
Preliminary W78E365
Publication Release Date: April 2001
- 7 -
Revision A1
XICON - external interrupt control (C0H)
PX3
EX3
IE3
IT3
PX2
EX2
IE2
IT2
PX3:
EX3:
IE3:
IT3:
PX2:
EX2:
IE2:
IT2:
Eight-source interrupt informations:
INTERRUPT SOURCE
External interrupt 3 priority high if set
External interrupt 3 enable if set
If IT3 = 1, IE3 is set/cleared automatically by hardware when interrupt is detected/serviced
External interrupt 3 is falling-edge/low-level triggered when this bit is set/cleared by software
External interrupt 2 priority high if set
External interrupt 2 enable if set
If IT2 = 1, IE2 is set/cleared automatically by hardware when interrupt is detected/serviced
External interrupt 2 is falling-edge/low-level triggered when this bit is set/cleared by software
VECTOR
ADDRESS
POLLING
SEQUENCE WITHIN
PRIORITY LEVEL
0 (highest)
1
2
3
4
5
6
7 (lowest)
ENABLE
REQUIRED
SETTINGS
IE.0
IE.1
IE.2
IE.3
IE.4
IE.5
XICON.2
XICON.6
INTERRUPT
TYPE
EDGE/LEVEL
TCON.0
-
TCON.2
-
-
-
XICON.0
XICON.3
External Interrupt 0
Timer/Counter 0
External Interrupt 1
Timer/Counter 1
Serial Port
Timer/Counter 2
External Interrupt 2
External Interrupt 3
03H
0BH
13H
1BH
23H
2BH
33H
3BH
Clock
The W78E365 is designed to be used with either a crystal oscillator or an external clock. Internally, the
clock is divided by two before it is used by default. This makes the W78E365 relatively insensitive to
duty cycle variations in the clock.
Crystal Oscillator
The W78E365 incorporates a built-in crystal oscillator. To make the oscillator work, a crystal must be
connected across pins XTAL1 and XTAL2. In addition, a load capacitor must be connected from each
pin to ground, and a resistor must also be connected from XTAL1 to XTAL2 to provide a DC bias when
the crystal frequency is above 24 MHz.
External Clock
An external clock should be connected to pin XTAL1. Pin XTAL2 should be left unconnected. The
XTAL1 input is a CMOS-type input, as required by the crystal oscillator. As a result, the external clock
signal should have an input one level of greater than 3.5 volts.