According to the Hari's reply on below thread, I need to set up a reference sensor for environmental compensation on CapSense CSD library v2.6 in my current design, for example if I set up this reference sensor base on CY8CKIT-022 CapSense Liquid Level Sensing Shield, what I need to do in terms of software side and also hardware side?
Thanks and regards,
There are two approaches for environmental compensation.
1. Hardware way -
This requires an additional reference sensor of the same dimensions as the rest of the liquid level sensing sensors - if you see the 022 kit, they are parallelogram-shaped sensors and so, the reference sensor must also be of the same shape and area.
Now, the sensor must be placed in a location where it is subjected to the same environmental conditions but is not in contact with any liquid ever.
If this is possible, you can go ahead and implement this and use the raw counts of this to compare the signal level of the other sensors.
The firmware in such a design is simple and straightforward.
2. Firmware compensation -
This method does not require any additional sensor, instead, it uses the adjacent sensors to compare the signal level.
Since the environmental changes impact all the sensors in a similar way, you can see the difference in raw count of adjacent sensors to determine the signal level.
Note that this method will require some tuning at your end to determine the maximum variation in raw counts over the operating temperature range and appropriate thresholds must be set to make sure that the system works correctly over the entire range.
I would also like to mention that in the firmware, it is recommended to use the latest CapSense component - CapSense V7.0 for new designs