Atmel SAM4S-EK2 Atmel ATSAM4S-EK2 ATSAM4S-EK2 Data Sheet

11176A–ATARM–24-Sep-12

Using a readily available 1/8-in. (3,5 mm) stereo headphone jack, the control switch is closed when no 
plug is inserted. When closed, a 100-kOhm/1-kOhm divider pulls the ST/MN input low. When a jack plug 
is inserted, the 1-kOhm resistor is disconnected and the ST/MN input is pulled high. The mono speaker 
(J10 connector) is also physically disconnected from the RO/MO+ output so that no sound is heard from 
the speaker while the headphones are inserted.

The SAM4SD32 UDP port is compliant with the Universal Serial Bus (USB) rev 2.0 Full Speed device 
specification. J15 is a micro B-type receptacle for USB device.

Both 27-Ohm resistors R114 and R116 build up a 90-Ohm differential impedance together with the 
(embedded) 6-Ohm output impedance of the SAM4SD32 full speed channel drivers.

R110 and R112 build up a divider bridge from VBUS +5V to implement plug-in detection (5V level gets 
lowered to a PIO compatible 3.3V level) through PC21. 

Figure 4-14.  USB

The 2.5V voltage reference is based on a LM4040 (Precision Micropower Shunt Voltage Reference).

This ADVREF level can be set as 2.5V or 3.3V via the jumper JP2.

Figure 4-15.  Analog Vref

C9 4
10 pF

R1 16

27 R

DG ND

RV 2
V5 .5MLA0 603

PC21

PB 11

FG ND

RV 1
V5 .5MLA0 603

5V

D-

D+

ID

G

J1 5

TB D

US B Micro  B

1

2

3

4

7

5

6

8
9

10

11

R1 12

68 K

DG ND

R1 10

47 K

FG ND

R1 14

27 R

PB 10

ADVREF

DGND

DGND

VCC33

+5V

JP2

JP2

1

2

3

C5
100nF

C5
100nF

ADVREF

1

R13
2.2K

R13
2.2K

MN2

LM4040-2.5

MN2

LM4040-2.5

SAM4SD32