Data Sheet

MPR121 Sensor
15 Freescale Semiconductor
11. Electrode Configuration Register (ECR, 0x5E)
Bit
D7
D6
D5
D4
D3
D2
D1
D0
Read
CL[1:0]
ELEPROX[1:0]
ELE[3:0]
Write
This register selects measurement electrodes and proximity detection electrode configurations, and controls MPR121 in Run
Mode or Stop Mode. MPR121 reset default is in Stop Mode without any capacitance measurement.
To start capacitance measurement and touch detection, set into Run Mode by selecting the sensing inputs to be enabled.
MPR121 can be set into Stop Mode by writing 2bXX000000 to ECR at any time.
CL: Calibration Lock bit. The CL bits controls the Baseline Value Register update. Typically CL=2b10 is used so the baseline
value can be initialized at the beginning stage with a value close to the immediate data instead of starting from zero. Since the
3
rd
level filter has a big time constant, starting from zero may cause a long time of no response with touch.
CL[1:0]
Description
00
Baseline tracking enable (Default). The baseline values updates every {ESI x SFI} period by
MPR121 per baseline filter operation. The initial value is?????
01
Calibration lock. Baseline tracking disabled. Baseline values are unchanged by MPR121.
10
Baseline tracking and initialize enable. At the first {ESI x SFI}, MPR121 copy 5MSBs of the
2
nd
filter output to 10bit baseline value (5LSBs become zero). Subsequent update is per
nominal baseline filter operation.
11
Baseline tracking and initialize enable. At the first {ESI x SFI}, MPR121 copy the 2
nd
filter
output to 10bit baseline value. Subsequent update is per nominal baseline filter operation.
ELE[3:0]
Description
0000
Electrode touch detection disabled (Default)
0001
Run Mode with ELE0 measurement enabled.
0010
Run Mode with ELE0~1 measurement enabled.
0011
Run Mode with ELE0~2 measurement enabled.
0100
Run Mode with ELE0~3 measurement enabled.
0101
Run Mode with ELE0~4 measurement enabled.
0110
Run Mode with ELE0~5 measurement enabled.
0111
Run Mode with ELE0~6 measurement enabled.
1000
Run Mode with ELE0~7 measurement enabled.
1001
Run Mode with ELE0~8 measurement enabled.
1010
Run Mode with ELE0~9 measurement enabled.
1011
Run Mode with ELE0~10 measurement enabled.
11xx
Run Mode with ELE0~11 measurement enabled.
ELEPROX[1:0]
Description
00
Proximity detection disabled( Default)
01
Run Mode with ELE0~1 for proximity detection enabled.
10
Run Mode with ELE0~3 for proximity detection enabled.
11
Run Mode with ELE0~11for proximity detection enabled.
When both ELEPROX and ELE are none zero, proximity detection measures first then measures electrode(s). When both
ELEPROX and ELE are cleared, MPR121 will be back to Stop Mode.
ELE: When ELECON ≠ 0, electrode touch detection with specific electrodes is enabled
ELEPROX: When ELEPROXCON≠ 0, proximity detection with specific electrodes combination is enabled