SAB80515 Datasheet, PDF (124/270 Pages) Siemens Semiconductor Group – 8-Bit Single-Chip Microcontroller Family

Interrupt System
Table 8-2
Interrupt Sources and Vectors
Interrupt Request Flags
IE0
TF0
IE1
TF1
RI/TI
TF2/EXF2
IADC
IEX2
IEX3
IEX4
IEX5
IEX6
Interrupt Vector Address
0003H
000BH
0013H
001BH
0023H
002BH
0043H
004BH
0053H
005BH
0063H
006BH
Interrupt Source
External interrupt 0
Timer overflow
External interrupt 1
Timer 1 overflow
Serial channel
Timer 2 overflow/ext. reload
A/D converter
External interrupt 2
External interrupt 3
External interrupt 4
External interrupt 5
External interrupt 6
Execution proceeds from that location until the RETI instruction is encountered. The RETI
instruction informs the processor that the interrupt routine is no longer in progress, then pops the
two top bytes from the stack and reloads the program counter. Execution of the interrupted program
continues from the point where it was stopped. Note that the RETI instruction is very important
because it informs the processor that the program left the current interrupt priority level. A simple
RET instruction would also have returned execution to the interrupted program, but it would have
left the interrupt control system thinking an interrupt was still in progress. In this case no interrupt of
the same or lower priority level would be acknowledged.
Semiconductor Group
124