Datasheet

721
32142D–06/2013
ATUC64/128/256L3/4U
The ADP pins are used by default, as the APOE bit is zero after reset. Writing a one to the
APOE bit instructs the ADCIFB Resistive Touch Screen Sequencer to use the already con-
nected ADtspo+0 and ADtspo+2 pins to drive VDD to X
P
and Y
P
signals directly. In this mode the
ADP pins can be used as general purpose I/O pins.
Before writing a one to the APOE bit the user must make sure that the I/O voltage is compatible
with the ADC input voltage. If the I/O voltage is higher than the maximum input voltage of the
ADC, permanent damage may occur. Refer to the Electrical Characteristics chapter for details.
Figure 29-3. Resistive Touch Screen Pin Connections
VAD
tspo 2+

R
filmy
R
filmy
R
resistory
+
-------------------------------------------- -
VDP
1
=
AD tspo+1
X
M
X
P
Y
M
Y
P
AD tspo+0
DP 1
DP 0
AD tspo+3
AD tspo+2
Analog Pin Output Enable (MR.APOE) == 0
AD tspo+1
X
M
X
P
Y
M
Y
P
AD tspo+0
DP 1
DP 0
AD tspo+3
AD tspo+2
Analog Pin Output Enable (MR.APOE) == 1
NC
NC