Imprecision in PSOC3 watchdog(WDT) time

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CrVi_1101311
Level 3
Level 3
10 replies posted 5 replies posted 5 questions asked

Hello.

I have configured the WDT in a PsoC3 as CYWDT_128_TICKS / * WATCHDOG: 256 ... 384msg * /
And in "some" equipment the reset is generated from 212msg-225msg. Very low value respect configuration.
What is the real precision of the WDT?
Could the chip be damaged by an ESD or similar that produces this phenomenon?.
Could be affected in solder process?

Is this normal behavior?

Thanks.

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1 Solution
BragadeeshV
Moderator
Moderator
Moderator
First question asked 1000 replies posted 750 replies posted

Hi CrVi_1101311​,

The WDT block is sourced from ILO (CTW - 1Khz) which has an accuracy of -50 to +100 %. Therefore you find this inaccuracy range in the WDT interval. From the system reference guide and architecture TRM, when WDT is configured to CYWDT_128_TICKS, it is expected to have periods range at 256 – 384 ms.

Was there any specific event that caused this period to change?

To improve accuracy you can use the ILO trim component, details of which can be found at the following links:

https://www.cypress.com/documentation/component-datasheets/ilo-trim

https://www.cypress.com/documentation/code-examples/ce95328-1khz-ilo-trimming-psoc-35lp - Use PSoC Creator to get latest version of this example. (File > Code example)

Regards,

Bragadeesh

Regards,
Bragadeesh

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3 Replies
BragadeeshV
Moderator
Moderator
Moderator
First question asked 1000 replies posted 750 replies posted

Hi CrVi_1101311​,

The WDT block is sourced from ILO (CTW - 1Khz) which has an accuracy of -50 to +100 %. Therefore you find this inaccuracy range in the WDT interval. From the system reference guide and architecture TRM, when WDT is configured to CYWDT_128_TICKS, it is expected to have periods range at 256 – 384 ms.

Was there any specific event that caused this period to change?

To improve accuracy you can use the ILO trim component, details of which can be found at the following links:

https://www.cypress.com/documentation/component-datasheets/ilo-trim

https://www.cypress.com/documentation/code-examples/ce95328-1khz-ilo-trimming-psoc-35lp - Use PSoC Creator to get latest version of this example. (File > Code example)

Regards,

Bragadeesh

Regards,
Bragadeesh
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Thanks for the quick reply.

I did not know that it was so imprecise.
Does this mean that each device can have different Trim settings?
It doesn't seem like a good solution.
Thank you.

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Hi CrVi_1101311​,

Yes, we might have different trim settings for each device.

Regards,

Bragadeesh

Regards,
Bragadeesh
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