CHAPTER 17 LOW-VOLTAGE DETECTOR
Preliminary User’s Manual U19014EJ1V0UD
442
17.4.2 When used as interrupt
(1) When detecting level of supply voltage (V
DD
)
•
When
starting
operation
<1> Mask the LVI interrupt (LVIMK = 1).
<2> Set the detection voltage using bit 0 (LVIS0) of the low-voltage detection level selection register (LVIS).
<3> Set bit 7 (LVION) of LVIM to 1 (enables LVI operation).
<4> Use software to wait for an operation stabilization time (10
µ
s (MAX.)).
<5> Confirm that “supply voltage (V
DD
)
≥
detection voltage (V
LVI
)” at bit 0 (LVIF) of LVIM.
<6> Clear the interrupt request flag of LVI (LVIIF) to 0.
<7> Release the interrupt mask flag of LVI (LVIMK).
<8> Clear bit 1 (LVIMD) of LVIM to 0 (generates interrupt signal when supply voltage (V
DD
) < detection
voltage (V
LVI
)) (default value).
<9> Execute the EI instruction (when vector interrupts are used).
Figure 17-6 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.
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