Freescale Semiconductor MCF52277 Reference Manual page 505

BIACTRL
Pen
SELREFP
SELREFN
det ect i on
SELINP
a
PENDOWN_IRQ
ASPE
FIFO_WM_IRQ
BIACTRL
SELREFP
AZX
SELREFN
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 measurements.
f) ASP completes one round of auxiliary channel measurements.
g) If the FIFO watermark level is set to the same number of active auxiliary channels plus four,
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 measurement.
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 the 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 AZE is cleared, remove the AZX and AZY measure phases.
Freescale Semiconductor
Pen X M
AZX
det ect i on M easur e I DLE
e
b c
d
Figure 22-19. Mode 11 Auto, Part 1
X M
Y
AZY
M easur e I DLE
M easur e
Figure 22-20. Mode 11 Auto, Part 2
MCF52277 Reference Manual, Rev. 1
Touchscreen Controller/Analog-to-Digital Converter
Y M U
i
AZY
M easur e I DLE M easur e
M U M U
i 1
I DLE M easur e I DLE M easur e
NOTE
M U R Pen
1
I DLE M easur e I DLE det ect i on
f
g h
R Pen Pen
AZX
I DLE det ect i on det ect i on
j p
k l
m o
n
22-25