PSOC_4 cap sense clock parameters...

[Tim_Shih]

Dear Receiver,

In the attached file, I use manual turning. But I meet two kinds of clock parameters make me feel confused.

1. "modulator clock frequency": how this parameter effect cap-sense performance ?! If I select higher clock or lower clock, what's the corresponding result ?! 

2. "sense clock frequency": how this parameter effect cap-sense performance ?! If I select higher clock or lower clock, what's the corresponding result ?! 

Besides, how to select the sense clock source ?! auto, direct, PRS8 and PRS12. how to select them in a proper way ?! 

In fact, I know these parameters are explained in the manual but I still feel so confused. So I asked my question in here.

Hope I can get your kindly feedback.

Thank you so much.

[MotooTanaka · Accepted solution]

Hi,

We can access the datasheet of a component from it's configuration window.

(There is a [ Datasheet ] button in the bottom left of the window)

Selecting the [ Datasheet ] button, we can open the datasheet

In the datasheet there are

(1) Modulator Clock Frequency

(2) Sense Clock

 

moto

 

 

[Tim_Shih]

Hi MotooTanaka,

Yes, I read this. But the thing make me feel confused is ...

If I select a higher frequency, what's the effect to cap sense ?!

If I select a lower frequency, what's the effect to cap sense ?!

For example, if the higher frequency, the higher cap sense sensitivity we can get.

Why not we always select the highest frequency (sense clock & modulator clock) ?!

Thank you so much.

[MotooTanaka]

Hi,

This is my understanding and I may be wrong or incomplete,

so proceed with a grain of salt.

The CapSense sensor is complete with the device (PSoC) and external electrode(s).

And the capacitance and resistance of the electrode(s) can vary.

So the "highest" frequency may not be sufficient for a particular electrode,

and you or the designer need to adjust the frequency and sensitivity depending on the application's requirement.

You may be able to get more information about CapSense from

https://www.infineon.com/cms/en/product/microcontroller/sensing-controller/capsense-controllers/?ter...

moto

[Tim_Shih]

Hi MotooTanaka,

Final 2 questions,,,

#1. What the external electrode(s) ?!

#2. Could I say "the higher clock frequency (no matter modulator or sense clock), the higher cap sense sensitivity we can get" ?!

ps: even I know maybe I can't reach the highest frequency because I also need to care about external electrode. 

Thank you so much.

[MotooTanaka]

Hi,

#1. What the external electrode(s) ?!

The external metal part, often a pattern in the PCB.

(For more details, please refer to the later document references)

#2. Could I say "the higher clock frequency (no matter modulator or sense clock), the higher cap sense sensitivity we can get" ?!

I think that basically yes, but the physical sensor circuit (capacitance, resistance, environment noise level, etc.) limit the value.

But, as we have "Auto Tuning" Mode in the CapSense Component, we don't have to run the math in the beginning to get a ballpark figure. 

Meantime, CapSense Tuner helps us actually measure/adjust those values.

I hope that the following documents will help you to understand the CapSense.

(1) CapSense Component Datasheet  (You've already read this)

(2) AN64846  Getting Started with CapSense

https://www.infineon.com/dgdl/Infineon-AN64846_Getting_Started_with_CapSense-ApplicationNotes-v26_00...

(3) AN85951 PSoC 4 and PSoC 6 MCU CAPSENSE design guide

https://www.infineon.com/dgdl/Infineon-AN85951_PSoC_4_and_PSoC_6_MCU_CapSense_Design_Guide-Applicati...

(4) AN210998 PSoC 4 Low-Power CapSense Design

https://www.infineon.com/dgdl/Infineon-AN210998_PSoC_4_Low-Power_CapSense_Design-ApplicationNotes-v0...

moto

Edited: Fixed a typo

[Tim_Shih]

Hi MotooTanaka,

Thank you for your kindly feedback!!

😀 ~