INTERNAL SPECIFICATIONS

4.5.2.5.8Caution about use of timer counters 0 and 1 when setting software power down mode

When setting sofware power down mode, if the value of a timer counter by which a timer interrupt is set is immediately before overflow, the software power down mode can not be set.

(Example)

Timer 0 is in mode 1 of external clock.

Content of timer 0 is "FF".

Interrupt by timer 0 is enabled.

TO pin is "1".

If the above conditions all are established, the sofware power down mode cannot be set. This is because the AND output, shown as (A) of Fig. 4-19, becomes "1" when the software power down mode is set and timer interrupt is generated.

In this case, set the software power down mode after setting the TO pin to "0".

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Sonic Alert msm85c154hvs, msm83c154s, msm80154s user manual Internal Specifications