TTL
Input/output or analog input
RA2/AN2(1)
bit2
TTL
Input/output or analog input
RA3/AN3/VREF(1) bit3
TTL
Input/output or analog input or VREF
RA4/T0CKI
bit4
ST
Input/output or external clock input for Timer0
Output is open drain type
RA5/AN4/SS (1)
bit5
TTL
Input/output or analog input or slave select input for synchronous serial port
Legend: TTL = TTL input, ST = Schmitt Trigger input
Note 1: The AN and VREF functions are for the A/D module and are only implemented on the PIC16C924.
Address
Name
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Value on
Power-on
Reset
Value on
all other
resets
05h
PORTA
—
RA5
RA4
RA3
RA2
RA1
RA0
(2)
85h
TRISA
—
PORTA Data Direction Control Register
--11 1111
9Fh(1)
ADCON1
—
PCFG2
PCFG1
PCFG0
---- -000
Legend: x = unknown, u = unchanged, - = unimplemented locations read as '0'. Shaded cells are not used by PORTA.
Note
1: The ADCON1 register is implemented on the PIC16C924 only.
2: PIC16C923 reset values for PORTA: --xx xxxx for a POR, and --uu uuuu for all other resets,
PIC16C924 reset values for PORTA: --0x 0000 when read.