What about when the temperature changes in the capsense 5th GEN?

[NXTY_Tatebayasi]

Hi, community

According to the explanation in 5.3.2.3.1 of the capsense design guide, capsense seems to change the sensor raw count values due to environmental changes such as temperature and humidity .

【Questions】
1.  Is there any advantage to this in the 3rd and 4th vs. 5th generation capsense?
2.  Also, is there any indicator such as characteristic data (e.g. raw data /temp[°C]) for capsense raw counts with respect to temperature?

Best Regards,

Chihiro Tatebayashi

[PandaS · Accepted solution]

Hi @NXTY_Tatebayasi ,

1. Both in CSDv2(3rd & 4th Gen) and MSCv3(5th Gen) CapSense architecture, the raw counts change with the environment changes. 

2. There is no particular characteristic graph, but in case you want your system to be independent of these environmental effects. You can implement a reference sensor, which can be placed in the same environment as your required sensor, but its readings (raw counts) will be treated as baseline for your required sensor. 

Thanks and regards

Sobhit

[NXTY_Tatebayasi]

Hi, @PandaS  -san

Thank you for your reply.
What is the best way to see how much the baseline changes with temperature?
For example, can I record the baseline value at room temperature and infer that the capsense is operating normally from a certain range of values indicated by the raw count of the baseline (with nothing touched) when the ambient temperature changes?

Best Regards,

Chihiro Tatebayashi

[NXTY_Tatebayasi]

Hi, @PandaS -san

Thank you for your reply and  explaining them to me in detail.
I have understood them!

Best Regards,

Chihiro Tatebayashi

[PandaS]

Hi @NXTY_Tatebayasi -San,

The relation between raw counts and the temperature of the environment is not constant, it varies with tuning parameters. So, in case you want to properly infer the temperature effect on the CapSense Sensor, read the absolute Cp value of the sensor at a particular temperature with the help of BIST APIs.

Next, you can vary the temperature slowly and observe the change in the Absolute Cp of the Sensor.

Thanks and regards,

Sobhit