EM78468
8-BIT Microcontroller
4.4 I/O Ports
The I/O registers, (PORT 5, PORT 6, PORT 7and PORT 8), are bi-directional tri-state I/O
ports. PORT 6 and PORT 8 are pulled-high internally by software; PORT 6 is also
pulled-low internally by software. Furthermore, PORT 6 has its open-drain output also
through software. PORT 6 and PORT 8 features an input status changed interrupt (or
wake-up) function and is pulled-high by software. Each I/O pin can be defined as "input"
or "output" pin by the I/O control register (IOC50 ~ IOC80). The I/O registers and I/O
control registers are both readable and writable. The I/O interface circuits are shown in
Fig. 8
NOTE: Open-drain, pull high, and pull down are not shown in the figure.
Fig. 8 The Circuit of I/O Port and I/O Control Register for PORT 5 ~ 8
30 •
Product Specification (V1.1) 04.11.2005
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
