Datasheet

78K0/Kx2-L CHAPTER 22 LOW-VOLTAGE DETECTOR

R01UH0028EJ0400 Rev.4.00 690

Sep 27, 2010

Figure 22-11. Example of Software Processing After Reset Release (2/2)

• Checking reset source

Yes

Check reset source

Power-on-clear/external

reset generated

Reset processing by

watchdog timer

Reset processing by

low-voltage detector

Yes

WDTRF of RESF

LVIRF of RESF

Operation example 2: When used as interrupt

Interrupt requests may be generated frequently.

Take the following action.

Confirm that “supply voltage (V

DD) ≥ LVI detection voltage (VLVI)” when detecting the falling edge of VDD, or

“supply voltage (V

DD) < LVI detection voltage (VLVI)” when detecting the rising edge of VDD, in the servicing routine

of the LVI interrupt by using bit 0 (LVIF) of the low-voltage detection register (LVIM). Clear bit 1 (LVIIF) of interrupt

request flag register 0L (IF0L) to 0.

For a system with a long supply voltage fluctuation period near the LVI detection voltage, take the above action

after waiting for the supply voltage fluctuation time.

Remark If bit 2 (LVISEL) of the low voltage detection register (LVIM) is set to “1”, the meanings of the above words

change as follows.

• Supply voltage (V

DD) → Input voltage from external input pin (EXLVI)

• Detection voltage (V

LVI) → Detection voltage (VEXLVI = 1.21 V)