Cypress F2MC-8FX Series Application Note - Page 7
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4
Usage and Examples
Functions and examples for watchdog timer
This chapter describes the usage of watchdog timer and gives some examples.
4.1
Functions and Operations of Watchdog Timer
Please write certain values to NVR flash area address FFBE
mode. See
Table 1
The Watchdog Timer has two operate modes as below:
Software watchdog
Write "A596
" (enable software watchdog timer) to the address FFBE
1.
H
are copied to the watchdog timer selection ID register WDTH/WDTL (0FEB
The watchdog timer is activated when "0101B" is written to the watchdog control bits of the watchdog timer
2.
control register (WDTC: WTE3 to WTE0) for the first time after a reset. The count clock switch bits of the
watchdog timer register (WDTC: CS1, CS0, CSP) should also be set at the same time.
3.
Once the watchdog timer is activated, a reset is the only way to stop its operation. Please clear watchdog
counter in a specified intervals regularly depend on the setting of WDTC: CS1, CS0, CSP. Refer to Table 3-1 for
detailed interval time.
Hardware watchdog
Write "A597
" (WDT can be stopped in a standby mode) or any other value (WDT is enabled in every mode)
1.
H
except than "A596
watchdog timer selection ID register WDTH/WDTL (0FEB
2.
The hardware watchdog timer starts automatically after a reset and cannot be stopped. Please clear its counter
at specified intervals regularly to avoid generates a watchdog timer reset.
3.
This timer is cleared by reset and resumes operation after the reset.
Please note that the watchdog timer is cleared at the same time as the timer selected as the count clock (timebase
timer or watch prescaler) is cleared. For this reason, the watchdog timer cannot function as such, if the software is set
to clear the selected timer repeatedly during the interval time of the watchdog timer
www.cypress.com
for detailed settings of mode choose.
" or "A597
" to the address FFBE
H
H
Document No. 002-05336 Rev.*A
F²MC-8FX Family, MB95200H/210H Series Watchdog Timer
and FFBF
to choose the watchdog timer operation
H
H
and FFBF
H
/0FEC
H
and FFBF
on the flash memory, which are copied to the
H
H
/0FEC
) after a reset.
H
H
on the flash memory, which
H
) after a reset.
H
6