TSI software configurations
KE15Z Touch Sensing Interface, User's Guide, Rev. 0, 12/2016
NXP Semiconductors
15
There’s an example of the clock generation configuration for the mutual mode.
PRBS is enabled by setting SSC Mode = 00, then the SSC t2 is random. Setting SSCHighRandomWith
as 6 means the t2 ranges from 1×MainClock to 6×MainClock. As a result, the average t2 is
(1+6)/2=3.5×MainClock.
According to the formula of clock generation, the SwitchingClock = MainClock/(t1+t2+t3) =
16.65/(6+3.5+3) = 1.33MHz, as the parameter of prescale doesn’t take effect here.
SwitchingClock = 16.65/(6+(6+1)/2+3) = 1.33MHz
3.2.2. Scan time
The scan time determines how long the TSI finishes the scan and get conversion result. The typical
single scan time of the mutual mode is around 100us, when the TSI acquisition time (switching clock) is
configured as 1us. Similar to the self-mode configurations, the mutual mode also support multiple scan
per channel, and the scan number is configured by TSI_SINC [DECIMATION], [ORDER], and
[CUTOFF].
Please refer to the chapter of self-mode scan time for the detailed descriptions.
Untouched Touched
Delta
Main
Clock
(MHz)
Prescale
SSC
SSC High Width
ChargeNumber
t1
SSC High
Random
Width
t2
SSC
Low
Width
t3
Switching
Clock
(MHz)
5765
5920
155
16.65
16
ON
6
6
3
1.33
Counter
Clock Generation
