NXP Semiconductors MKL25Z128VLK4 - Wake up MCU from Low Power Modes

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.
42.4.11 Wake up MCU from low power modes
In low power modes, once enabled by TSI_GENCS[STPE] and TSI_GENCS[TSIIE],
TSI can bring MCU out of its low power modes(STOP, VLPS, VLLS,etc) by either end
of scan or out of range interrupt, that is, if TSI_GENCS[ESOR] is set, end of scan
interrupt is selected and otherwise, out of range is selected.
42.4.12 DMA function support
Transmit by DMA is supported only when TSI_DATA[DMAEN] is set. A DMA transfer
request is asserted when all of TSI_GENCS[EOSF], TSI_GENCS[ESOR] and
TSI_GENCS[TSIIE] are set. Then the on-chip DMA controller detects this request and
transfers data between memory space and TSI register space. After the data tranfer, DMA
DONE is asserted to clear TSI_GENCS[EOSF] automatically. This function is normally
used by DMA controller to get the conversion result from TSI_DATA[TSICNT] upon a
end-of-scan event and then refresh the channel index(TSI_DATA[TSICH]) for next
trigger. DMA function is not available when MCU is in stop modes.
42.4.13 Noise detection mode
The noise detection mode change the circuit configuration as shown in the following
figure. With this configuration, it is possible to detect touch with high levels of EMC
noise present. To enter the test mode, see TSIx_GENCS[MODE] register field.
In noise detection mode the reference oscillator has the same configuration except the
output goes to Counter2 and this counter will have the it's maximum count set by NSCN.
2^(PS). This means this oscillator will setup the noise detection mode sense duration.
The blocks of external oscillator is changed and instead of an oscillator the circuit
implements an RF amplitude detection. The thrshold for this amplitude detection is set by
DVOLT register bits.
Also the external voltage is biased by vmid voltage with a Rs series resistance.
Functional description
KL25 Sub-Family Reference Manual, Rev. 3, September 2012
800 Freescale Semiconductor, Inc.