FUJITSU MB91F109 FR30 User Manual

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CHAPTER 3 CLOCK GENERATOR AND CONTROLLER

[Example]

Since the register consists of four bits, the DMA suppression function cannot be used for more
than 15 concurrent interrupts. Always give a DMA task a priority that is at least 15 levels higher
than that of other interrupts.

INT-ENTRY

LDI:20

#PDRR, R10

@R10, R1

; GET PDRR VALUE INTO R1

ADD

#1, R1

R1, @R10

; PDRR:=PDRR+1, DMA disabled

LDI:20

#int-REG, R10

; int occurred with int-REG

LDI:8

#10H, R1

; example, int-flag=#10h

R1, @R10

; CLEAR int-REQ, (but still DMA disabled)

;

interrupt execute routine

LDI:20

#PDRR, R10

@R10, R1

; GET PDRR VALUE INTO R1

ADD2

#-1, R1

R1, @R10

; PDRR:=PDRR-1, DMA may be enabled

RETI