EM78P5840N/41N/42N
8-Bit Microcontrollers
7.6 I/O Port
7.6.1
I/O Structure
The I/O registers are bidirectional 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 ports and
control registers circuits are illustrated below.
PCRD
P
R
Q
Q
D
CLK
PCWR
C
L
P
R
PORT
Q
Q
D
IOD
CLK
PDWR
PDRD
C
L
0
1
M
U
X
Figure 7-7a I/O Port and I/O Control Register Circuit
VDD
VDD
VDD
pull
high
PIN
120
ohm
Figure 7-7b EM785840N/41N/42N Input/output Ports Circuit
Product Specification (V1.0) 04.25.2006
(This specification is subject to change without further notice)
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ELAN [ ELAN MICROELECTRONICS CORP ]
