MPR121_10 FREESCALE [Freescale Semiconductor, Inc], MPR121_10 Datasheet - Page 29

• Manufacturer Part Number: MPR121_10
• Description: Proximity Capactive touch Senosr controller
• Manufacturer: FREESCALE [Freescale Semiconductor, Inc]

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Case 2
Any data outside the MHD is rejected by the filter however sequential values that fall into this category are counted and if enough
sequential data exists then the baseline will be adjusted.
is reached, the baseline is incremented by the NHD.
Case 3
the filter counters are reset, thus the fact that the data is oscillating around the baseline means that the noise is rejected and the
baseline will not vary.
Case 4
system. This is done by taking an average of the specified number of values before running them through the baseline filter.
Changes that are larger than double the MHD are regarded as noise and accounted for by the values of the NHD and NCL.
In this case, the NCL regulates how many sequential data points must be seen before the data is changed. When the count
When the data is inconsistent but greater than double than MHD the baseline will not vary. Each time a transition takes place,
Low frequency changes to the data can trick the filter in some instances. The FDL is also available to slow down the overall
MHD = 1
NCL = 3
NHD = 1
MHD = 1
NCL = 3
NHD = 1
2 < NCL
3 counts
2 < NCL
3 counts
1 < NCL
Figure 29.
Figure 30.
Figure 31.
1 < NCL
NHD added to
baseline
Case 1 comes
into effect
Data
Averaged
Data
Baseline
Data
Baseline
Data
MPR121
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