CapSense Guard Sensor Manual Tuning

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taas_3144281
Level 5
Level 5
Distributor - Marubun (Japan)
25 sign-ins 50 replies posted 25 replies posted

Hi.

I use Guard Sensor.

I am trying to prevent false detection due to liquid flow or wet cloth.

I want to Manual Tuning the guard sensor.

So is there a recommended tuning method?

Kit : CY8CKIT-149

Tool : PSoC Creator4.2

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1 Solution

Dear taas_3144281

The Guard sensor should be tested/ tuned  in the same environment as your end application.

Let us say you want to tune your guard sensor such that it should reject water flowing on your board. In that case, you need to test by actually pouring the liquid of interest (salt water/ with minerals/ distilled water/ hot water etc) on the board and observe the signals. Then you need to set the thresholds accordingly. As said earlier, when you touch the button, it should not trigger the guard sensor. This should also be taken care of.

Regards,

Bragadeesh

Regards,
Bragadeesh

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

Hi taas_3144281​,

Guard sensor can be tuned similar to any other buttons. (Manual tuning is recommended)

The Guard sensors need to be tuned in such a way that touching the buttons should not trigger the guard. This will cause the buttons to be disabled. It should be triggered only when the liquid stream flows through it.

You can follow the same tuning guidelines mentioned in the CapSense design guide  (Pg 51) to tune a guard sensor.

https://www.cypress.com/file/46081/download

Regards,

Bragadeesh

Regards,
Bragadeesh
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taas_3144281
Level 5
Level 5
Distributor - Marubun (Japan)
25 sign-ins 50 replies posted 25 replies posted

Dear BragadeeshV_41

Thank you for your answer.

What is the recommended guard sensor evaluation environment?

In the case of a normal touch button, use a pseudo finger to evaluate.

Best Regards,

asanuma

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Dear taas_3144281

The Guard sensor should be tested/ tuned  in the same environment as your end application.

Let us say you want to tune your guard sensor such that it should reject water flowing on your board. In that case, you need to test by actually pouring the liquid of interest (salt water/ with minerals/ distilled water/ hot water etc) on the board and observe the signals. Then you need to set the thresholds accordingly. As said earlier, when you touch the button, it should not trigger the guard sensor. This should also be taken care of.

Regards,

Bragadeesh

Regards,
Bragadeesh
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taas_3144281
Level 5
Level 5
Distributor - Marubun (Japan)
25 sign-ins 50 replies posted 25 replies posted

Dear Bragadeesh-san

Thank you for your answer.

I test the guard sensor assuming a case.

Is there an initial reference value when setting the guard sensor threshold?

Does the guard sensor need to be enabled if normal touch buttons are not affected?

Best Regards,

asanuma

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Hi taas_3144281​,

The guard sensor initial setting should be 80 % of difference signal when liquid is poured on it.

Yes, the guard sensor should be scanned and checked all the times to detect liquid flow.


Regards,

Bragadeesh

Regards,
Bragadeesh
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taas_3144281
Level 5
Level 5
Distributor - Marubun (Japan)
25 sign-ins 50 replies posted 25 replies posted

Dear Bragadeesh-san

Thank you for your answer.

I am glad that I do not have to worry about those for Guard sensor.

Best Regards,

asanuma

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