SNOA993A June 2018 – July 2021 LDC2112 , LDC2114 , LDC3114 , LDC3114-Q1
4 Internal Algorithms Overview
The LDC211x and LDC3114 devices take the output measurements for each channel and apply a sequence of several algorithms to the conversion results. Some of the algorithms are optional, and some can be configured per-channel. Table 4-1 below lists the internal algorithms and the configuration options applicable for each algorithm.
Table 4-1 LDC211x and LDC3114 Internal Algorithms
| Algorithm | Always Applied or Optional? | Configuration | Per Channel | Functionality |
|---|---|---|---|---|
| Data Polarity | Always | DPOLx | Y | Select Inductive or Capacitive sensing operation |
| Baseline Tracking | Always | NPBI/LPBI | N | Compensates for environmental shifts in inductance and capacitance. |
| Fast Tracking | Optional | FTF | Y | Provides faster recovery for negative swings in output code values. |
| Gain | Always | GAINx | Y | Adjusts sensitivity of channel. Scales between 1x and 232x in 64 settings; average step delta is 9%. |
| Threshold Compare | Always | N/A | N | Centered at 128. Effectively adjusted by use of GAINx. |
| Hysteresis | Always | HYST | N | Sets button actuation or deactivation thresholds. Centered at fixed Threshold Compare level of 128. Adjustable from 0 to 60 in steps of 4. |
| Baseline Tracking Pause | Optional | BTPAUSEx | Y | Disables Baseline Tracking when OUTx value exceeds THRESHOLD+HYSTERSIS. Baseline Tracking is disabled in raw data access mode of LDC3114. |
| Max Win | Optional | MAXWINx | Y | Compares OUTx across selected channels and deasserts OUTx signal for all but the highest value channel. |
| Anti-Common | Optional | ANTICOMx | Y | Suppress common-mode signal present on multiple channels which are due to mechanical cross-talk. |
| Anti-Deform | Optional | ANTIDFORMx | Y | Compensate the baseline tracking for non-ideal recovery from mechanical stresses. |
| Anti-Twist | Optional | ANTITWIST | N | Suppress inverse signals present on multiple channels which are due to mechanical cross-talk. |
The various algorithms are applied in the sequence shown in Figure 4-1. For algorithms which are optional, if the algorithm is not enabled, then the channel data is not modified in by block.
Figure 4-1 Algorithm Sequence