PIC16F818/819
FIGURE 5-12:
BLOCK DIAGRAM OF RB4 PIN
Port/SSPEN
SCK/SCL
1
0
VDD
(2)
RBPU
Weak
Pull-up
P
VDD
SCL Drive
P
Data Latch
Data Bus
D
Q
WR
PORTB
(1)
I/O pin
N
CK
TRIS Latch
VSS
D
Q
WR
TRISB
CK
TTL
Input
Buffer
RD TRISB
Latch
Q
D
EN
Q1
RD PORTB
Set RBIF
Q
D
From other
RB7:RB4 pins
RD PORTB
Q3
EN
SCK
(3)
SCL
Note 1: I/O pins have diode protection to VDD and VSS.
2: To enable weak pull-ups, set the appropriate TRIS bit(s) and clear the RBPU bit.
2
3: The SCL Schmitt Trigger conforms to the I C™ specification.
2004 Microchip Technology Inc.
DS39598E-page 49