Evaluation Kit Hardware
4-12
SAM4S-EK Development Board User Guide
11139A–ATARM–29-Nov-11
4.3.18.2 Analog Input
The BNC connector CN1 is connected to the ADC port PB1 as an external analog input. An on-board 50-
Ohm resistor termination can be applied by closing jumper JP16. A low pass filter can be implemented
for the BNC connector CN1 by replacing R94 and C78 with custom resistor and capacitor values,
depending on your application requirements.
A 10-KOhm potentiometer (VR1) is also connected to this channel to implement an easy access to ADC
programming and debugging (or implement an analog user control like display brightness, volume, etc.).
Either of these two functions can be selected by jumper JP18.
Figure 4-16.
ADC Input
4.3.18.3 Analog Output
The BNC connector CN2 is connected to the DAC port PB14 and provides an external analog output. An
on-board 50-Ohm resistor termination can be enabled by closing jumper JP21. A filter can be imple-
mented on this output channel by replacing R106 and C90 with appropriate resistor and capacitor
values, depending on the application requirements.
Figure 4-17.
DAC Output
4.3.19
QTouch Elements
QTouch keys consist in a series of sensors formed by the association of a copper area and the capaci-
tive effect of human fingers approaching it.
4.3.19.1 Keys
The SAM4S-EK implements five individual capacitive touch keys (UP, DOWN, RIGHT, LEFT and
VALID) using five pairs of PIO.
Potentiometer
AD5
ADC
DGND
DGND
VCC33
PB1
JP18
JP18
1
2
3
CN1
BNC
CN1
BNC
JP16
Header2
JP16
Header2
VR1
10K VR
VR1
10K VR
1
3
2
R96
49.9R
R96
49.9R
C89
10nF
C89
10nF
R94
0R
R94
0R
C78
10nF
C78
10nF
SOLDER DROP 2 pins open.Normal
DAC01
DAC
AUDIO_OUTL
DGND
PB14
C90
2.2uF
C90
2.2uF
JP21
JP21
R109
49.9R 1%
R109
49.9R 1%
SD1
SD1
1
2
R106
0R
R106
0R
CN2
BNC
CN2
BNC
1
2
3
4
5
SD2
SD2
1
2
