Datasheet
Table Of Contents
- Proximity Capacitive Touch Sensor Controller
- 1 Pin Descriptions
- 2 Schematic Drawings and Implementation
- 3 Device Operation Overview
- 4 Electrical Characteristics
- 5 Register Operation Descriptions
- 5.1 Register Read/Write Operations and Measurement Run/Stop Mode
- 5.2 Touch Status Registers (0x00~0x01)
- 5.3 Electrode Filtered Data Register (0x04~0x1D)
- 5.4 Baseline Value Register (0x1E~0x2A)
- 5.5 Baseline Filtering Control Register (0x2B~0x40)
- 5.6 Touch / Release Threshold (0x41~0x5A)
- 5.7 Debounce Register (0x5B)
- 5.8 Filter and Global CDC CDT Configuration (0x5C, 0x5D)
- 5.9 Electrode Charge Current Register (0x5F~0x6B)
- 5.10 Electrode Charge Time Register (0x6C~0x72)
- 5.11 Electrode Configuration Register (ECR, 0x5E)
- 5.12 Out-Of-Range Status Registers (0x02, 0x03)
- 5.13 Soft Rest Register (0x80)
- 5.14 GPIO Registers (0x73~0x7A)
- 6 MPR121 Serial Communication
- Disclaimer
MPR121
Sensors
14 Freescale Semiconductor, Inc.
5.8 Filter and Global CDC CDT Configuration (0x5C, 0x5D)
Filter/Global CDC Configuration Register (0x5C)
Bit D7 D6 D5 D4 D3 D2 D1 D0
Read
FFI CDC
Write
Filter/Global CDT Configuration Register (0x5D)
Bit D7 D6 D5 D4 D3 D2 D1 D0
Read
CDT SFI ESI
Write
Table 8. Bit Descriptions
Field Description
FFI
First Filter Iterations - The first filter iterations field selects the number of samples taken as
input to the first level of filtering.
00 Encoding 0 - Sets samples taken to 6 (Default)
01 Encoding 1 - Sets samples taken to 10
10 Encoding 2 - Sets samples taken to 18
11 Encoding 3 - Sets samples taken to 34
CDC
Charge Discharge Current - Selects the global value of charge discharge current applied to
electrode. The maximum is 63 μA, 1 μA step.
000000 Encoding 0 - Disable Electrode Charging
000001 Encoding 1 - Sets the current to 1 μA
~
010000 Encoding 16 - Sets the current to 16 μA (Default)
~
111111 Encoding 63 - Sets the current to 63 μA
CDT
Charge Discharge Time - Selects the global value of charge time applied to electrode.
The maximum is 32 μs, programmable as 2 ^(n-2) μs.
000 Encoding 0 - Disables Electrode Charging
001 Encoding 1 - Time is set to 0.5 μs (Default)
010 Encoding 2 - Time is set to 1 μs
~
111 Encoding 7 - Time is set to 32 μs
SFI
Second Filter Iterations - Selects the number of samples taken for the second level filter
00 Encoding 0 - Number of samples is set to 4 (Default)
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
ESI
Electrode Sample Interval - Selects the period between samples used for the second level
of filtering. The maximum is 128ms, Programmable to 2^n ms
000 Encoding 0 - Period set to 1 ms
001 Encoding 1 - Period set to 2 ms
~
100 Encoding 4 - Period set to 16 ms (Default)
~
111 Encoding 7 - Period set to 128 ms