CAP1214 Datasheet, PDF (89/107 Pages) SMSC Corporation – Multiple Channel Capacitive Touch Sensor and LED Driver

LEDX_CTL
[1:0]
1
0
1
0
1
1
Multiple Channel Capacitive Touch Sensor and LED Driver
Table 6.73 LEDx_CTL Bit Decode (continued)
Datasheet
OPERATION
Pulse 2
Breathe
DESCRIPTION
START
TRIGGER
STOP
TRIGGER
The LED will “Pulse” when the start trigger
is detected. When the stop trigger is
detected, it will “Pulse” a programmable
number of times then return to its minimum
brightness.
The LED will breathe. It will be driven with
a duty cycle that ramps up from the
programmed minimum duty cycle (default
0%) to the programmed maximum duty
cycle (default 100%) and then back down.
Each ramp takes up 50% of the
programmed period. The total period of
each “breath” is determined by the LED
Breathe Period controls - see Section 6.54.
Touch Detected
or LED Output
Control bit set
Touch Detected
or LED Output
Control bit set
Release
Detected or
LED Output
Control bit
cleared
Release
Detected or
LED Control
Output bit
cleared
APPLICATION NOTE: The PWM frequency is determined based on the selected LED behavior, the programmed
breathe period, and the programmed min and max duty cycles. For the Direct behavior
mode, the PWM frequency is calculated based on the programmed Rise and Fall times. If
these are set at 0, the maximum PWM frequency will be used based on the programmed
duty cycle settings.
6.52 LED Pulse 1 Period Register
ADDR R/W
84h
R/W
REGISTER
LED Pulse 1
Period
Table 6.74 LED Pulse 1 Period Register
B7
ST_
TRIG
B6
B5
B4
B3
B2
P1_ P1_ P1_ P1_ P1_
PER6 PER5 PER4 PER3 PER2
B1
P1_
PER1
B0
P1_
PER0
DEFAULT
20h
The LED Pulse 1 Period Register determines the overall period of a pulse operation as determined by
the LED_CTL registers (see Table 6.73 - setting 01b). Each LSB represents 32ms so that a setting of
20h (32d) would represent a period of 1024ms (32ms x 32 = 1024ms). The total range is from 32ms
to 4.06 seconds as shown in Table 6.75.
The number of pulses is programmable as determined by the PULSE1_CNT bits (see Section 6.55).
Bit 7 - ST_TRIG - Determines the start trigger for the LED Pulse behavior.
„ ‘0’ (default) - The LED will Pulse when a touch is detected or the drive bit is set.
„ ‘1’ - The LED will Pulse when a release is detected or the drive bit is cleared.
The Pulse 1 operation is shown in Figure 6.1 (non-inverted polarity LEDx_POL = 1) and Figure 6.2
(inverted polarity LEDx_POL = 0).
SMSC CAP1214
89
DATASHEET
Revision 1.0 (08-30-10)