NT6868A

6

I/O Ports

The NT6868A has 31 pins dedicated to input and output. These pins are grouped into 6 ports, as follows:

PORT 0 (P00 - P07):

Port 0 is an 8-bit bi-directional CMOS I/O port that is internally pulled High by PMOS. Each pin of port 0 can be bit

programmed as an input or output pin under the software control. When programmed as output, data is latched to the port

data register and output to the pin. Port 0 pins with ''1'' written to them are pulled high by the internal PMOS pull-ups, and

are used as inputs in that state. These input signals can then be read. The port output is High after reset.

PORT 1 ( P10 - P17 ) : Functions the same as PORT 0.

PORT 2 ( P20 - P27) : Functions the same as PORT 0.

PORT 3 ( P30 - P34) : Functions the same as PORT 0.

CLK & DATA

: These two pins have the same structure as I/O ports, except for the 10K

Ω internal pull-ups.

PORT Registers:

Addr.

Bit

7

6

5

4

3

2

1

0

$00C3

PORT0

PD07

PD06

PD05

PD04

PD03

PD02

PD01

PD00

(RW)

$00C4

PORT1

PD17

PD16

PD15

PD14

PD13

PD12

PD11

PD10

(RW)

$00C5

PORT2

PD27

PD26

PD25

PD24

PD23

PD22

PD21

PD20

(RW)

$00C6

PORT3

-

-

-

PD34

PD33

PD32

PD31

PD30

(RW)

$00C7

CLK

-

-

-

-

-

-

-

CLK

(RW)

$00C8

DATA

-

-

-

-

-

-

-

DATA

(RW)

SD

D

L

Q

Latch

WREN

DB

RST

RDENB

IO

Weak PMOS

IO Port Structure