Datasheet
PIC16C7X
DS30390E-page 46 1997 Microchip Technology Inc.
FIGURE 5-4: BLOCK DIAGRAM OF
RB7:RB4 PINS (PIC16C73/74)
Data Latch
From other
RBPU
(2)
P
V
DD
I/O
QD
CK
QD
CK
QD
EN
QD
EN
Data bus
WR Port
WR TRIS
Set RBIF
TRIS Latch
RD TRIS
RD Port
RB7:RB4 pins
weak
pull-up
RD Port
Latch
TTL
Input
Buffer
pin
(1)
Note 1: I/O pins have diode protection to VDD and VSS.
ST
Buffer
RB7:RB6 in serial programming mode
2: To enable weak pull-ups, set the appropriate TRIS bit(s)
and clear the RBPU
bit (OPTION<7>).
FIGURE 5-5: BLOCK DIAGRAM OF
RB7:RB4 PINS (PIC16C72/
73A/74A/76/77)
Data Latch
From other
RBPU
(2)
P
V
DD
I/O
QD
CK
QD
CK
QD
EN
QD
EN
Data bus
WR Port
WR TRIS
Set RBIF
TRIS Latch
RD TRIS
RD Port
RB7:RB4 pins
weak
pull-up
RD Port
Latch
TTL
Input
Buffer
pin
(1)
Note 1: I/O pins have diode protection to VDD and VSS.
ST
Buffer
RB7:RB6 in serial programming mode
Q3
Q1
2: To enable weak pull-ups, set the appropriate TRIS bit(s)
and clear the RBPU
bit (OPTION<7>).
TABLE 5-3: 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 TTL Input/output pin. Internal software programmable weak pull-up.
RB2 bit2 TTL Input/output pin. Internal software programmable weak pull-up.
RB3 bit3 TTL Input/output pin. Internal software programmable weak pull-up.
RB4 bit4 TTL Input/output pin (with interrupt on change). Internal software programmable
weak pull-up.
RB5 bit5 TTL Input/output pin (with interrupt on change). Internal software programmable
weak pull-up.
RB6 bit6 TTL/ST
(2)
Input/output pin (with interrupt on change). Internal software programmable
weak pull-up. Serial programming clock.
RB7 bit7 TTL/ST
(2)
Input/output pin (with interrupt on change). 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.