AN3316 datasheet(16/42 Pages) STMICROELECTRONICS

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Device modes

AN3316

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Doc ID 18232 Rev 2

2.3.3

HW failure and error modes management

ME Provides a SAFE mode to manage either HW failure or errors caused by incorrect mode

transition configurations.

HW failure management

Device can manage some HW failure events to force SAFE mode transition instead of

generating a reset. This is possible through RGM (Reset Generation Module), which, for

examples, allows to configure following less-critical functional events:

●

FMPLL failure

●

FXOSC failure

●

CMU clock frequency higher/lower than reference

●

4.5 V low-voltage detected

●

code or data Flash fatal error

So, if one of these happens, the system enters into a pre-defined SAFE configuration from

which it may try to recover. It is also possible that SAFE transition is triggered by an interrupt

through the ME.

Following is an example that describes how crystal failure event can be managed:

Example

●

Current mode: DRUN with system clock = IRC (default)

●

Target mode: RUN0 mode with system clock = XOSC

●

XOSC failure event hapens

Steps

●

Configuration of RUN0 mode

–

ME_RUN0_MC.OSCON = 1

–

ME_RUN0_MC.SYSCLK = XOSC

●

Configuration of XOSC failure as SAFE transtition

–

ME_RGM_FERD.D_CMU_OLR = 1

–

ME_RGM_FEAR.AR_CMU_OLR = 0

●

Configuration of SAFE mode interrupt

–

ME_IM.M_SAFE = 1

●

XOSC failure event hapens

●

Software Transition request

–

ME_MCTL = RUN0 + KEY

–

ME_MCTL = RUN0 + INVERTED KEY

●

SAFE mode transition forced and interrupt generated

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