Datasheet

ADuC841/ADuC842/ADuC843
Rev. 0 | Page 71 of 88
IEIP2 Secondary Interrupt Enable Register
SFR Address A9H
Power-On Default A0H
Bit Addressable No
Table 37. IEIP2 SFR Bit Designations
Bit No. Name Description
7 ---- Reserved.
6 PTI Priority for time interval interrupt.
5 PPSM Priority for power supply monitor interrupt.
4 PSI Priority for SPI/I
2
C interrupt.
3 ---- This bit must contain zero.
2 ETI Set by the user to enable, or cleared to disable time interval counter interrupts.
1 EPSMI Set by the user to enable, or cleared to disable power supply monitor interrupts.
0 ESI Set by the user to enable, or cleared to disable SPI or I
2
C serial port interrupts.
Interrupt Priority
The interrupt enable registers are written by the user to enable
individual interrupt sources, while the interrupt priority regis-
ters allow the user to select one of two priority levels for each
interrupt. An interrupt of a high priority may interrupt the
service routine of a low priority interrupt, and if two interrupts
of different priority occur at the same time, the higher level
interrupt is serviced first. An interrupt cannot be interrupted by
another interrupt of the same priority level. If two interrupts of
the same priority level occur simultaneously, a polling sequence
is observed as shown in Table 38.
Table 38. Priority within an Interrupt Level
Source Priority Description
PSMI 1 (Highest) Power Supply Monitor Interrupt.
WDS 2 Watchdog Timer Interrupt.
IE0 2 External Interrupt 0.
ADCI 3 ADC Interrupt.
TF0 4 Timer/Counter 0 Interrupt.
IE1 5 External Interrupt 1.
TF1 6 Timer/Counter 1 Interrupt.
ISPI/I2CI 7 SPI Interrupt/I
2
C Interrupt.
RI + TI 8 Serial Interrupt.
TF2 + EXF2 9 Timer/Counter 2 Interrupt.
TII 11(Lowest) Time Interval Counter Interrupt.
Interrupt Vectors
When an interrupt occurs, the program counter is pushed onto
the stack, and the corresponding interrupt vector address is
loaded into the program counter. The interrupt vector addresses
are shown in Table 39.
Table 39. Interrupt Vector Addresses
Source Vector Address
IE0 0003H
TF0 000BH
IE1 0013H
TF1 001BH
RI + TI 0023H
TF2 + EXF2 002BH
ADCI 0033H
ISPI/I2CI 003BH
PSMI 0043H
TII 0053H
WDS 005BH