C501_1 Datasheet, PDF (84/121 Pages) Siemens Semiconductor Group – 8-Bit Single-Chip Microcontroller

Interrupt System
C501
7.1.3 Interrupt Priority Register
Each interrupt source can also be individually programmed to one of two priority levels by setting or
clearing a bit in the SFR IP (Interrupt Priority, 0: low priority, 1: high priority).
Special Function Register IP (Address B8H)
Reset Value : XX000000B
MSB
LSB
Bit No. 7
6
5
4
3
2
1
0
B8H
–
– PT2 PS PT1 PX1 PT0 PX0 IP
The shaded bits are not used for interrupt control.
Bit
Function
–
Not implemented. Reserved for future use.
PT2
Timer 2 Interrupt Priority Level.
If PT2 = 0, the Timer 2 interrupt has a low priority.
PS
Serial Channel Interrupt Priority Level.
If PS = 0, the Serial Channel interrupt has a low priority.
PT1
Timer 1 Overflow Interrupt Priority Level.
If PT1 = 0, the Timer 1 interrupt has a low priority.
PX1
External Interrupt 1 Priority Level.
If PX1 = 0, the external interrupt 1 has a low priority.
PT0
Timer 0 Overflow Interrupt Priority Level.
If PT0 = 0, the Timer 0 interrupt has a low priority.
PX0
External Interrupt 0 Priority Level.
If PX0 = 0, the external interrupt 0 has a low priority.
Semiconductor Group
7-6