C541U_99 Datasheet, PDF (149/192 Pages) Siemens Semiconductor Group – 8-BIT CMOS MICROCONTROLLER

Interrupt System
C541U
7.1.3 Interrupt Prioritiy Registers
Each interrupt source can also be individually programmed to one of two priority levels by setting or
clearing a bit in the SFRs IP0 or IP1 (interrupt priority: 0 = low priority, 1 = high priority).
Special Function Registers IP0 (Address B8H)
Special Function Registers IP1 (Address B9H)
Reset Value : XXXX0000B
Reset Value : XXXXX000B
Bit No. MSB
LSB
7
6
5
4
3
2
1
0
B8H
–
–
–
–
PT1 PX1 PT0 PX0 IP0
B9H
–
–
–
–
–
PUDI PUEI PSSC IP1
Bit
–
PT1
PX1
PT0
PX0
PUDI
PUEI
PSSC
Function
Reserved for future use.
Timer 1 overflow interrupt priority level
If PT1 = 0, the timer 1 interrupt has a low priority.
If PT1 = 1, the timer 1 interrupt has a high priority
External interrupt 1 priority level
If PX1 = 0, the external interrupt 1 has a low priority.
If PX1 = 1, the external interrupt 1 has a high priority.
Timer 0 overflow interrupt priority level
If PT0 = 0, the timer 0 interrupt has a low priority.
If PT0 = 1, the timer 0 interrupt has a high priority.
External interrupt 0 priority level
If PX0 = 0, the external interrupt 0 has a low priority.
If PX0 = 1, the external interrupt 0 has a high priority.
USB device interrupt priority level
If PUDI = 0, the USB device interrupt has a low priority.
If PUDI = 1, the USB device interrupt has a high priority.
USB endpoint interrupt priority level
If PUEI = 0, the USB endpoint interrupt has a low priority.
If PUEI = 1, the USB endpoint interrupt has a high priority.
SSC interrupt priority level
If PSSC = 0, the SSC interrupt has a low priority.
If PSSC = 1, the SSC interrupt has a high priority.
Semiconductor Group
7-16
1997-10-01