Figure 9.7 Clear Interrupt Request Flag When Interrupt Factor Generation Signal - Renesas H8/3847R Series Hardware Manual

Method 1 is recommended to operate for time efficiency.
Method 1
1. Prohibit interrupt in interrupt handling routine (set IENFH, IENFL to 0).
2. After program process returned normal handling, clear interrupt request flags (IRRTFH,
IRRTFL) after more than that calculated with (1) formula.
3. After read timer control status register F (TCSRF), clear timer overflow flags (OVFH,
OVFL) and compare match flags (CMFH, CMFL).
4. Operate interrupt permission (set IENFH, IENFL to 1).
Method 2
1. Set interrupt handling routine time to more than time that calculated with (1) formula.
2. Clear interrupt request flags (IRRTFH, IRRTFL) at the end of interrupt handling routine.
3. After read timer control status register F (TCSRF), clear timer overflow flags (OVFH,
OVFL) and compare match flags (CMFH, CMFL).
All above attentions are also applied in 16-bit mode and 8-bit mode.
Program process
φ w
Interrupt factor
generation signal
(Internal signal,
nega-active)
Overflow signal,
Compare match signal
(Internal signal,
nega-active)
Interrupt request flag
(IRRTFH, IRRTFL)
Figure 9.7 Clear Interrupt Request Flag when Interrupt Factor Generation Signal is Valid
Interrupt request
flag clear
(2)
Interrupt Interrupt
(1)
Rev. 6.00 Aug 04, 2006 page 293 of 680
Section 9 Timers
Interrupt request
flag clear
Normal
REJ09B0145-0600