NXP Semiconductors K32 L2A Series, Reference Manual, Page: 1282 / 1379

3. If TSIcounter < 3, go to step 8
4. If Rs = minrs, go to step 6.
5. Reduce value of Rs. go to step 2
6. If Dvolt = maxDv, go to END
7. Increase value of Dvolt. Set Rs = maxrs. go to step 2
8. If Rs > minrs, (Reduce value of Rs, go to END)
9. Rs = maxrs, reduce value of Dvolt.
10. END Get value of Rs and Dvolt.
One example of noise detection mode is shown in the following figure. in this figure the
TSI is working in capacitive mode until 28 µs (T1) when it is changed to noise detection
mode. In noise detection mode the selected pad is biased with 0.815V and all AC
waveform in this pad is caused by a noise source external to the MCU.
It is possible to observe in the following figure that, in noise detection mode, the clkref
output has the peak detection and the number of detected peaks can be counted or used by
digital block. The clkext output has the internal oscillator output and can be used to set
the maximum noise detection time window.
The waveform of the following figure shows two operations during noise detection mode:
• The V(vp) and V(vm) thresholds are changed in 34.4 µs (T2).
• The Rs series resistance value is changed between 184 kΩ
(TSI_GENCS[EXTCHRG]=011b), 77 kΩ (TSI_GENCS[EXTCHRG]=100) and 32
kΩ(TSI_GENCS[EXTCHRG] = 101). Because of this Rs change the amplitude of
noise waveform change also.
Functional description
K32 L2A Reference Manual, Rev. 2, 01/2020
1282 NXP Semiconductors