42.4.13.1 Automatic noise mode
This mode is set by MODE[3:2] = 11 (noise mode 3). In this mode, the thresholds are
incremented internally by the module until the point that there is no noise voltage
trepassing the threshold.
The following diagram shows how it is done. The threshold comparator output goes to a
counter and as the DVOLT control bits are increased the DVOLT thresholds are
increased as well. The four bits are counted until 1111 (=15) and the counter is stop with
this maximum value.
Figure 42-17. Block diagram automatic noise threshold operation
The signals that have different behavior in this noise mode (wrt capacitive mode) are
shown in the following table.
Table 42-12. Signal properties in automatic noise operation mode
Name Function I/O type Power Up/Reset state
MODE[3:2] 11 - Noise mode operation
with frequency limitation and
automatic threshold counter.
I 00
Table continues on the next page...
Chapter 42 Touch Sensing Input (TSI)
KL25 Sub-Family Reference Manual, Rev. 3, September 2012
Freescale Semiconductor, Inc. 803
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