Touchscreen Mode 11—Single Round - Freescale Semiconductor MCF52277 Reference Manual

BIACTRL
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SELREFP
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SELREFN
M easur e
SELINP
FIFO_WM_IRQ
PENUP_IRQ
ASPE
a) When ASP configuration is complete, the ASP parks on the pen detection state.
b) Pen-down event is detected and the pen-down interrupt occurs.
c) MCU responds to the interrupt and masks the pen-down interrupt. It is recommended to clear
the FIFO in this step.
d) MCU sets ASPE to initiate the measurement operation.
e) ASP begins the continuous auxiliary channel measurements.
f) ASP completes one round of measurements.
g) If the FIFO watermark level is set to the same number of active auxiliary channels, the FIFO
watermark interrupt occurs.
h) MCU uploads the conversion results, which clears the FIFO watermark interrupt.
i) Steps f–h repeat.
j) ASP completes the last round of auxiliary channel measurements.
k) FIFO watermark interrupt occurs.
l) MCU uploads the conversion results, which clears the FIFO watermark interrupt.
m) Pen-up event is detected and the pen-up interrupt occurs.
n) ASPE is cleared automatically after detection of pen-up interrupt.
o) MCU clears the pen-up and pen-down interrupt.
p) One extra conversion state is run by the state machine, but ASPE being cleared blocks the real
conversion operation by the ADC and no extra data is written into the FIFO.
If MIDLECNT is equal to zero, remove the IDLE measurement phase.
If RIDLECNT is cleared, remove the IDLE round phase.
If PENE is cleared, no pen-detection phase is after the end of the round.
Software must stop the conversion.
22.5.6 Touchscreen Mode 11—Single Round
Touchscreen mode 11 single round is used for touchscreen-controlled X/Y coordinate and auxiliary
channel measurement. One touch only results in one round of measurement.
Freescale Semiconductor
M U M
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I DLE M easur e I DLE M easur e
Figure 22-17. Mode 10 Auto, Part 2
MCF52277 Reference Manual, Rev. 1
Touchscreen Controller/Analog-to-Digital Converter
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