SN8F2250B Series
USB 2.0 Full-Speed 8-Bit Micro-Controller
6.4 GIE GLOBAL INTERRUPT OPERATION
GIE is the global interrupt control bit. All interrupts start work after the GIE = 1 It is necessary for interrupt service
request. One of the interrupt requests occurs, and the program counter (PC) points to the interrupt vector (ORG 8) and
the stack add 1 level.
0DFH
STKP
Read/Write
After reset
Bit 7
GIE
R/W
0
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
STKPB2
R/W
Bit 1
STKPB1
R/W
Bit 0
STKPB0
R/W
-
-
-
-
-
-
-
-
-
-
-
-
1
1
1
Bit 7
GIE: Global interrupt control bit.
0 = Disable global interrupt.
1 = Enable global interrupt.
Example: Set global interrupt control bit (GIE).
B0BSET FGIE
; Enable GIE
Note: The GIE bit must enable during all interrupt operation.
6.5 PUSH, POP ROUTINE
When any interrupt occurs, system will jump to ORG 8 and execute interrupt service routine. It is necessary to save
ACC, PFLAG data. The chip includes “PUSH”, “POP” for in/out interrupt service routine. The two instructions save and
load ACC, PFLAG data into buffers and avoid main routine error after interrupt service routine finishing.
Note: ”PUSH”, “POP” instructions save and load ACC/PFLAG without (NT0, NPD). PUSH/POP buffer is
an unique buffer and only one level.
¾
Example: Store ACC and PAFLG data by PUSH, POP instructions when interrupt service routine
executed.
ORG
JMP
0
START
ORG
JMP
8
INT_SERVICE
ORG
…
10H
START:
INT_SERVICE:
PUSH
…
; Save ACC and PFLAG to buffers.
…
POP
; Load ACC and PFLAG from buffers.
RETI
…
; Exit interrupt service vector
ENDP
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