SN8F5708 datasheet(41/204 Pages) SONIX

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SN8F5708 Series

Reset and Power-on Controller

Datasheet Rev. 2.4

7.4 Watchdog Reset

Watchdog is a periodic reset signal generator for the purpose of monitoring the execution flow. Its

internal timer is expected to be cleared in a check point of program flow; therefore, the actual

reset signal would be generated only after a software problem occurs. Writing 0x5A to WDTR is the

proper method to place a check point in program.

WDTR = 0x5A;

Watchdog timer interval time = 256 * 1/ (Internal Low-Speed oscillator frequency/WDT Pre-scalar)

= 256 / (FILRC /WDT Pre-scaler) …sec

Internal low-speed

oscillator

WDT

pre-scaler

Watchdog interval time

FILRC =16 kHz

FILRC /4

256/(16000/4)=64ms

FILRC /8

256/(16000/8)=128ms

FILRC /16

256/(16000/16)=256ms

FILRC /32

256/(16000/32)=512ms

The operation mode of watchdog is configurable in options file:

Always mode counts its internal timer in all CPU operation modes (normal, IDLE, SLEEP);

Enable mode counts its internal timer during CPU stays in normal mode, and it would not trigger

watchdog reset in IDLE and STOP modes;

Disable mode suspends its internal timer at all CPU modes, and the watchdog would not trigger in

this condition.

When watchdog is operating in always mode, the system will consume additional power.

SN8F5708 Datasheet(PDF) 41 Page - SONiX Technology Company