When Used As Interrupt - NEC 78K0 Series User Manual

24.4.2 When used as interrupt

(1) When detecting level of supply voltage (V
• When starting operation
<1> Mask the LVI interrupt (LVIMK = 1).
<2> Clear bit 2 (LVISEL) of the low-voltage detection register (LVIM) to 0 (detects level of supply voltage
(V )) (default value).
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<3> Set the detection voltage using bits 3 to 0 (LVIS3 to LVIS0) of the low-voltage detection level selection
register (LVIS).
<4> Set bit 7 (LVION) of LVIM to 1 (enables LVI operation).
<5> Use software to wait for an operation stabilization time (10
<6> Confirm that "supply voltage (V
<7> Clear the interrupt request flag of LVI (LVIIF) to 0.
<8> Release the interrupt mask flag of LVI (LVIMK).
<9> Clear bit 1 (LVIMD) of LVIM to 0 (generates interrupt signal when supply voltage (V
voltage (V )) (default value).
LVI
<10> Execute the EI instruction (when vector interrupts are used).
Figure 24-7 shows the timing of the interrupt signal generated by the low-voltage detector. The numbers in
this timing chart correspond to <1> to <9> 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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CHAPTER 24 LOW-VOLTAGE DETECTOR
)
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) ≥ detection voltage (V
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Preliminary User's Manual U17260EJ3V1UD
µ
s (MAX.)).
)" at bit 0 (LVIF) of LVIM.
LVI
) < detection
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