MPC57xx FCCU state transition

[jinjingyang]

Hi, community,

I have a question on FCCU state transition.

If FCCU enters FAULT state from ALARM state and functional reset is triggered by FCCU FAULT state, what's the next state for MCU and FCCU?

If a fault in FCCU is configured as the following:NCF[14], SWT_0, on MPC5748G.

NCF_CFG = 1; sw recoverable fault;

NCFS_CFG = 1; fault reaction is short functional reset

NCF_E = 1;   fault channel is enabled

NCF_TOE = 1, timeout is enabled for alarm state

IRQ_ALARM_EN = 1, enable alarm interrupt for this fault

NMI_EN = 0;   NMI disabled for this fault

EOUT_SIG_EN = 0; error signal output disabled

I enabled SWT_0 and didn't refresh the watchdog.

The FCCU enters ALARM state and then entering FAULT state.

At this moment, MCU reset occurred. But FCCU is not reset by MCU short functional reset, it's still in FAULT state?

Or FCCU moves from FAULT state to ALARM state, and MCU has another time window of FCCU_NCF_TO to recover faults. If MCU can clear faults within this time window, it can go back to NORMAL state.

Otherwise, the FCCU moves to FAULT state again and MCU reset is triggered again.

Am I right about the above description?

If change above settings to:

NCFS_CFG = 0; no reset on FAULT state.

The MCU is not reset even though FCCU is in FAULT state. And I can see FCCU is transitioning between FAULT state and ALARM state. It's clear that FCCU moves to ALARM state when ALARM timeout occurred.

But it's not clear what's the condition for FCCU to move from FAULT state to ALARM state?

I tried to debug but because it's across MCU reset and many registers information may not be accurate.

Regards,

Jason Yang

[petervlna]

Hi,

If FCCU enters FAULT state from ALARM state and functional reset is triggered by FCCU FAULT state, what's the next state for MCU and FCCU?

MCU -> reset

FCCU -> Normal

I enabled SWT_0 and didn't refresh the watchdog.

The FCCU enters ALARM state and then entering FAULT state.

At this moment, MCU reset occurred. But FCCU is not reset by MCU short functional reset, it's still in FAULT state?

FCCU module is reset by any reset. What is not reset is PBRIDGE where the registers for FCCU are located.

FCCU state machine is reset and it will start from normal state.

If the fault source is still present (I mean active fault line to FCCU) then the FCCU will go after reset to the Alarm state.\

If the fault signal is not active, FCCU will be in normal state and will only report the previous fault in NCFSx registers. But since the fault signal is not active FCCU has no reason to go into ALARM state.

If change above settings to:

NCFS_CFG = 0; no reset on FAULT state.

The MCU is not reset even though FCCU is in FAULT state. And I can see FCCU is transitioning between FAULT state and ALARM state. It's clear that FCCU moves to ALARM state when ALARM timeout occurred.

But it's not clear what's the condition for FCCU to move from FAULT state to ALARM state?

Hmm from fault to Alarm. I can't think of such situation.

I wonder if that's even safe + you have FOSU which will reset the device if no action is taken.

regards,

Peter