em78p5842 ELAN Microelectronics Corp, em78p5842 Datasheet - Page 26

• Manufacturer Part Number: em78p5842
• Description: 8-bit Micro-controller
• Manufacturer: ELAN Microelectronics Corp

__________________________________________________________________________________________________________________________________________________________________
* This specification is subject to change without notice.
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.9.
PORT
Fig.9_2 The input/output circuit of EM785840 input/output ports
Fig.9_1 The circuit of I/O port and I/O control register
0
1
M
U
X
Q
Q
Q
Q
24
PCRD
R
P
C
R
L
P
C
L
CLK
CLK
D
D
VDD
pull
high
PCWR
PDWR
PDRD
VDD
120
ohm
EM785840/5841/5842
VDD
8-bit Micro-controller
2004/11/10 V1.2
PIN
IOD