Atmel SMART SAM4C Series User Manual page 13

3.5 Communication Interfaces
3.5.1 Serial Port USART2 RS232
The USART2 is buffered with one RS-232 Transceiver ADM3312E (Analog Devices) and is connected to a DB9
connector. A classic implementation RS232 transceiver selection should include double source capability. The
USART2 connector with RTS/CTS handshake signal support is connected to the RS232 transceiver.
Features:
One RS232 transceiver connected to RXD2, TXD2, RTS2, and CTS2

One DB9 male connector

Required resistors and capacitors

Figure 3-10. USART2 RS232 Schematic
(TXD2)
(RXD2)
(RTS2)
(CTS2)
3.5.2 Serial Port USART2 RS485
The USART2 is buffered with an Analog Devices ADM3485 RS-485/RS-422 transceiver and is connected to a 3-
point jumper.
Features:
One RS485 transceiver connected to RXD2, TXD2 and RTS2, CTS2

One 3-point connector

Required resistors and capacitors

Figure 3-11. USART2 RS485 Schematic
13 SAM4C32-EK [USER GUIDE]
Atmel-11253A-ATARM-SAM4C32-EK-UserGuide_17-Sep-14
VDDMAIN
C47 C48 C49
4.7µF 100nF 100nF
C52
Do Not Populate 100nF
R25
VDDMAIN
47K/DNP
R R26 0R
PA10 R28 0R
PA9_232 R30 0R
PA14 R31 0R
PA15 R33 0R
R34 47K
VDDMAIN
VDDMAIN
R23
10K
PA9_485 R27 0R
(RXD2)
PA15 R29 0R
(CTS2)
PA14 R32 0R
(RTS2)
PA10 R36 0R
(TXD2)
PA9_485
JP15
PA9 2
PA9_232
USART2
MN3
ADM3312EARU
3 6
VCC C1+
C50
100nF
1 20
V+ C1-
2
C2+
21
V-
C51
100nF
4
C2-
23 24
GND C3+
19 C53
SD
100nF
5 22
EN C3-
7 18
T1IN T1OUT
10 15
R1OUT R1IN
8 17
T2IN T2OUT
11 14
R2OUT R2IN
9 16
R35 0R
T3IN T3OUT
12 13
R3OUT R3IN
RS 485
MN4
ADM3485ARZ VDDMAIN
1 8
RO VCC
C54
2 5
100nF
RE GND
3
DE
4 6
DI A
7
B
R37
JP16
120R
Male
Straight Angle
J3 J3
1
6
2
7
3
8
4
9
5
FGND
VDDMAIN
Do Not Populate
R24
3.3K/DNP
JP14
J4
1
2
3
JP17
FGND
Do Not Populate
3.3K/DNP
R38