NEC 78GK0S/K 1+ Series, Примечание к применению

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APPENDIX A PROGRAM LIST
z
main.c (C language version)
/*****************************************************************************
NEC Electronics 78K0S/KB1+
******************************************************************************
78K0S/KB1+
Sample program
******************************************************************************
Watchdog
timer
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<<History>>
2007.6.--
Release
******************************************************************************
<<Overview>>
This sample program presents an example of using the watchdog timer function.
The overflow time of the watchdog timer is set to 131.07 ms by counting the 8
MHz fx and runaway detection is performed. (fx: system clock source)
After completion of the initial settings, LED1 blinks every 120 ms and blinks
every 60 ms when the switch is pressed.
Here, a reset is generated by the watchdog timer at a 50% chance of occurrence,
depending on the timing at which SW is pressed, and LED2 lights, because the
watchdog timer is cleared about 70 ms after the interrupt of the SW input was
generated.
# Normally, an overflow should be avoided by clearing the watchdog timer at
the beginning and end of an interrupt.
<Principal setting contents>
- Declare a function run by an interrupt: INTP1 -> fn_intp1()
- Select fx as the watchdog timer (WDT) count clock and
set the overflow time to 131.07 ms
- Set the low-voltage detection voltage (VLVI) to 2.85 V +-0.15 V
- Generate an internal reset signal (low-voltage detector) when VDD < VLVI
after VDD >= VLVI
- Set the CPU clock frequency to 4 MHz
- Clear the watchdog timer about every 120 ms in the main loop
- Clear the watchdog timer about 70 ms after the interrupt of the switch
input was generated and clear the watchdog timer about every 60 ms if the
switch input continues thereafter
- Set the valid edge of external interrupt INTP1 to falling edge
- Set the chattering removal time during switch input to 10 ms
<SW input and LED1>
+----------------------------+
| SW | LED1 |
| (P43) | (P20) |
|-------|--------------------|
| OFF | Blink every 120 ms |
|-------|--------------------|
| ON | Blink every 60 ms |#
+----------------------------+
# A reset is generated by WDT at a 50% chance of occurrence when SW is
turned on.
Application Note U18847EJ1V0AN
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