C505_9708 SIEMENS [Siemens Semiconductor Group], C505_9708 Datasheet - Page 176

• Manufacturer Part Number: C505_9708
• Description: 8-Bit CMOS Microcontroller
• Manufacturer: SIEMENS [Siemens Semiconductor Group]

7.1
7.1.1 Interrupt Enable Registers
Each interrupt vector can be individually enabled or disabled by setting or clearing the
corresponding bit in the interrupt enable registers IEN0 and IEN1. Register IEN0 also contains the
global disable bit (EA), which can be cleared to disable all interrupts at once. Generally, after reset
all interrupt enable bits are set to 0. That means that the corresponding interrupts are disabled.
The IEN0 register contains the general enable/disable flags of the external interrupts 0 and 1, the
timer interrupts, and the USART interrupt.
Special Function Register IEN0 (Address A8 H )
Bit
EA
ET2
ES
ET1
EX1
ET0
EX0
Semiconductor Group
Bit No.
Interrupt Registers
A8 H
Function
Enable/disable all interrupts.
If EA=0, no interrupt will be acknowledged.
If EA=1, each interrupt source is individually enabled or disabled by setting or
clearing its enable bit.
Timer 2 overflow / external reload interrupt enable.
If ET2 = 0, the timer 2 interrupt is disabled.
If ET2 = 1, the timer 2 interrupt is enabled.
Serial channel (USART) interrupt enable
If ES = 0, the serial channel interrupt 0 is disabled.
If ES = 1, the serial channel interrupt 0 is enabled.
Timer 1 overflow interrupt enable.
If ET1 = 0, the timer 1 interrupt is disabled.
If ET1 = 1, the timer 1 interrupt is enabled.
External interrupt 1 enable.
If EX1 = 0, the external interrupt 1 is disabled.
If EX1 = 1, the external interrupt 1 is enabled.
Timer 0 overflow interrupt enable.
If ET0 = 0, the timer 0 interrupt is disabled.
If ET0 = 1, the timer 0 interrupt is enabled.
External interrupt 0 enable.
If EX0 = 0, the external interrupt 0 is disabled.
If EX0 = 1, the external interrupt 0 is disabled.
MSB
EA
AF
H
The shaded bits are not used for interrupt control.
WDT
AE
H
ET2
AD
H
ES
AC
H
7-5
ET1
AB
H
EX1
AA
H
ET0
A9
H
LSB
EX0
A8
Interrupt System
H
Reset Value : 00 H
C505 / C505C
IEN0
1997-08-01