NXP Semiconductors MKW01Z128, Reference Manual, Page: 831 / 884

counter accumulates all scan results until the NSCN time scan completes, and users can
read TSI_DATA[TSICNT] to get this accumulation. When DMA transfer is enabled, the
counter values can also be read out by DMA engine.
35.4.6 Clock setting
TSI is built with dual oscillator architecture. In normal sensing application, the reference
oscillator clock is the only clock source for operations. The reference clock is used to
measure the electrode oscillator by ticking a 16-bit counter. The reference oscillator
frequency depends on the current source setting. Please refer to the
Current source for
more details.
The output of electrode oscillator has several prescalers up to 128 indicated by
TSI_GENCS[PS]. This allows a flexible counter configuration for different electrode
oscillator frequency.
35.4.7 Reference voltage
The TSI module offers a internal reference voltage for both electrode oscillator and
reference oscillator. The internal reference voltage can work in low power modes even
when the MCU regulator is partially powered down, which is ideally for low-power touch
detection.
The charge and discharge difference voltage is configurable upon the setting of
TSI_GENCS[DVOLT]. The following table shows the all the delta voltage
configurations.
NOTE
This table doesn't apply to noise mode, see noise mode sections
for its configuration.
35.4.8 Current source
The TSI module supports eight different current source power to increment from 500 nA
to 64 µA. TSI_GENCS[EXTCHRG] determines the current of electrode oscillator that
charges and discharges external electrodes. The TSI_GENCS[REFCHRG] determines the
current of reference oscillator on which the internal reference clock depends. The lower
Functional description
MKW01Z128 MCU Reference Manual, Rev. 3, 04/2016
700 Freescale Semiconductor, Inc.