CHAPTER 14 LOW-VOLTAGE DETECTOR
User’s Manual U18172EJ2V0UD
204
(2) When used as interrupt
•
When
starting
operation
<1> Mask the LVI interrupt (LVIMK = 1).
<2> Set the detection voltage using bits 3 to 0 (LVIS3 to LVIS0) of the low-voltage detection level select
register (LVIS).
<3> Set bit 7 (LVION) of LVIM to 1 (enables LVI operation).
<4> Use software to instigate a wait of at least 0.2 ms.
<5> Wait until “supply voltage (V
DD
)
≥
detection voltage (V
LVI
)” at bit 0 (LVIF) of LVIM is confirmed.
<6> Clear the interrupt request flag of LVI (LVIIF) to 0.
<7> Release the interrupt mask flag of LVI (LVIMK).
<8> Execute the EI instruction (when vector interrupts are used).
Figure 14-5 shows the timing of generating the interrupt signal of the low-voltage detector. Numbers <1> to
<7> in this figure correspond to <1> to <7> 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.
