MPR121_10 FREESCALE [Freescale Semiconductor, Inc], MPR121_10 Datasheet - Page 15

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

Sensors
Freescale Semiconductor
FILTER CONFIGURATION REGISTER
electrodes can also be independently configured.
ELECTRODE CHARGE CURRENT REGISTER
The SFI, ESI and FFI are described in AN3890. In addition to these global (same for all electrodes) settings, the MPR121
Table 10. Filter Configuration Register Field Descriptions
Table 11. Electrode Charge Current Register Field Descriptions
Reset:
Reset:
Field
Field
CDC
CDT
ESI
SFI
7:5
4:3
2:0
5:0
W
W
R
R
7
0
7
0
0
= Unimplemented
= Unimplemented
Charge Discharge Time – The Charge Discharge Time field selects the amount of
time an electrode charges and discharges.
000 Encoding 0 – Invalid
001 Encoding 1 – Time is set to 0.5 μs
010 Encoding 2 – Time is set to 1 μs
~
111 Encoding 7 – Time is set to 32 μs.
Second Filter Iterations – The Second Filter Iterations field selects the number of
samples taken for the second level filter.
00 Encoding 0 – Number of samples is set to 4
01 Encoding 1 – Number of samples is set to 6
10 Encoding 2 – Number of samples is set to 10
11 Encoding 3 – Number of samples is set to 18
Electrode Sample Interval – The Electrode Sample Interval field selects the period
between samples used for the second level of filtering.
000 Encoding 0 – Period set to 1 ms
001 Encoding 1 – Period set to 2 ms
~
111 Encoding 7 – Period set to 128 ms
Electrode # Charge Discharge Current – The Charge Discharge Current field
selects the supply current to be used when charging and discharging an electrode.
000000 Encoding 0 – Disables Electrode Charging
000001 Encoding 1 – Sets the current to 1μA
~
111111 Encoding 63 – Sets the current to 63 μA
CDT
Figure 10. Electrode Charge Current Register
6
0
6
0
0
Figure 9. Filter Configuration Register
5
0
5
0
4
0
4
0
SFI
Description
Description
3
0
3
0
CDC
2
0
2
0
ESI
1
0
1
0
0
0
0
0
MPR121
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