Fault monitoring of SWT0,SWT1 in MPC5746R

[kiranmuniraju]

Hi,

I need to do fault monitoring of SWT0 or SWT1 in MPC5746R to ensure that SWT module functionality is working or not. Monitoring of SWT should be in run time.

From Reference manual I understood that , FCCU can collect the NCF index for RESET or IRQ related to SWT. But if SWT module is failed, that status will not updated to FCCU. So in that scenario is there any possibility to check that SWT module is working or not..?

Can you please suggest any possible methods..?

Thanks

[petervlna]

Hi,

Yes the SWT in case of not updated counter register will inform FCCU about expire of watchdog and FCCU can react on fault.

The SWT module itself is tested by STCU BISTs. Online or Offline.

This will ensure the correct execution of SWT after every power on cycle.

These tests are implemented in HW so user don't have to control SWT functionality.

For more details refer to reference manual STCU2 chapter.

Peter

[kiranmuniraju]

Hi Peter,

Thanks for your quick reply.

As of my understanding SWT module will generate a NCF for RESET/IRQ when counter register overflow happened. So How FCCU can identify the counter register update failure. Is my understanding is correct or is there any mechanism to check the SWT fault in FCCU...?

[petervlna]

Hello,

I will explain it to you as you are quite confused.

SWT functionality is to count down from value loaded in (SWT_TO).

The SWT must be periodically updated from software.

If the update is not performed SWT will pull the failure line to FCCU ->NCFx

"How FCCU can identify the counter register update failure"

This makes no sense as you answered it yourself in sentence right before.

The fault is generated only if counter runs out. (Not updated)

Peter