HD6473847RHV Datasheet, PDF(266/546 Page) Renesas Technology Corp – Renesas 8-Bit Single-Chip Microcomputer H8 Family / H8/300L Super Low Power Series

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HD6473847RHV Datasheet, PDF (266/546 Pages) Renesas Technology Corp – Renesas 8-Bit Single-Chip Microcomputer H8 Family / H8/300L Super Low Power Series

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Section 9 Timers

For interrupt request flag is set right after interrupt request is cleared, interrupt process to one time

timer FH, timer FL interrupt might be repeated. (2 in figure 9.6) Therefore, to definitely clear

interrupt request flag in active (high-speed, medium-speed) mode, clear should be processed after

the time that calculated with below (1) formula. And, to definitely clear timer overflow flag and

compare match flag, clear should be processed after read timer control status register F (TCSRF)

after the time that calculated with below (1) formula.

For ST of (1) formula, please substitute the longest number of execution states in used instruction.

(10 states of RTE instruction when MULXU, DIVXU instruction is not used, 14 states when

MULXU, DIVXU instruction is used)

In subactive mode, there are not limitation for interrupt request flag, timer overflow flag, and

compare match flag clear.

The term of validity of âInterrupt source generation signalâ

= 1 cycle of ÏW + waiting time for completion of executing instruction

+ interrupt time synchronized with Ï

= 1/ÏW + ST Ã (1/Ï) + (2/Ï) (second).....(1)

ST: Executing number of execution states

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 reading the timer control status register F (TCSRF), clear the timer overflow flags

(OVFH, OVFL) and compare match flags (CMFH, CMFL).

4. Enable interrupts (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.

Rev. 7.00 Mar. 08, 2010 Page 234 of 510

REJ09B0024-0700

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