SNOA993A June   2018  – July 2021 LDC2112 , LDC2114 , LDC3114 , LDC3114-Q1

 

  1.   Trademarks
  2. 1Introduction
  3. 2Scan Rate and Sampling Interval
    1. 2.1 Low Power Mode and Normal Power Mode
    2. 2.2 Button Sequencing and Error Handling
  4. 3Data Polarity and Timeout
    1. 3.1 Button Timeout
  5. 4Internal Algorithms Overview
  6. 5Baseline Tracking
    1. 5.1 Baseline Increment
    2. 5.2 Baseline Tracking Reset
    3. 5.3 Button Actuation Time
    4. 5.4 BTPAUSE
    5. 5.5 Fast Tracking Factor
  7. 6Gain, Hysteresis, and Threshold
    1. 6.1 Threshold and Hysteresis
  8. 7Multi-Button Algorithms
    1. 7.1 Max Win
    2. 7.2 Anti-Common Mode
    3. 7.3 Anti-Twist Factor
    4. 7.4 Anti-Deform Factor
  9. 8Summary
  10. 9Revision History

7.2 Anti-Common Mode

Anti-Common Mode corrects for unintended mechanical deflection which is common to multiple buttons. Figure 7-2 provides a comparison between having Anti-Common enabled vs. disabled for an example stimulus.

GUID-E845D9C6-6A43-4076-B706-E834821B7031-low.gifFigure 7-2 Anti-Common Functionality

Buttons can be included in the Anti-Common group by setting the corresponding ANTICOMx field to 1. The default setting for the ANTICOMx field is 0, which disables Anti-Common for corresponding channel. The pseudo-code for this algorithm is equivalent to:

ACM_offset = (∑net[channel] )/num_acm_chan

For each (channel with enabled ACM)

net[channel] = net[channel] – ACM_offset

Next channel

Note that the Net output value readback from the LDC211x is changed by the use of this algorithm.