MPR121_10 FREESCALE [Freescale Semiconductor, Inc], MPR121_10 Datasheet - Page 40

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

MPR121
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electrode. Writing to Baseline Value Register updates the 8 MSBs of baseline value and clears the 2 LSBs to zero. The Baseline
Value Registers can only be written when in Shutdown Mode, but the current values may be read at any time.
Table 36. Eleprox Baseline Value Register 0x2A (Reset Default: 0x00)
3.0
changes as a result of internal detection algorithm using the proximity raw data with the proximity baseline value and proximity
touch/release threshold setting. When ELE[12] is set, the proximity is deemed as detected, and undetected when ELE[12] is 0.
Table 37. Status Register 0x00, 0x01 (Reset Default: 0x00)
immediately change if the Debounce Register is non zero. This Debounce Register is globally effective to prevent possible flick
noise for both touch and proximity sensing. The value in the Debounce Register determines how many numbers of sample inter-
vals are needed to pass at the touch/release threshold before the status bit is finally changed.
On ELEPROX status bit change, the interrupt pin will be asserted.
4.0
setting registers. The programmable threshold setting range is 0~63 count, representing the delta change below the baseline
value when touched or released. The Threshold should be set according to the system SNR requirement and also provide ade-
quate headroom for mass production variation. For normal application, set Touch Threshold slightly larger than Release Thresh-
old so that there is no flick detection.
Example: Touch Threshold = 0x08, Release Threshold = 0x05.
Table 38. Debounce Register 0x5B (Reset Default: 0x00)
Table 39. Eleprox Touch Threshold Register 0x59 (Reset Default: 0x00)
Table 40. Eleprox Release Threshold Register 0x5A (Reset Default: 0x00)
Eleprox Baseline Value Register (0x2A) contains the 8 MSBs of the 10-bit baseline value for the 13
MPR121 provides a single proximity sensing status bit (ELE[12] in table below) in the Touch Status Register. This status bit
The update rate of this status bit will be determined by sampling rate and detection debounce setting. The status bit will not
Similar to the touch/release threshold for touch detection, the proximity detection also has a pair of touch/release threshold
0x2A
0x00
0x01
0x5B
0x5A
0x59
Proximity Sensing Status Indication
Proximity Detection Touch/Release Threshold
ELE[7]
OVCF
Bit7
Bit7
Bit7
Bit7
Bit7
Bit7
D9
D7
D7
X
ELE[6]
DR[2]
Bit6
Bit6
Bit6
Bit6
Bit6
Bit6
D8
D6
D6
0
ELE[5]
Bit5
Bit5
DR[1]
Bit5
Bit5
Bit5
Bit5
D7
D5
D5
0
ELE[12]
ELE[4]
DR[0]
Bit4
Bit4
Bit4
Bit4
Bit4
Bit4
D6
D4
D4
ELE[11]
ELE[3]
Bit3
Bit3
Bit3
Bit3
Bit3
Bit3
D5
D3
D3
X
ELE[10]
ELE[2]
DT[2]
Bit2
Bit2
Bit2
Bit2
D4
D2
D2
Bit2
Bit2
Freescale Semiconductor
th
ELE[1]
ELE[9]
DT[1]
Bit1
Bit1
Bit1
Bit1
Proximity Detection
D1
D1
D3
Bit1
Bit1
ELE[0]
ELE[8]
DT[0]
Bit0
Bit0
Bit0
Bit0
Sensors
Bit0
Bit0
D0
D0
D2