MPR121_10 FREESCALE [Freescale Semiconductor, Inc], MPR121_10 Datasheet - Page 28

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

MPR121
28
FILTER DELAY LIMIT (FDL)
data or touched data. When the data changes between these conditions, the current filter process is cancelled and all filter
counters return to zero.
touch will also change the operation of the system. The touch generation process is described in the application note AN3892.
The falling data system is enabled any time the 2
any time the 2
changing between the three states mentioned above.
Case 1
regulates this case by allowing any data that is less than two times the MHD to pass the filter. Thus, if the baseline is 700 and
the data is 701 with a MHD of one, then the baseline filter would increase to equal the data for the next cycle.
Table 25. Filter Delay Limit Register Field Descriptions
Additionally there are different conditions in the system that affects how these registers operate. These are rising data, falling
The operation of the filter is in the relationship between the 2
Small incremental changes to the system represent long term slow (environmental) changes in the system. The MHD setting
Field
nd
FDL
7:0
Reset:
filter data is greater than the baseline filter data. The following cases describe the baseline system when it is not
W
R
7
0
Filter Delay Limit – The Filter Delay Limit determines the rate of operation of the
filter. A larger number makes it operate slower.
00000000 Encoding 0 – Sets the Filter Delay Limit to 1
00000001 Encoding 1 – Sets the Filter Delay Limit to 2
~
11111111 Encoding 255 – Sets the Filter Delay Limit to 255
MHD = 1
= Unimplemented
6
0
Figure 27. Filter Delay Limit Register
nd
Figure 28. Max Half Delta
filter data is less than the baseline filter data. The rising data system is enabled
5
0
4
0
nd
filter data and the baseline filter value. The occurrence of a
FDL
Description
3
0
2
0
Baseline
Data
1
0
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0
0
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