PIC16F87XA
TABLE 4-3:
PORTB FUNCTIONS
Name
Bit#
Buffer
Function
RB0/INT
bit0
TTL/ST(1)
Input/output pin or external interrupt input.
Internal software programmable weak pull-up.
RB1
bit1
bit2
bit3
TTL
TTL
TTL
Input/output pin. Internal software programmable weak pull-up.
Input/output pin. Internal software programmable weak pull-up.
RB2
RB3/PGM(3)
Input/output pin or programming pin in LVP mode. Internal software
programmable weak pull-up.
RB4
bit4
bit5
bit6
bit7
TTL
Input/output pin (with interrupt-on-change). Internal software programmable
weak pull-up.
RB5
TTL
Input/output pin (with interrupt-on-change). Internal software programmable
weak pull-up.
RB6/PGC
RB7/PGD
TTL/ST(2)
TTL/ST(2)
Input/output pin (with interrupt-on-change) or In-Circuit Debugger pin.
Internal software programmable weak pull-up. Serial programming clock.
Input/output pin (with interrupt-on-change) or In-Circuit Debugger pin.
Internal software programmable weak pull-up. Serial programming data.
Legend: TTL = TTL input, ST = Schmitt Trigger input
Note 1: This buffer is a Schmitt Trigger input when configured as the external interrupt.
2: This buffer is a Schmitt Trigger input when used in Serial Programming mode or In-Circuit Debugger.
3: Low Voltage ICSP Programming (LVP) is enabled by default, which disables the RB3 I/O function. LVP
must be disabled to enable RB3 as an I/O pin and allow maximum compatibility to the other 28-pin and
40-pin mid-range devices.
TABLE 4-4:
Address
SUMMARY OF REGISTERS ASSOCIATED WITH PORTB
Value on: Value on
Name
Bit 7
Bit 6
Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0
POR,
BOR
all other
RESETS
xxxx xxxx uuuu uuuu
1111 1111 1111 1111
1111 1111 1111 1111
06h, 106h PORTB
86h, 186h TRISB
RB7
RB6
RB5
RB4 RB3 RB2 RB1 RB0
PORTB Data Direction Register
81h, 181h OPTION_REG RBPU INTEDG T0CS T0SE PSA PS2 PS1 PS0
Legend: x= unknown, u= unchanged. Shaded cells are not used by PORTB.
2001 Microchip Technology Inc.
Advance Information
DS39582A-page 43
MICROCHIP [ MICROCHIP ]
