Sensitivity Guard Sensor

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Anonymous
Not applicable

Hello everyone, in my project I use cy8cmbr3110. I'm having problems with the sensitivity of the guard, I need to decrease the sensitivity of the guard. My settings for the guard are:

Hardware:

Guard sensor thickness: 2mm.

Overlay = 4mm glass.

EZ-Click:

Sensitivity (fF) = 400.

Automatic threshold = Enabled.

IIR filter = Enabled.

Median Filter = Enabled.

Debounce: 3.

Enable EMC noise immunity: Disabled.

With these settings it is still possible to decrease the sensitivity of the guard without changing the hardware?

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1 Solution

Hello,

Increasing the resistor value can affect the signal level. Since your Cp value is within limits, increasing the resistor value wouldn't affect your signal much. But make sure the guard sensor capacitor is charging and discharging completely. Also in your EZ- Click, make sure that your SNR is greater than equal to 5:1. If the SNR is greater than this ratio, then there wouldn't be any problem.

Also mention the series resistor value you have used. Do the SNR test and post your results so that it will be helpful for the community users.

Regards,

Bragadeesh.

Regards,
Bragadeesh

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

Hello,

Can you lease tell me what is the Cp value of your guard sensor? Sensitivity will be high if the Cp value is very less.

Disable automatic threshold and increase the threshold of the guard sensor by writing the threshold value directly into the registers.

If your environment is too noisy, you can turn on the EMC noise immunity feature. But this feature works only if automatic threshold feature is disabled.

What is the dielectric material you are using( mention dielectric constant)? . Materials with high dielectric constant results in higher sensitivity of sensors.

Also please clarify if hatch pattern was implemented as per recommendations.

Regards,

Bragadeesh

Regards,
Bragadeesh
Anonymous
Not applicable

Hello,

Can you lease tell me what is the Cp value of your guard sensor? Sensitivity will be high if the Cp value is very less.

Cp value guard sensor: 30

Disable automatic threshold and increase the threshold of the guard sensor by writing the threshold value directly into the registers.

I used the maximum value (200) for the threshold of the guard sensor, but it still remains very sensitive.

If your environment is too noisy, you can turn on the EMC noise immunity feature. But this feature works only if automatic threshold feature is disabled.

I activated EMC noise immunity, but the sensitivity did not decrease.

What is the dielectric material you are using( mention dielectric constant)? . Materials with high dielectric constant results in higher sensitivity of sensors.

Overlay Material : Glass (Standard).

Dielectric constant : 8.

Also please clarify if hatch pattern was implemented as per recommendations.

I followed all recommendations for hatch pattern.

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Hi,

Can you share your layout files in Gerber format?

Regards,

Bragadeesh

Regards,
Bragadeesh
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Anonymous
Not applicable

Hello,

Attached is the gerber file.

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Hello,

You could use the following firmware technique, instead of guard sensor.

You can configure the host in such a way that the sensor status would be rejected, if two or more sensors are triggered at the same time. (Two or more sensors would be activated when there is liquid pool on the board)

I assume that your application does not require two sensors to be detected simultaneously.

I hope this helps.

Thanks,

Shanmathi

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Anonymous
Not applicable

,

I'll try this. But this way, I have to disable Auto Reset to continue detecting the liquid in the panel. In my project, auto reset must be enabled.

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Anonymous
Not applicable

I increased the value of the resistor in series with the guard sensor, with that it decreased the sensitivity. Is this advisable? Can I have problems with this change?

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Hello,

Increasing the resistor value can affect the signal level. Since your Cp value is within limits, increasing the resistor value wouldn't affect your signal much. But make sure the guard sensor capacitor is charging and discharging completely. Also in your EZ- Click, make sure that your SNR is greater than equal to 5:1. If the SNR is greater than this ratio, then there wouldn't be any problem.

Also mention the series resistor value you have used. Do the SNR test and post your results so that it will be helpful for the community users.

Regards,

Bragadeesh.

Regards,
Bragadeesh
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