8 Channel Capacitive Touch Sensor with 2 LED Drivers
Datasheet
Appendix A Device Delta
A.1
Delta from CAP1028 to CAP1128
1. Updated circuitry to improve power supply rejection.
2. Updated LED driver duty cycle decode values to have more distribution at lower values - closer to
a logarithmic curve. See Table 5.60, "LED Duty Cycle Decode".
3. Updated bug that breathe periods were not correct above 2.6s. This includes rise / fall time
decodes above 1.5s.
4. Added filtering on RESET pin to prevent errant resets.
5. Updated controls so that the RESET pin assertion places the device into the lowest power state
available and causes an interrupt when released. See Section 4.2, "RESET Pin".
6. Added 1 bit to the LED Off Delay register (see Section 5.38, "LED Off Delay Register") to extend
times from 2s to 5s in 0.5s intervals.
7. Breathe behavior modified. A breathe off delay control was added to the LED Off Delay Register
(see Section 5.38, "LED Off Delay Register") so the LEDs can be configured to remain inactive
between breathes.
8. Added controls for the LED transition effects when linking LEDs to capacitive sensor inputs. See
Section 5.29, "Linked LED Transition Control Register".
9. Added controls to “mirror” the LED duty cycle outputs so that when polarity changes, the LED
brightness levels look right. These bits are automatically set when polarity is set. Added control to
break this auto-set behavior. See Section 5.30, "LED Mirror Control Register".
10. Added Multiple Touch Pattern detection circuitry. See Section 5.15, "Multiple Touch Pattern
Configuration Register".
11. Added General Status register to flag Multiple touches, Multiple Touch Pattern issues and general
touch detections. See Section 5.2, "Status Registers".
12. Added bits 6 and 5 to the Recalibration Configuration register (2Dh - see Section 5.17,
"Recalibration Configuration Register"). These bits control whether the accumulation of
intermediate data and the consecutive negative delta counts counter are cleared when the noise
status bit is set.
13. Added Configuration 2 register for LED linking controls, noise detection controls, and control to
interrupt on press but not on release. Added control to change alert pin polarity. See Section 5.6,
"Configuration Registers".
14. Updated Deep Sleep behavior so that device does not clear DSLEEP bit on received
communications but will wake to communicate.
15. Changed PWM frequency for LED drivers. The PWM frequency was derived from the programmed
breathe period and duty cycle settings and it ranged from ~4Hz to ~8000 Hz. The PWM frequency
has been updated to be a fixed value of ~2000Hz.
16. Register delta:
Table A.1 Register Delta From CAP1028 to CAP1128
ADDRESS
REGISTER DELTA
DELTA
DEFAULT
00h
Page 41
Changed - Main Status
/ Control
added bits 7-6 to control gain
00h
02h
Page 42
new register to store MTP, MULT, LED,
RESET, and general TOUCH bits
New - General Status
00h
SMSC CAP1128
Revision 1.32 (01-05-12)
DATA8S5HEET
SMSC [ SMSC CORPORATION ]
