SN8P2200 Series
USB 1.1 Low-Speed 8-Bit Micro-Controller
SONiX TECHNOLOGY CO., LTD
Page 69
Version 1.7
6.12
MULTI-INTERRUPT OPERATION
Under certain condition, the software designer uses more than one interrupt requests. Processing multi-interrupt
request requires setting the priority of the interrupt requests. The IRQ flags of interrupts are controlled by the interrupt
event. Nevertheless, the IRQ flag “1” doesn’t mean the system will execute the interrupt vector. In addition, which
means the IRQ flags can be set “1” by the events without enable the interrupt. Once the event occurs, the IRQ will be
logic “1”. The IRQ and its trigger event relationship is as the below table.
Interrupt Name
Trigger Event Description
P00IRQ
P0.0 trigger controlled by PEDGE
T0IRQ T0C
overflow
TC0IRQ TC0C
overflow
USBIRQ
USB process finished
T1IRQ T1C
stop
counting.
T2IRQ T2C
stop
counting.
For multi-interrupt conditions, two things need to be taking care of. One is to set the priority for these interrupt requests.
Two is using IEN and IRQ flags to decide which interrupt to be executed. Users have to check interrupt control bit and
interrupt request flag in interrupt routine.
¾
Example: Check the interrupt request under multi-interrupt operation
ORG
8
; Interrupt vector
JMP
INT_SERVICE
INT_SERVICE:
…
; Push routine to save ACC and PFLAG to buffers.
INTP00CHK:
;
Check
INT0 interrupt request
B0BTS1
FP00IEN
; Check P00IEN
JMP
INTT0CHK
; Jump check to next interrupt
B0BTS0
FP00IRQ
; Check P00IRQ
JMP
INTP00
INTT0CHK:
; Check T0 interrupt request
B0BTS1
FT0IEN
; Check T0IEN
JMP
INTTC0CHK
; Jump check to next interrupt
B0BTS0
FT0IRQ
; Check T0IRQ
JMP
INTT0
; Jump to T0 interrupt service routine
INTTC0CHK:
; Check TC0 interrupt request
B0BTS1
FTC0IEN
; Check TC0IEN
JMP
INTTC1CHK
; Jump check to next interrupt
B0BTS0
FTC0IRQ
; Check TC0IRQ
JMP
INTTC0
; Jump to TC0 interrupt service routine
INTUSBCHK:
; Check USB interrupt request
B0BTS1
FUSBIEN
; Check USBIEN
JMP
INTT1CHK
; Jump check to next interrupt
B0BTS0
FUSBIRQ
; Check USBIRQ
JMP
INTUSB
; Jump to USB interrupt service routine
INTT1CHK:
; Check T1 interrupt request
B0BTS1
FT1IEN
; Check T1IEN
JMP
INTT2CHK
; Jump check to next interrupt
B0BTS0
FT1IRQ
; Check T1IRQ
JMP
INTT1
; Jump to T1 interrupt service routine
INTT2CHK:
; Check T2 interrupt request
B0BTS1
FADCIEN
; Check T2IEN
JMP
INT_EXIT
; Jump to exit of IRQ
B0BTS0
FT2IRQ
; Check T2IRQ
JMP
INTT2
; Jump to T2 interrupt service routine
INT_EXIT:
…
; Pop routine to load ACC and PFLAG from buffers.
RETI
; Exit interrupt vector
