5-3

I/O PORTS

Figure 5-1. Ports 1, 2, 5, and 6 Internal Structure (87C196LA, LB Only)

5.2.1 Configuring Ports 1, 2, 5, and 6 (Bidirectional Ports)Using the port mode register, you can individually configure each pin for port 1, 2, 5, and 6 tooperate either as a general-purpose I/O signal (I/O mode) or as a special-function signal (special-function mode). In either mode, three configurations are possible: complementary output, high-
Q2
Q1
P
x
_MODE
P
x
_DRV
SFDIR
0
1
P
x
_REG
Sample
Latch
PH1 Clock
Internal Bus
SFDATA
Any Write to P
x
_MODE
Q
RWeak
Pullup
RESET# Q3
Q4
Buffer
Read Port
S
300ns Delay
I/O Pin
RESET#
A5265-01
150 to 200R1
0
1
VSS
Medium
Pullup
VSS
VSS
VCC
RESET#
P
x
_PIN
DQ
LE