4513_03 Datasheet, PDF (124/210 Pages) Renesas Technology Corp – 4-BIT SINGLE-CHIP MICROCOMPUTER

APPLICATION
2.2 Interrupts
ΠDisable Interrupts
Timer 1 interrupt is temporarily disabled.
Interrupt enable flag INTE “0”
All interrupts disabled (DI instruction)
Interrupt control register V1
b3
!
0
b0
!!
Timer 1 interrupt occurrence disabled
(TV1A instruction)
 Stop Timer Operation
Timer 1 and prescaler are temporarily stopped.
Dividing ratio of prescaler is selected.
b3
b0 _{Timer 1 stop (TW1A instruction)}
Timer control register W1 0 1 0 ! _{Prescaler stop}
Prescaler divided by 16 selected
Ž Set Timer Value
Timer 1 count time is set. (The formula is shown gA below.)
Timer 1 reload register R1 “5216” Timer count value 82 set (T1AB instruction)
 Clear Interrupt Request
Timer 1 interrupt activated condition is cleared.
Timer 1 interrupt request flag T1F “0” ^{g0 h} Timer 1 interrupt activated condition cleared
(SNZT1 instruction)
Note when the interrupt request is cleared
When  is executed, considering the skip of the next instruction according to the
interrupt request flag T1F, insert the NOP instruction after the SNZT1 instruction.
 Start Timer Operation
Timer 1 and prescaler temporarily stopped are restarted.
b3
b0
Timer control register W1 1 1 1 !
Timer 1 operation start (TW1A instruction)
Prescaler operation stop
‘ Enable Interrupts
The Timer 1 interrupt which is temporarily disabled is enabled.
Interrupt control register V1
b3
b0
!¹ !!
Timer 1 interrupt occurrence enabled
(TV1A instruction)
Interrupt enable flag INTE “1”
All interrupts enabled (EI instruction)
Constant period interrupt execution start
gA The prescaler dividing ratio and timer 1 count value to make the interrupt occur every 1 ms are set as follows.
1 ms ≅ (4.0 MHz)^–1 ! 3
! 16 ! (82+1)
System clock Instruction Prescaler Timer 1
clock
dividing count
ratio
value
“!”: it can be “0” or “1.”
Fig. 2.2.5 Timer 1 constant period interrupt setting example
4513/4514 Group User’s Manual
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