
PIC16F87X
DS30292C-page 30
2001 Microchip Technology Inc.
TABLE 3-1:
PORTA FUNCTIONS
TABLE 3-2:
SUMMARY OF REGISTERS ASSOCIATED WITH 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
bit2
TTL
Input/output or analog input.
RA3/AN3/VREF
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/SS/AN4
bit5
TTL
Input/output or slave select input for synchronous serial port or analog input.
Legend: TTL = TTL input, ST = Schmitt Trigger input
Address
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
05h
PORTA
—
RA5
RA4
RA3
RA2
RA1
RA0
--0x 0000
--0u 0000
85h
TRISA
—
PORTA Data Direction Register
--11 1111
9Fh
ADCON1 ADFM
—
PCFG3 PCFG2 PCFG1 PCFG0 --0- 0000
--0- 0000
Legend: x = unknown, u = unchanged, - = unimplemented locations read as '0'.
Shaded cells are not used by PORTA.
Note:
When using the SSP module in SPI Slave mode and SS enabled, the A/D converter must be set to one of
the following modes, where PCFG3:PCFG0 = 0100,0101, 011x, 1101, 1110, 1111.