CHAPTER 19 LOW-VOLTAGE DETECTOR
Preliminary User’s Manual U16846EJ1V0UD
327
(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 selection
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 it is checked that (supply voltage (V
DD
) > detection voltage (V
LVI
)) by bit 0 (L
VIF
) of LVIM.
<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 19-5 shows the timing of the interrupt signal generated by the low-voltage detector. The numbers in
this timing chart 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.
