CAP1114 datasheet(72/102 Pages) MICROCHIP

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Multiple Channel Capacitive Touch Sensor and LED Driver

Datasheet

Revision 1.1 (02-04-11)

SMSC CAP1114

DATASHEET

6.35

Proximity Control Register

The Proximity Control Register controls sensitivity settings for CS1.

Bit 7 - CS1_PROX - Determines the functionality of the CS1 channel.

‘0’ (default) - The CS1 channel is not measuring proximity. It will use the standard button queue

and data sensitivity controls. The Averaging will be set to a value of ‘1’. Writing to the

PROX_AVG[2:0] bits will change the averaging applied to CS1 (and only CS1).

‘1’ - The CS1 channel is measuring proximity. It will not use the queue. In addition, the CS1 channel

will not use the DELTA_SHIFT[2:0] sensitivity settings and will instead use the

PROX_D_SHIFT[2:0] settings. In proximity mode, the signal is boosted by 8X to detect very small

capacitance changes.

Bit 6 - PROX_SUM - Determines whether the CS1 channel averaging will perform an average or

calculate the sum of the measured channel when comparing the delta count against the threshold.

‘0’ (default) - When configured to detect proximity, the CS1 channel delta counts will be the

average.

‘1’ - When configured to detect proximity, the CS1 channel will sum the results of the averages

rather than report the true average. This value will be compared against the threshold normally.

Note that this mode is intended for very small signal detection. Because the delta count is the

summation of several consecutive measurements, it may become very large. Adjustments to the

sensitivity and threshold values will be required to maintain proper operation.

Bits 5 - 3 - PROX_AVG[1:0] - Determines the averaging value used when CS1 is set to detect

proximity. When averaging is enabled (i.e. not set at a value of ‘1’), the CS1 sensor will be sampled

the average number of times consecutively during the same polling cycle. The delta counts are

summed and then divided by the number of averages to get an average delta which is compared

against the threshold normally.

This will increase the time of the polling cycle linearly with the number of averages taken. As the polling

cycle time is used to set the update rate, repeat rate, and recalibration times, these will likewise

increase. See Table 6.53.

Note 6.4

The Polling time increase is based on the default sampling time as determined by the

Sampling Configuration register (see Section 6.37).

Table 6.52 Proximity Control Register

ADDR

R/W

DEFAULT

42h

R/W

Proximity

Control

CS1_

PROX

PROX_

SUM

PROX_AVG

[1:0]

PROX_D_SENSE[2:0]

02h

Table 6.53 PROX_AVG Bit Decode

PROX_AVG[1:0]

NUMBER OF DIGITAL

AVERAGES

POLLING CYCLE TIME

INCREASE (SEE Note 6.4)

16 (default)

+38.4ms

+79.36ms

+161.28ms

128

+325.12ms

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