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When is Kinetis reset pin driven low by microcontroller?

Question asked by George Sosnowski on Apr 5, 2016
Latest reply on Apr 7, 2016 by Kerry Zhou

We want to use the MK22FN512CAP12R in a design.

One clarification that was needed was the behavior of the RESET_B pin and when it is driven by the microcontroller.

From the reference manual, it’s clear that on PowerOn Reset, it is driven.

But it’s unclear if there are other conditions that may cause the RESET_B pin to be driven by the microcontroller, from the following statement in the reference manual:

For all reset sources except a VLLS Wakeup that does not occur via the RESET pin, the

RESET pin is driven low by the MCU for at least 128 bus clock cycles and until flash

initialization has completed.


However, it looks at least for the WDOG, the statement below from the reference manual indicates this behavior is configurable. We’re just concerned what other sources there could be.

The watchdog consists of a counter that if allowed to overflow, forces an

internal reset (asynchronous) to all on-chip peripherals and optionally assert the RESET

pin to reset external devices/circuits.