H838024 datasheet(321/697 Pages) RENESAS

321 / 697 page

Section 9 Timers

Rev. 7.00 Mar 10, 2005 page 279 of 652

REJ09B0042-0700

The term of validity of “Interrupt factor generation signal”

= 1 cycle of

φw + waiting time for completion of executing instruction

+ interrupt time synchronized with

φ = 1/φw + ST • (1/φ) + (2/φ) (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 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.

H838024 Datasheet(PDF) 321 Page - Renesas Technology Corp