I/O PORTS

Internal Bus

 

 

 

VCC

 

 

 

 

 

 

Px_REG

0

 

 

 

 

 

 

 

 

 

SFDATA

1

 

 

Q1

 

 

 

 

 

 

I/O Pin

Px_DRV

0

 

 

 

 

 

 

 

Q2

 

SFDIR

 

 

 

 

1

 

 

 

 

 

 

 

RESET#

VSS

 

Px_MODE

 

 

 

 

 

 

 

 

 

 

Sample

 

150Ω to 200Ω

R1

 

Latch

 

 

 

 

 

Px_PIN

Buffer

 

 

 

Q

D

 

 

 

 

LE

 

 

 

 

Read Port

 

 

 

 

 

 

PH1 Clock

 

 

 

 

 

 

 

Medium

 

 

300ns Delay

 

Pullup

 

 

 

Q3

 

RESET#

 

 

 

 

 

 

 

 

 

 

 

 

 

VSS

 

 

 

 

 

Weak

 

 

RESET#

R

Pullup

 

 

 

 

Q

Q4

 

 

Any Write to Px_MODE

S

 

 

 

 

 

 

VSS

 

 

 

 

 

 

A5265-01

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

 

5.2.1Configuring 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 to operate 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-

5-3

Page 47
Image 47
Intel 87C196CA, 8XC196Jx, 8XC196Lx, 8XC196Kx user manual Configuring Ports 1, 2, 5, and 6 Bidirectional Ports