CAP1106 Datasheet, PDF (23/48 Pages) Microchip Technology – 6 Channel Capacitive Touch Sensor

CAP1106
The Sensitivity Control register controls the sensitivity of a touch detection.
Bits 6-4 DELTA_SENSE[2:0] - Controls the sensitivity of a touch detection. The sensitivity settings act to scale the rel-
ative delta count value higher or lower based on the system parameters. A setting of 000b is the most sensitive while a
setting of 111b is the least sensitive. At the more sensitive settings, touches are detected for a smaller delta capacitance
corresponding to a “lighter” touch. These settings are more sensitive to noise, however, and a noisy environment may
flag more false touches with higher sensitivity levels.
APPLICATION NOTE: A value of 128x is the most sensitive setting available. At the most sensitivity settings, the
MSB of the Delta Count register represents 64 out of ~25,000 which corresponds to a touch
of approximately 0.25% of the base capacitance (or a ΔC of 25fF from a 10pF base
capacitance). Conversely, a value of 1x is the least sensitive setting available. At these
settings, the MSB of the Delta Count register corresponds to a delta count of 8192 counts
out of ~25,000 which corresponds to a touch of approximately 33% of the base capacitance
(or a ΔC of 3.33pF from a 10pF base capacitance).
TABLE 6-8: DELTA_SENSE BIT DECODE
DELTA_SENSE[2:0]
2
1
0
Sensitivity Multiplier
0
0
0
128x (most sensitive)
0
0
1
64x
0
1
0
32x (default)
0
1
1
16x
1
0
0
8x
1
0
1
4x
1
1
0
2x
1
1
1
1x - (least sensitive)
Bits 3 - 0 - BASE_SHIFT[3:0] - Controls the scaling and data presentation of the Base Count registers. The higher the
value of these bits, the larger the range and the lower the resolution of the data presented. The scale factor represents
the multiplier to the bit-weighting presented in these register descriptions.
APPLICATION NOTE: The BASE_SHIFT[3:0] bits normally do not need to be updated. These settings will not affect
touch detection or sensitivity. These bits are sometimes helpful in analyzing the Cap Sensing
board performance and stability.
TABLE 6-9:
3
0
0
0
0
0
0
0
0
1
BASE_SHIFT BIT DECODE
BASE_SHIFT[3:0]
2
1
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
0
0
All others
Data Scaling Factor
0
0
1x
1
2x
0
4x
1
8x
0
16x
1
32x
0
64x
1
128x
0
256x
256x
(default = 1111b)
 2015 Microchip Technology Inc.
DS00001624B-page 23