PSOC 6 Capsense Baseline Shift for CSD (Self-Capacitance) Proximity

[jacintal]

Hi, 

When I was looking at the CSD (Self-Capacitance) Proximity, I noticed a common shift in baseline despite no change in environment. The shift is much larger than the signal and the noise. I am wondering if there is any way to prevent this from occurring. 

Thank you!

[PandaS · Accepted solution]

Hi @jacintal,

Sensor Auto Reset :

A setting to prevent a sensor from reporting false touch status indefinitely due to system failure, or when a metal object is continuously present near the sensor. When Sensor Auto Reset is enabled, the Baseline is always updated even if the Difference Count is greater than the Noise Threshold. This prevents the sensor from reporting the ON status for an indefinite period of time. When Sensor Auto Reset is disabled, the Baseline is updated only when the Difference Count is less than the Noise Threshold.

Disable Sensor Auto Reset:

This option is set to “Disabled” to ensure that the baseline is not always updated. Updating the baseline may result in a reduced proximity-sensing distance when the target object approaches the sensor very slowly.

Please try to follow the above if your application is a slow approaching object towards the sensor. And do let us know the following:

1. A brief on your application

2. Is the baseline resetting even if the sensor is left untouched or unapproached? 

Warm Regards

Sobhit

[jacintal]

Hi Sobhit,

Thank you so much for the answer! 

For your first question, we are measuring the self-capacitance of elastic carbon composites to try to achieve proximity sensing. In our case, we don't need the sensor to capture light touches (significant bumps in self-capacitance) but rather small changes while an object is approaching it.

For the second question, baseline resetting does happen when the sensor is unapproached. While in the process of approaching the sensor with a piece of conductive material, CSD measurement does have an upward trend but seems insensitive (when >2cm distance from the sensor; sensor size is about 1x1cm). The resetting in CSX does happen as well but is less frequent. 

It would be great if you could provide us with some suggestions for setting the parameters for CSD especially (noise threshold etc.) to A. improve the proximity sensing range & B. get rid of the baseline resetting issue. If it's possible, could you also provide suggestions on the two points above for CSX? Thank you so very much and have a nice day!