Author: ShanmathiN_06 Version: *A
Translation - Japanese: 温度、湿度、およびその他の緩やかな環境変化に対応した設計のためのCapSenseパラメータの設定- KBA225128- Community Translated (JA)
How can IDAC calibration percentage, sense clock source, sense clock frequency, and modulator clock frequency for CapSense® designs be set with gradual environmental variations?
When the CapSense sensors are subjected to gradual environmental variations, the baseline may track the raw counts gradually due to changes in temperature, humidity, or other environmental conditions.
Typically, auto calibration will calibrate the IDAC such that raw counts are calibrated to 85% and 40% of the maximum raw counts for CSD and CSX respectively.
However, gradual environmental variations could result in the following undesirable scenarios:
For example, in CSD-based designs, baseline (85% of maximum raw counts) will gradually follow the raw counts and may reach even 95% of maximum raw counts and eventually get saturated. Similarly, in CSX-based designs, baseline (40% of maximum raw counts) will gradually follow the raw counts and may reach even 5% of maximum raw counts and eventually get saturated. To avoid the raw counts from increasing gradually and saturating to maximum raw counts, do not calibrate the raw counts to the typical calibration percentage. Instead, calibrate the raw counts to a specific percentage depending on the type of CapSense sensors to allow room for changes in baseline due to gradual temperature and humidity variations.
To change the calibration percentage, disable IDAC auto-calibration and set IDAC codes manually or enable IDAC auto-calibration and use the CapSense_CSDCalibrateWidget () API to set the raw count calibration to a lesser and higher percentage for CSD and CSX-based CapSense designs, respectively.
Follow these steps to reduce the width of flat spots:
Thus, the flat spots can be reduced and the undesirable consequences of gradual environmental variations can be overcome.