em78p164n ELAN Microelectronics Corp, em78p164n Datasheet - Page 39

• Manufacturer Part Number: em78p164n
• Description: 8-bit Microcontroller With Otp Rom
• Manufacturer: ELAN Microelectronics Corp

Product Specification (V1.4) 05.28.2010
(This specification is subject to change without further notice)
The flag (except ICIF bit) in the Interrupt Status Register (RF) is set regardless of the
status of its mask bit or the execution of ENI. Note that the outcome of RF will be the
logic AND of RF and IOCF (refer to Figure 5-9). The RETI instruction ends the interrupt
routine and enables the global interrupt (execution of ENI).
When an interrupt is generated by the Timer clock / counter (if enabled), the next
instruction will be fetched from Address 009H, and 00FH (TCC, Timer 1 respectively).
Before an interrupt subroutine is executed, the contents of ACC and the R3 and R4
registers will be saved by the hardware. If another interrupt occurs, the ACC, R3, and R4
will be replaced by the new interrupt. After the interrupt service routine is completed, the
ACC, R3, and R4 registers are restored.
In EM78P164N, each individual interrupt source has its own interrupt vector as
depicted in the table below.
Interrupt sources
Interrupt Vector
ENI/DISI
00CH
00FH
003H
006H
009H
External interrupt
Port 6 pin change
TCC overflow interrupt
Comparator interrupt
Timer 1 (PWM) overflow interrupt
Figure 5-10 Interrupt Backup Diagram
Interrupt Status
ACC
R3
R4
8-Bit Microcontroller with OTP ROM
*Priority : 1 = highest ; 5 = lowest priority
Interrupt
occurs
RETI
Priority*
EM78P164N
STACKACC
STACKR3
STACKR4
1
2
3
5
4
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