there is a considerable capacitance change defined by the TSI_TSHD. For instance, if inlow power mode the electrode capacitance does not vary, the out-of-range interrupt doesnot interrupt the CPU. This interrupt will not happen in noise detection mode. It is worthyto 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 asserteither.42.4.11 Wake up MCU from low power modesIn 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 endof scan or out of range interrupt, that is, if TSI_GENCS[ESOR] is set, end of scaninterrupt is selected and otherwise, out of range is selected.42.4.12 DMA function supportTransmit by DMA is supported only when TSI_DATA[DMAEN] is set. A DMA transferrequest is asserted when all of TSI_GENCS[EOSF], TSI_GENCS[ESOR] andTSI_GENCS[TSIIE] are set. Then the on-chip DMA controller detects this request andtransfers data between memory space and TSI register space. After the data tranfer, DMADONE is asserted to clear TSI_GENCS[EOSF] automatically. This function is normallyused by DMA controller to get the conversion result from TSI_DATA[TSICNT] upon aend-of-scan event and then refresh the channel index(TSI_DATA[TSICH]) for nexttrigger. DMA function is not available when MCU is in stop modes.42.4.13 Noise detection modeThe noise detection mode change the circuit configuration as shown in the followingfigure. With this configuration, it is possible to detect touch with high levels of EMCnoise present. To enter the test mode, see TSIx_GENCS[MODE] register field.In noise detection mode the reference oscillator has the same configuration except theoutput 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 circuitimplements an RF amplitude detection. The thrshold for this amplitude detection is set byDVOLT register bits.Also the external voltage is biased by vmid voltage with a Rs series resistance.Functional descriptionKL25 Sub-Family Reference Manual, Rev. 3, September 2012800 Freescale Semiconductor, Inc.
