em78p468l ELAN Microelectronics Corp, em78p468l Datasheet - Page 40

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

EM78P468N/EM78P468L
8-Bit Microcontroller
34 •
6.8 Interrupt
This LSI has eight interrupt sources as listed below:
This IC has internal interrupts which are falling edge triggered or as follows :
If these interrupt sources change signal from high to low, the RF register will generate a
“1” flag to the corresponding register if the IOCF0 register is enabled.
RF is the interrupt status register. It records the interrupt request in flag bit. IOCF0 is
the interrupt mask register. Global interrupt is enabled by ENI instruction and disabled
by DISI instruction. When one of the interrupts (when enabled) is generated, it will
cause the next instruction to be fetch from address 0003H~0018H according to
interrupt source.
With this LSI, each individual interrupt source has its own interrupt vector as depicted in
Table 3. Before the interrupt subroutine is executed, the contents of the ACC and the
R3 register are initially saved by the hardware. After the interrupt service routine is
completed, the ACC and R3 are restored. The existing interrupt service routine does
not allow other interrupt service routine to be executed. Hence, if other interrupts occur
while an existing interrupt service routine is being executed, the hardware will save the
later interrupts. Only after the existing interrupt service routine is completed that the
next interrupt service routine is executed.
Interrupt Source
TCC overflow interrupt.
External interrupt P5.4/INT0 pin
External interrupt P5.5/INT1 pin
Counter 1 underflow interrupt
Counter 2 underflow interrupt
High-pulse width timer underflow interrupt
Low-pulse width timer underflow interrupt
Port 6, Port 8 input status change wake-up
TCC timer overflow interrupt
Four 8-bits down counter/timer underflow interrupt
ENI / DISI
Fig. 6-13 Interrupt Back-up Diagram
(This specification is subject to change without further notice)
ACC
R3
Product Specification (V1.5) 02.15.2007
Interrupt
Occurs
RETI
STACKACC
STACKR3