CSD 3.5 counts to capacitance and temperature response

[Anonymous]

I'm using the PSoC5 LP Development Kit and try to implement the CSD for capacitive sensing.

   

Due to current research i found some hints how to calculate the capacitance from the counts.

   

Like this one:

   

http://www.cypress.com/knowledge-base-article/calculating-resolution-cy8c21x34-capsense-csd-kba82521

   

I've some problems to use this formula.

   

Since i'm using IDAC Sourcing there is no value for Bleed resistance.

   

In addition i'm not sure how to evaluate the average switching frequency of the sensor.

   

Are there any documentation about the measurement procedure of the controller?

   

So in general it should be possible to deduce that formula from the controller working procedure,

   

with knowledge of the systems capacitance.

       

The second topic concerns the temperature dependence of the system (without any plugged sensors).

   

I found that the board itself is not stable to changes in temperature and humidity level.

   

Could you please explain the origin of this drift?

[Bob_Marlowe]

Welcome in the forum, Christian!

   

Your questions are rather specific, so to get a reliable answer, I would suggest to contact Cypress directly.

   

At top of this page "Design Support -> Create a Support Case" and ask your questions there. Please be so kind to post the answers here in the forum to keep us informed.

       

Bob

   

PS: Where in Germany are you located? I live near Bremen.