Capsense SNR problem

[bugkiller]

Hi,

My custom board usesCY8C4248LQI-BL553 and I got troubled some hardfault issue. So I start capsense tuner to find out what is going on and got SNR value(signal noise ratio). The result is 38.37 and I think it is pretty low value compare with my CY8CKIT-042 development kit(which is 180). 

The question is : Is it really low value for capsense? Is there limited guideline for capsense SNR? If it so, is there any way to reduce SNR?  

Best regards, BK.

[LinglingG_46 · Accepted solution]

Hi

Q: Is it really low value for capsense? Is there limited guideline for capsense SNR? If it so, is there any way to reduce SNR?  

A: I think it is not low value for capsense. We should ensure the SNR value is Greater or Equal to 5:1.

More about the proximity capsense tuning, please refer to the linker:

https://www.infineon.com/dgdl/Infineon-AN92239_Proximity_Sensing_with_CapSense-ApplicationNotes-v03_...

What do you mean about the  hardfault issue? I think it has no relationship with the Capsense NSR.

[bugkiller]

hi, @LinglingG_46 , thanks for the answer. So my project has LCD screen that controled by 6 different capsense button. But sometimes(in a weeks or days), capsense touch is dead, and that make me can't control LCD screen. So I hypothesized that Capsense was the cause. But I am not sure about that.

[LinglingG_46]

We should get the capsense parameters when it enters dead state, for example :rawcount,baseline,diffcount. If we have the debug interface, we can choose running to target to get the code position.