SN8F2250B Series
USB 2.0 Full-Speed 8-Bit Micro-Controller
6.8 T1 INTERRUPT OPERATION
When the T1C counter overflows, the T1IRQ will be set to “1” no matter the T1IEN is enable or disable. If the T1IEN
and the trigger event T1IRQ is set to be “1”. As the result, the system will execute the interrupt vector. If the T1IEN =
0, the trigger event T1IRQ is still set to be “1”. Moreover, the system won’t execute interrupt vector even when the
T1IEN is set to be “1”. Users need to be cautious with the operation under multi-interrupt situation.
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Example: T1 interrupt request setup.
B0BCLR
B0BCLR
MOV
B0MOV
MOV
B0MOV
MOV
B0MOV
FT1IEN
; Disable T1 interrupt service
; Disable T1 timer
;
; Set T1 clock = Fcpu / 256
; Set T1C_L initial value = E5H
FT1ENB
A, #00H
T1M, A
A, #0E5H
T1C_L, A
A, #48H
T1C_H, A
; Set T1C_H initial value = 48H
; Set T1 interval = 1s
B0BSET
B0BCLR
B0BSET
FT1IEN
FT1IRQ
FT1ENB
; Enable T1 interrupt service
; Clear T1 interrupt request flag
; Enable T1 timer
B0BSET
FGIE
; Enable GIE
Example: T1 interrupt service routine.
ORG
JMP
8
; Interrupt vector
INT_SERVICE
INT_SERVICE:
…
; Push routine to save ACC and PFLAG to buffers.
B0BTS1
JMP
FT1IRQ
EXIT_INT
; Check T1IRQ
; T1IRQ = 0, exit interrupt vector
B0BCLR
MOV
B0MOV
MOV
FT1IRQ
; Reset T1IRQ
; Reset T1C_L.
A, #0E5H
T1C_L, A
A, #48H
B0MOV
…
T1C_H, A
; Reset T1C_H.
; T1 interrupt service routine
…
EXIT_INT:
…
; Pop routine to load ACC and PFLAG from buffers.
; Exit interrupt vector
RETI
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