CAP1298 Datasheet, PDF (47/68 Pages) Microchip Technology – 8-Channel Capacitive Touch Sensor Controller with Proximity Detection & Signal Guard

CAP1298
Bit 7 - AVG_SUM - Determines whether the sensor inputs enabled in Standby will average the programmed number of
samples or whether they will accumulate for the programmed number of samples.
• ‘0’ - (default) - The Standby enabled sensor input delta count values will be based on the average of the pro-
grammed number of samples when compared against the threshold.
• ‘1’ - The Standby enabled sensor input delta count values will be based on the summation of the programmed
number of samples when compared against the threshold. Caution should be used with this setting as a touch
may overflow the delta count registers and may result in false readings.
Bits 6 - 4 - STBY_AVG[2:0] - Determines the number of samples that are taken for all Standby enabled channels during
the sensing cycle as shown in Table 5-6. All samples are taken consecutively on the same channel before the next chan-
nel is sampled and the result is averaged over the number of samples measured before updating the measured results.
TABLE 5-6: STBY_AVG BIT DECODE
STBY_AVG[2:0]
2
1
0
0
0
0
0
1
0
1
1
0
1
0
1
1
1
1
Number Of Samples Taken Per
Measurement
0
0
1
1
2
0
4
1
8 (default)
0
16
1
32
0
64
1
128
Bit 3 - 2 - STBY_SAMP_TIME[1:0] - Determines the time to take a single sample for sensor inputs enabled in Standby
as shown in Table 5-7.
TABLE 5-7: STBY_SAMP_TIME BIT DECODE
STBY_SAMP_TIME[1:0]
1
0
0
0
0
1
1
0
1
1
Sampling Time
320us
640us
1.28ms (default)
2.56ms
Bits 1 - 0 - STBY_CY_TIME[2:0] - Determines the desired sensing cycle time for sensor inputs enabled during Standby,
as shown in Table 5-8. This control is also used to determine programmed cycle time in the Combo state (see Section
4.3.1.3, "Combo State Sensing Settings"). All enabled channels are sampled at the beginning of the sensing cycle. If
additional time is remaining, the device is placed into a lower power state for the remainder of the sensing cycle.
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DS00001571B-page 47