Datasheet

78K0/Ix2 CHAPTER 22 LOW-VOLTAGE DETECTOR
R01UH0010EJ0500 Rev.5.00 638
Feb 28, 2012
22.4.2 When used as interrupt
(1
) When LVI default start function stopped is set (LVISTART = 0)
When starting operation
<1> Mask the LVI interrupt (LVIMK = 1).
<2> Set the LVI detection voltage using bits 3 to 0 (LVIS3 to LVIS0) of the low-voltage detection level
selection register (LVIS).
<3> Clear bit 1 (LVIMD) of LVIM to 0 (generates interrupt signal when the level is detected)
(default value).
<4> Set bit 7 (LVION) of LVIM to 1 (enables LVI operation).
<5> Use software to wait for an operation stabilization time (10
s (MAX.)).
<6> 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, at bit 0
(LVIF) of LVIM.
<7> Clear the interrupt request flag of LVI (LVIIF) to 0.
<8> Release the interrupt mask flag of LVI (LVIMK).
<9> Execute the EI instruction (when vector interrupts are used).
Figure 22-6 shows the timing of the interrupt signal generated by the low-voltage detector. The numbers in this
timing chart correspond to <1> to <8> above.
When stopping operation
Either of the following procedures must be executed.
When using 8-bit memory manipulation instruction:
Write 00H to LVIM.
When using 1-bit memory manipulation instruction:
Clear LVION to 0.