ml670100 Oki Semiconductor, ml670100 Datasheet - Page 88

• Manufacturer Part Number: ml670100
• Description: Ml670100 Is A High-performance 32-bit Microcontroller
• Manufacturer: Oki Semiconductor

6.3.3
6.3.4
6-8
If f is the system clock (SYSCLK) frequency in MHz, t WDT, the time in microseconds that the
Watchdog Timer (WDT) internal counter takes to overflow, is given by the following formula.
Because clearing the Watchdog Timer (WDT) internal counter does not affect the contents of
the Time Base Counter (TBC), there is a maximum negative error of one input clock cycle.
For a system clock (SYSCLK) frequency of 16 MHz and an input clock of 256TBCCLK (m =
256), these two formulas yield the following results.
Figure 6.6 illustrates WDT watchdog timer operation for a program operating normally (a) and
one that runs out of control (b).
Figure 6.7 gives three possible patterns for runaway programs.
Time to Overflow
WDT Watchdog Timer Operation
t WDT = m x 4096 / f [us]
where m is the number from the clock input name - 32 from 32TBCCLK, etc.
delta WDT = m / f [us]
t WDT = 65.536 ms
delta WDT = 16 [us]