Touchscreen Calibration—Single Round - Freescale Semiconductor MCF52277 Reference Manual

SELREFP
SELREFN
SELINP
a
ASPE
FIFO_WM_IRQ
SELREFP
SELREFN
SELINP
FIFO_WM_IRQ
ASPE
a) ASP configuration is complete, and waits for ASPE to be set.
b) MCU sets ASPE to initiate the conversions.
c) ASP begins a round of conversions.
d) ASP completes one round of conversions.
e) If the FIFO watermark level is set to the number of active auxiliary channels, the FIFO
watermark interrupt occurs.
f) MCU uploads the conversion results, which clears the FIFO watermark interrupt.
g) Steps d–e repeat.
h) The last round of conversions is completed. (For this example, the required number of rounds
of conversions is done.)
i) FIFO watermark interrupt occurs.
j) MCU clears ASPE to stop the conversion.
k) MCU uploads the last round of conversion results, which clears the FIFO watermark interrupt.
If MIDLECNT is equal to zero, remove the IDLE measurement phase.
If RIDLECNT is equal to zero, remove the IDLE round phase.
22.5.10 Touchscreen Calibration—Single Round
Touchscreen calibration single round is used to capture one set of calibration data for correction for the
device and environment. The calibration process starts when ASPE is set. The size of the data set received
is dependent on the touchscreen interface type (e.g., 4 data for 4-wire).
Figure 22-24 illustrates a typical operation sequence when TSE = 1, CALA = 1, AUTO = 0. (MODE,
AZE, PENE, and RIDLECNT have no effect.) The following example assumes MIDLECNT ≠ 0.
Freescale Semiconductor
U M
n
I DLE
M easur e I DLE
c
b
Figure 22-22. General Purpose ADC Auto, Part 1
U M U
n i
M easur e I DLE M easur e
Figure 22-23. General Purpose ADC Auto, Part 2
MCF52277 Reference Manual, Rev. 1
Touchscreen Controller/Analog-to-Digital Converter
U M U
i 1
M easur e I DLE M easur e
M U R
1
I DLE M easur e I DLE
h
i
j
NOTE
R U M
n
I DLE M easur e I DLE
d
e
f
I DLE
k
22-27