TMS570LS1114: How to test external Watchdog Reset

Christian Sch.

Part Number: TMS570LS1114

Hello,

in our application we use the TMS570LS1114 together with the Infineon TLF35584, that combines voltage supply and monitoring as well as watchdog functions as a system basis chip or PMIC. The TLF35584 has one Reset Output (called ROT), that is driven low in case of invalid MCU voltages or in case of watchdog failures, so it has to be connected to pin nPORRST of TMS570LS1114.

The same situation should be even with the TI TPS65381A, because this device also combines under-volatge reset and watchdog reset via its pin NRES, so it also has to be connected to nPORRST.

Both devices can not be connected to the warm reset input nRST of TMS570LS1114.

To detect latent faults in the watchdog circuit we have to test the watchdog at power-up. Is there any suggested way to store the information, that the watchdog test is performed, and to keep this information during the external activated power-on-reset via the nPORRST pin? SYSESR:PORST does not allow to detect the difference. It seems that RAM, even in Power Domain PD1, cannot be used to sustain information during PORRST, because it has to be initialized after reset to satisfy the ECC.

So how to do?

Thanks

Christian

9 months ago

0 Ralph Jacobi 9 months ago

TI__Guru*** 130250 points

Hello Christian,

Our expert for this topic is out on local holiday and will be back on Wednesday, please wait for their feedback until then, thank you.

Best Regards,

Ralph Jacobi

0 jagadish gundavarapu 9 months ago in reply to Ralph Jacobi

TI__Mastermind 49615 points

Hi Christian,

Can you please verify a similar issue that we handled recently?

(+) RM48L952: External voltage supervision of hercules rm 48 with TPS37042A3OFDDFRQ1 - Arm-based microcontrollers forum - Arm-based microcontrollers - TI E2E support forums

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Thanks & regards,
Jagadish.

0 Christian Sch. 9 months ago in reply to jagadish gundavarapu

Prodigy 70 points

Hi Jagadish,

your mentioned topic is similar, but still different. It handles just an external voltage supervision without included external watchdog and it has several reset outputs. In my case there is only one combining reset output. To verify the complete ability of the external supervisions to perform the reset of the controller I think it is necessary actually to do the reset of the Hercules. Otherwise it is not to 100 % sure, that the reset line at all is still functional.

So again the question: Is there any possibility in the TMS570LS1114 to retain information of performing the test during the power-on-reset with all voltages working normally all the time? For sure the (EEPROM emulated) Flash Memory cannot be used, because it would lead to a lot of write-cycles during life-time.

Thanks and regards,

Christian

0 jagadish gundavarapu 9 months ago in reply to Christian Sch.

TI__Mastermind 49615 points

Hi Christian,

Christian Sch. said:
So again the question: Is there any possibility in the TMS570LS1114 to retain information of performing the test during the power-on-reset with all voltages working normally all the time?

There won't be any possible mechanism for this.

I think the only possible way is:

We have SYSESR register to provide the reset cause.

But here we have to find out whether we are doing reset for testing purpose or it happens automatically. For this purpose we have to use EEPROM, and we have to write one bit as SET if we are testing.

I mean if this test bit SET and RESET bit in SYSESR register set then we can assume it as testing otherwise not a testing. I think this is the only possible way.

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Thanks & regards,
Jagadish.