UPD78F1502AGK-GAK-AX Datasheet, PDF (837/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 24 LOW-VOLTAGE DETECTOR
(2) When detecting level of input voltage from external input pin (EXLVI)
• When starting operation
<1> Mask the LVI interrupt (LVIMK = 1).
<2> Set bit 2 (LVISEL) of the low-voltage detection register (LVIM) to 1 (detects level of input voltage from
external input pin (EXLVI)).
Clear bit 1 (LVIMD) of LVIM to 0 (generates interrupt signal when the level is detected) (default value).
<3> Set bit 7 (LVION) of LVIM to 1 (enables LVI operation).
<4> Use software to wait for the following periods of time (Total 210 μs).
• Operation stabilization time (10 μs (MAX.))
• Minimum pulse width (200 μs (MIN.))
<5> Confirm that “input voltage from external input pin (EXLVI) ≥ detection voltage (VEXLVI = 1.21 V (TYP.))”
when detecting the falling edge of EXLVI, or “input voltage from external input pin (EXLVI) < detection
voltage (VEXLVI = 1.21 V (TYP.))” when detecting the rising edge of EXLVI, 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> Execute the EI instruction (when vector interrupts are used).
Figure 24-10 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.
Caution Input voltage from external input pin (EXLVI) must be EXLVI < VDD.
• When stopping operation
Be sure to clear (0) LVION by using a 1-bit memory manipulation instruction.
R01UH0004EJ0501 Rev.5.01
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Jun 20, 2011