Information

When the electrode scan unit starts a scan sequence, all the active electrodes will be
scanned sequentially, with each electrode having a scanned time defined by the
GENCS[NSCN]. The counter value is the sum of the total scan times of that electrode.
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Scan
States
Result
Counter
End-of-Scan
Signal
Count from 0 to result
Count from 0 to result Count from 0 to result
1st Scan
1st Scan
Last Scan
Last Scan
Last Scan
1st Scan
First Active
Electrode
Second Active
Electrode
Last Active
Electrode
Figure 51-41. Scan sequence
51.7.3.4.2 Low-power mode scan
In low-power periodic scan, the scan period is define by GENCS[LPSCNITV]. The TSI
module is enabled only in low-power modes only if GENCS[STPE] is 1.
All electrodes can operate in low power modes except in the low leakage modes. In low
leakage modes (LLS, VLLSx) only one electrode pin is functional, it's defined by the bit
field PEN[LPSP].
51.7.3.4.3 End-of-scan interrupt
The electrode scan unit sets the EOSF flag in the GENCS registers after all the active
electrode scan finishes. The EOSF flag generates an end-of-scan interrupt request if it is
enabled.. The interrupt is asserted if enabled by GENCS[TSIIE] and GENCS[ESOR].
The GENCS[EOSF] indicates that all active electrode scans are finished and the
respective capacitance results are in the TSICHnCNT registers. The GENCS[EOSF] is
cleared by writing 1 to it.
Functional description
K20 Sub-Family Reference Manual, Rev. 1.1, Dec 2012
1434
Preliminary
Freescale Semiconductor, Inc.
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