NXP Semiconductors MKW01Z128, Reference Manual, Page: 832 / 884

current source takes more time for charge and discharge, which is useful to detect high-
accuracy change. The higher current source takes less time, which can be used to charge
a big electrode by less power consumption.
TSI_GENCS[CURSW] allows the current source to swap, so that the reference oscillator
and electrode oscillator use the opposite current sources. When TSI_GENCS[CURSW] is
set and the current sources are swapped, TSI_GENCS[EXTCHRG] and
TSI_GENCS[REFCHRG] still control the corresponding current sources, that is,
TSI_GENCS[EXTCHRG] controls the reference oscillator current and
TSI_GENCS[REFCHRG] controls the electrode oscillator current.
35.4.9 End of scan
As a scan starts, [SCNIP] bit is set to indicate scan is in progress. When the scan
completes, the [EOSF] bit is set. Before clearing the [EOSF] bit, the value in
TSI_DATA[TSICNT] must be read. If the TSI_GENCS[TSIIEN] and
TSI_GENCS[ESOR] are set andTSI_GENCS[DMAEN]is not set, an interrupt is
submitted to CPU for post-processing immediately. The interrupt is also optional to wake
MCU to execute ISR if it is in low power mode. When DMA function is enabled by
setting TSI_GENCS[TSIIEN] and TSI_GENCS[ESOR], as soon as scan completes, a
DMA transfer request is asserted to DMA controller for data movement, generally, DMA
engine will fetch TSI conversion result from TSI_DATA register,store it to other memory
space and then refresh the TSI scan channel index(TSI_DATA[TSICH]) for next loop.
When DMA transfer is done, TSI_GENCS[EOSF] is cleared automatically.
35.4.10 Out-of-range interrupt
If enabled, TSI will scan the electrode specified by TSI_DATA[TSICH] as soon as the
trigger arrives. The TSI_GENCS[OUTRGF] flag generates a TSI interrupt request if the
TSI_GENCS[TSIIE] bit is set and GENCS[ESOR] bit is cleared. With this configuration,
after the end-of-electrode scan, the electrode capacitance will be converted and stored to
the result register TSI_DATA[TSICNT], the out-of-range interrupt is only requested if
there is a considerable capacitance change defined by the TSI_TSHD. For instance, if in
low power mode the electrode capacitance does not vary, the out-of-range interrupt does
not interrupt the CPU. This interrupt will not happen in noise detection mode. It is worthy
to note that when the counter value reaches 0xFFFF is treated as an extreme case the out-
of-range will not happen. Also in noise detection mode, the out-of-range will not assert
either.
Chapter 35 Touch Sensing Input (TSI)
MKW01Z128 MCU Reference Manual, Rev. 3, 04/2016
Freescale Semiconductor, Inc. 701