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R01UH0336EJ0102 Rev.1.02
Page 302 of 1538
Jul 17, 2014
V850E2/PG4-L
Section 8 Reset Controller
(2)
LVI Operation
Monitoring of the power supply voltage for the internal regulator after setting
the LVICNT bit to 1 can be used to generate an interrupt signal (INTLVI) or a
reset signal (LVIRES) in accord with the setting of the LVICNT.LVIMD bit when
the power supply voltage for the internal regulator falls below the prescribed
detection voltage.
(a) Using the LVI for the Output of Reset Signals
<Starting LVI operation>
1. Set the interrupt controller so that the interrupt (INTLVI) is masked.
2. Set the LVICNT.LVICNT bit so that a detection voltage exists.
3. Software handles at least 350
s of waiting time.
4. Test the value of the LVISF.LVISF bit to confirm that the voltage currently
being supplied is above the detection level.
5. Set the LVICNT.LVIMD bit to 1 (selecting the output of a reset signal).
Caution
After the LVICNT.LVIMD bit has been set to 1, further changes to the LVICNT
register are not possible until the generation of a request for a different type of
reset.
<Stopping LVI operation>
Stopping LVI operation is not possible except through the generation of a reset
of a different type.
Figure 8-6
Example of LVI Operation (when the LVICNT.LVIMD Bit = 1)
Time
Delay
Power supply
voltage
LVICLR
LVIRES
LVI detection voltage
4.5 V
Internal reset signal
LVI enable
▲LVI enable
*
*
Note:
*
If the signal falls below the voltage for guaranteed operation, the input of an external reset will be required.
Delay
Delay
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