upd78f0114hgb-8es-a Renesas Electronics Corporation., upd78f0114hgb-8es-a Datasheet - Page 370

• Manufacturer Part Number: upd78f0114hgb-8es-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: Renesas Electronics Corporation.

21.4 Operation of Low-Voltage Detector
370
The low-voltage detector can be used in the following two modes.
The operation is set as follows.
(1) When used as reset
Used as reset
Compares the supply voltage (V
V
Used as interrupt
Compares the supply voltage (V
when V
DD
<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
<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> Confirm that “supply voltage (V
<6> Set bit 1 (LVIMD) of LVIM to 1 (generates internal reset signal when supply voltage (V
Figure 21-4 shows the timing of the internal reset signal generated by the low-voltage detector. The numbers
in this timing chart correspond to <1> to <6> above.
Cautions 1. <1> must always be executed. When LVIMK = 0, an interrupt may occur immediately
< V
When starting operation
When stopping operation
Either of the following procedures must be executed.
When using 8-bit memory manipulation instruction:
When using 1-bit memory manipulation instruction:
DD
register (LVIS).
voltage (V
LVI
Write 00H to LVIM.
Clear LVIMD to 0 first, and then clear LVION to 0.
.
< V
2. If supply voltage (V
LVI
after the processing in <3>.
signal is not generated.
.
LVI
)).
CHAPTER 21 LOW-VOLTAGE DETECTOR
DD
DD
) and detection voltage (V
) and detection voltage (V
DD
DD
)
User’s Manual U16961EJ4V0UD
)
detection voltage (V
detection voltage (V
LVI
LVI
LVI
LVI
), and generates an internal reset signal when
), and generates an interrupt signal (INTLVI)
)” with bit 0 (LVIF) of LVIM.
) when LVIMD is set to 1, an internal reset
DD
) < detection