upd78f9211grt2-jjg-a ETC-unknow, upd78f9211grt2-jjg-a Datasheet - Page 205

• Manufacturer Part Number: upd78f9211grt2-jjg-a
• Description: 8-bit Single-chip Microcontrollers
• Manufacturer: ETC-unknow

14.5 Cautions for Low-Voltage Detector
(V
<1> When used as reset
<2> When used as interrupt
<Action>
(1) When used as reset
(2) When used as interrupt
LVI
In a system where the supply voltage (V
In this system, take the following actions.
After releasing the reset signal, wait for the supply voltage fluctuation period of each system by means of a
software counter that uses a timer, and then initialize the ports (see Figure 14-6).
(a) Perform the processing
(b) In a system where the supply voltage fluctuation period is long in the vicinity of the LVI detection voltage, wait
Note For low voltage detection processing, the CPU clock speed is switched to slow speed and the A/D
), the operation is as follows depending on how the low-voltage detector is used.
The system may be repeatedly reset and released from the reset status.
In this case, the time from release of reset to the start of the operation of the microcontroller can be arbitrarily
set by taking action (1) below.
Interrupt requests may be frequently generated. Take (b) of action (2) below.
(V
(LVIM). Clear bit 1 (LVIIF) of interrupt request flag register 0 (IF0) to 0.
for the supply voltage fluctuation period, check that “supply voltage (V
LVIF flag and clear LVIIF flag to 0.
LVI
converter is stopped, etc.
)” in the servicing routine of the LVI interrupt by using bit 0 (LVIF) of the low-voltage detection register
Note
for low voltage detection. Check that “supply voltage (V
CHAPTER 14 LOW-VOLTAGE DETECTOR
DD
) fluctuates for a certain period in the vicinity of the LVI detection voltage
User’s Manual U16994EJ3V0UD
DD
) ≥ detection voltage (V
DD
) ≥ detection voltage
LVI
)” using the
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