em78p468l ELAN Microelectronics Corp, em78p468l Datasheet - Page 31

• Manufacturer Part Number: em78p468l
• Description: 8-bit Microcontroller
• Manufacturer: ELAN Microelectronics Corp

Product Specification (V1.5) 02.15.2007
(This specification is subject to change without further notice)
6.4 I/O Ports
6.5 Reset and Wake-up
The I/O registers, (Port 5, Port 6, Port 7 and 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. 6-5.
A reset can be activated by
Note: The reset circuit is always enabled. It will reset the CPU at 1.9V.
Note: Open-drain, pull-high, and pull down are not shown in the figure.
POR (Power-on Reset)
WDT timeout. (if enabled)
/RESET pin goes to low.
The oscillator is running, or will be started.
The program counter (R2/PC) is set to all "0".
All I/O port pins are configured as input mode (high-impedance state).
The TCC/Watchdog timer and prescaler are cleared.
When power is on, the Bits 5 and 6 of R3 and the upper two bits of R4 are cleared.
Bits of the IOC71 register are set to all "1" except for Bit 6 (INT flag).
For other registers, see Table 2.
Once a reset occurs, the following functions are performed
Fig. 6-5 The Circuit of I/O Port and I/O Control Register for Port 5 ~ 8
EM78P468N/EM78P468L
8-Bit Microcontroller
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