Atmel SAM4S-EK, User Manual

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Evaluation Kit Hardware
4-8 SAM4S-EK Development Board User Guide
11139A–ATARM–29-Nov-11
4.3.13 Touch Screen Interface
The LCD module integrates a 4-wire touch panel controlled by MN7 (ADS7843) which is a slave device
on the SAM4S SPI bus. The controller sends back the information about the X and Y positions, as well
as a measurement for the pressure applied to the touch panel. The touch panel can be used with either
a stylus or a finger.
The ADS7843 touch panel controller connects to the SPI0 interface via the NPCS0 control signal. Two
interrupt signals are connected and provide events information back to the microcontroller: PenIrq and
Busy.
Note: PenIrq (PA16) is shared with ZigBEE signal IRQ0.
Busy (PA17) is shared with ZigBEE signal IRQ1.
Therefore, if using a ZigBEE interface in concurrence with the TouchScreen controller, take
care not to have both drivers enabled at the same time on either PA16 or PA17.
For that purpose, 0 Ohm resistors have been implemented on these PIO lines in order to disconnect
either end driver from the other:
„ On the touch panel controller side, R67 and R69.
„ On ZigBEE side, R117 and R120.
for further information, refer to the “Schematics” section.
Touch ADC auxiliary inputs IN3/IN4 of the ADS7843 are connected to test point (TP8, TP9) for optional
function extension.
Figure 4-10. Touch Panel Control
4.3.14 JTAG/ICE
A standard 20-pin JTAG/ICE connector is implemented on the SAM4S-EK for the connection of a com-
patible ARM JTAG emulator interface, such as the SAM-ICE from Segger.
Notes: 1. The NRST signal is connected to BP1 system button and is also used to reset the LCD
module. The 0 ohm resistor R44 may be removed in order to isolate the JTAG port from
this system reset signal.
2. The TDO pin is in input mode with the pull-up resistor disabled when the Cortex M3 is
not in debug mode. To avoid current consumption on VDDIO and/or VDDCORE due to
floating input, the internal pull-up resistor corresponding to this PIO line must be
enabled.
PA12
PA13
PA14
PA17
PA11
X_RIGHT
Y_UP
X_LEFT
Y_DOW N
PA16
DGND
+3V3
+3V3
+3V3
AGND_TP AGND_TP
R62
100K R62
100K
R70 0R R70 0R
R67 0R R67 0R
R66 0R R66 0R
R65
100K R65
100K
C60
100nF C60
100nF C58
100nF C58
100nF
L2
10uH/100mA L2
10uH/100mA
R72
100K R72
100K
R69 0R R69 0R
C61
4.7uF C61
4.7uF
TP9
SMD TP9
SMD
R71
1R R71
1R
C59
100nF C59
100nF
TP8
SMD TP8
SMD
R74
0R R74
0R
R73
100K R73
100K
MN7
ADS7843E MN7
ADS7843E
XP
2
YP
3
XM
4
YM
5
DCLK
16
DIN
14
DOUT
12
CS
15
BUSY
13
PENIRQ
11
VREF
9
VCC1
1
VCC2
10
GND
6
IN3
7
IN4
8