CAP1214 datasheet(29/107 Pages) MICROCHIP

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Multiple Channel Capacitive Touch Sensor and LED Driver

Datasheet

SMSC CAP1214

Revision 1.0 (08-30-10)

DATASHEET

Based on the multiple button touch settings (see Section 6.23), both CS8 and CS14 may detect a

touch simultaneously and both UP and DOWN status bits may be set.

5.7

FEEDBACK Pin

The FEEDBACK pin can drive an external device (such as a piezo transducer) to generate feedback

(sound or vibration) to the final application user. The FEEDBACK pin can be driven when a touch is

detected (see Section 6.41, "Feedback Channel Configuration Registers"), or it can be driven by the

host (see Section 6.42, "Feedback One-Shot Register"). Duration and frequency of the output are

programmable (see Section 6.40, "Feedback Configuration Register").

When activated, the FEEDBACK pin drives a 50% duty cycle signal at the programmed frequency for

the programmed duration.

5.8

ALERT Pin

The ALERT pin is an active high output that asserts when an interrupt event is detected. It is also used

to wake the device from Deep Sleep state.

Whenever an interrupt is generated, the INT bit (see Section 6.1) is set. The ALERT pin is cleared

when INT bit is cleared by the user. Additionally, if no press is detected, the status bits are cleared

when the INT bit is cleared.

5.8.1

Button Interrupt Behavior

For non-grouped buttons, an interrupt is generated when a touch is detected. If the repeat rate is

enabled (see Section 6.14), then, so long as the touch is held, another interrupt will be generated

based on the programmed repeat rate (see Figure 5.2) and upon release. If repeat rate is not enabled,

an interrupt is generated when a touch is detected and optionally, can be generated at release (see

Section 6.33 and Figure 5.3).

Figure 5.2 Button Interrupt Behavior - Repeat Rate Enabled

Touch Detected

ALERT Pin /

INT bit

Button Status

SMBus Write to

INT bit

Polling Cycle

(35ms)

Button Repeat Rate

(175ms)

Optional

Interrupt on

Release

Interrupt on

Touch

Button Repeat Rate

(175ms)

Button Repeat Rate

(175ms)

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