8 Channel Capacitive Touch Sensor with 8 LED Drivers
Datasheet
2. If the repeat rate is enabled (see Section 5.6), then, so long as the touch is held, another interrupt
will be generated based on the programmed repeat rate (see Figure 4.2).
When the repeat rate is enabled, the device uses an additional control called MPRESS that determines
whether a touch is flagged as a simple “touch” or a “press and hold”. The MPRESS[3:0] bits set a
minimum press timer. When the button is touched the timer begins. If the sensor is released before
the minimum press timer expires, then it is flagged as a touch and an interrupt is generated upon the
release. If the sensor detects a touch for longer than this timer value, then it is flagged as a “press
and hold” event. So long as the touch is held, interrupts will be generated at the programmed repeat
rate and upon a release.
Polling Cycle
(35ms)
Interrupt on
Touch
Interrupt on
Release
Button Repeat Rate
(175ms)
Button Repeat Rate
(175ms)
Button Repeat Rate
(175ms)
Touch Detected
ALERT Pin / INT bit
Button Status
SMBus Write to INT bit
Figure 4.2 Sensor Interrupt Behavior - Repeat Rate Enabled
APPLICATION NOTE: The host may need to poll the device twice to determine that a release has been detected.
Polling Cycle
(35ms)
Interrupt on
Touch
Interrupt on
Release
Touch Detected
ALERT Pin /
INT bit
Button Status
SMBus Write to
INT bit
Figure 4.3 Sensor Interrupt Behavior - No Repeat Rate Enabled
SMSC CAP1088
Revision 1.1 (08-05-09)
DATA3S1HEET
SMSC [ SMSC CORPORATION ]
