Information

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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 49-71. Scan sequence
49.7.3.4.2 Low power mode scan
In low power periodic scan, the scan period is define by the 4-bit binary
GENCS[LPSCNITV]. The TSI module is enabled in low power modes only if the bit
GENCS[STPE] is 1.
Only one electrode pin is functional in the low power mode scan and its defined by the
bit-field PEN[LPSP].
49.7.3.4.3 End-of-scan interrupt
Once all the active electrodes are scanned, TSI scan unit will assert the end-of-scan flag.
Upon the end-of-scan event, each electrode conversion result will be loaded to the
corresponding counter register, compared with each threshold to determine if its value is
out of range specified by the threshold registers, and if the counter value is stuck at
extreme values(0x0000 or 0xFFFF), the corresponding error flag will also assert.
The electrode scan unit sets the EOSF flag in the GENCS registers once 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] bits.
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 one to it.
Chapter 49 Touch sense input (TSI)
K10 Sub-Family Reference Manual, Rev. 6, Nov 2011
Freescale Semiconductor, Inc. 1557