
2001 Microchip Technology Inc.
Advance Information
DS39541A-page 111
PIC18C601/801
FIGURE 9-8:
PORTD BLOCK DIAGRAM IN SYSTEM BUS MODE
Instruction Register
Bus Enable
Data/TRIS Out
Drive Bus
System Bus
Control
Data Bus
WR LATD
WR TRISD
RD PORTD
Data Latch
TRIS Latch
RD TRISD
TTL
Input
Buffer
I/O pin(1)
Q
D
CK
Q
D
CK
EN
QD
EN
RD LATD
or
PORTD
0
1
Port
Data
Instruction Read
Note 1: I/O pins have protection diodes to VDD and VSS.