UPD78F1502AGK-GAK-AX Datasheet, PDF (390/1031 Pages) Renesas Technology Corp – 16-Bit Single-Chip Microcontrollers

78K0R/Lx3
CHAPTER 8 WATCHDOG TIMER
CHAPTER 8 WATCHDOG TIMER
8.1 Functions of Watchdog Timer
The watchdog timer is mounted onto all 78K0R/Lx3 microcontroller products.
The watchdog timer operates on the internal low-speed oscillation clock.
The watchdog timer is used to detect an inadvertent program loop. If a program loop is detected, an internal reset
signal is generated.
Program loop is detected in the following cases.
• If the watchdog timer counter overflows
• If a 1-bit manipulation instruction is executed on the watchdog timer enable register (WDTE)
• If data other than “ACH” is written to WDTE
• If data is written to WDTE during a window close period
When a reset occurs due to the watchdog timer, bit 4 (WDRF) of the reset control flag register (RESF) is set to 1. For
details of RESF, see CHAPTER 22 RESET FUNCTION.
When 75% of the overflow time is reached, an interval interrupt can be generated.
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Jun 20, 2011