EM785830AA

8-bit Micro-controller

__________________________________________________________________________________________________________________________________________________________________

* This specification is subject to be changed without notice.

27

12/1/2004

V1.6

VII.4 I/O Port

The I/O registers are bi-directional tri-state I/O ports. The I/O ports can be defined as "input" or "output" pins by

the I/O control registers under program control. The I/O data registers and I/O control registers are both readable

and writable. The I/O interface circuit is shown in Fig.11.

Fig.11_1 The circuit of I/O port and I/O control register

PIN

120

ohm

VDD

VDD

VDD

pull

high

Fig.11_2 The input/output circuit of EM785830AA input/output ports

M

U

X

0

1

PDRD

PDWR

CLK

C

L

P

R

D

Q

Q

CLK

C

L

P

R

D

Q

Q

PCWR

IOD

PCRD

PORT