C517A_99 Datasheet, PDF (184/218 Pages) Siemens Semiconductor Group – 8-Bit CMOS Microcontroller

Interrupt System
C517A
7.1.3 Interrupt Priority Registers
The 17 interrupt sources of the C517A are combined to six interrupt groups. Each of the six interrupt
groups can be programmed to one of four priority levels by setting or clearing a bit in the IP0 and IP1
priority registers. Further deails abaout the interrupt priority structure are given in chapter 7.2.
Special Function Register IP0 (Address A9H)
Special Function Register IP1 (Address B9H)
Reset Value : 00H
Reset Value : XX000000B
MSB
LSB
Bit No. 7
6
5
4
3
2
1
0
A9H OWDS WDTS IP0.5 IP0.4 IP0.3 IP0.2 IP0.1 IP0.0 IP0
7
B9H
–
6
5
4
3
2
1
0
– IP1.5 IP1.4 IP1.3 IP1.2 IP1.1 IP1.0 IP1
Bit
IP1.x
IP0.x
The shaded bits are not used for interrupt purposes.
Function
Interrupt Priority level bits (x=0-5)
IP1.x IP0.x Function
0
0
Interrupt group x is set to priority level 0 (lowest)
0
1
Interrupt group x is set to priority level 1
1
0
Interrupt group x is set to priority level 2
1
1
Interrupt group x is set to priority level 3 (highest)
Semiconductor Group
7-14