Chapter 17
Watchdog (WDOG)
17.1 Introduction
The Watchdog Timer (WDOG) module is an independent timer that is available for
system use. It provides a safety feature to ensure that software is executing as planned
and that the CPU is not stuck in an infinite loop or executing unintended code. If the
WDOG module is not serviced (refreshed) within a certain period, it resets the MCU.
17.1.1 Features
Features of the WDOG module include:
• Configurable clock source inputs independent from the:
• bus clock
• Internal 32 kHz RC oscillator
• Internal 1 kHz RC oscillator
• External clock source
• Programmable timeout period
• Programmable 16-bit timeout value
• Optional fixed 256 clock prescaler when longer timeout periods are needed
• Robust write sequence for counter refresh
• Refresh sequence of writing 0xA602 and then 0xB480 within 16 bus clocks
• Window mode option for the refresh mechanism
• Programmable 16-bit window value
MC9S08PA4 Reference Manual, Rev. 5, 08/2017
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Summary of Contents for MC9S08PA4
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Page 196: ...Human machine interfaces HMI MC9S08PA4 Reference Manual Rev 5 08 2017 196 NXP Semiconductors ...
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Page 258: ...FTM Interrupts MC9S08PA4 Reference Manual Rev 5 08 2017 258 NXP Semiconductors ...
Page 294: ...Functional description MC9S08PA4 Reference Manual Rev 5 08 2017 294 NXP Semiconductors ...
Page 398: ...Resets MC9S08PA4 Reference Manual Rev 5 08 2017 398 NXP Semiconductors ...
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