Touchscreen Calibration – Auto - Freescale Semiconductor MCF52277 Reference Manual

Touchscreen Controller/Analog-to-Digital Converter
BIACTRL
SELREFP
SELREFN
SELINP
ASPE
FIFO_WM_IRQ
a) ASP configuration is complete, and waits for ASPE to be set.
b) MCU sets ASPE to initiate the calibration process.
c) FIFO watermark interrupt occurs when the watermark level is equal to the amount of data
captured.
d) ASP responds to the interrupt by clearing the ASPE bit.
e) ASP clears the FIFO watermark interrupt by uploading the data from the FIFO.
If MIDLECNT is equal to zero, remove the IDLE measurement phase.
22.5.11 Touchscreen Calibration – Auto
Touchscreen calibration auto is similar to the single round in capturing the calibration data set. However,
it improves the calibration precision by repeating the process.
Figure 22-25 and Figure 22-26
AUTO = 1. (MODE, AZE, and PENE have no effect.) The following example assumes MIDLECNT ≠ 0
and RIDLECNT ≠ 0.
BIACTRL
SELREFP
SELREFN
SELINP
ASPE
FIFO_WM_IRQ
22-28
CALA
1
I DLE
M easur e
a
b
Figure 22-24. Touchscreen Calibration Single Round
illustrate a typical operation sequence when TSE = 1, CALA = 1, and
CALA M
1
I DLE
M easur e I DLE
a
b
Figure 22-25. Touchscreen Calibration Auto, Part 1
MCF52277 Reference Manual, Rev. 1
M CALA M
i
I DLE M easur e I DLE
NOTE
NOTE
CALA M CALA
i
M easur e I DLE M easur e
CALA
n
I DLE
M easur e
d
c e
R CALA M
n 1
I DLE M easur e I DLE
c d
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