User guide

Evaluation Kit Hardware
4-28 Evaluation Kit (EK) User Guide
11115A–ATARM–27-Jul-11
4.3.3.5 USART
The USART0 and USART3 are used as serial communication ports. Both USARTs are buffered with an
RS-232 Transceiver (TXD, RXD and handshake CTS/RTS control) and connected to the DB-9 male
socket. The software must assign the appropriate PIO pins to enable the USART function.
The USART3 is only supported by SAM9G25 and SAM9X25 processors. The RS-232 Transceiver for
USART3 is enabled by the signal SELCONFIG comprised of a pull down resistor on CM board. Ref to
Section 4.4.1 ”DM Board Overview” for details.
Figure 4-22. USART Com Port
(only for SAM9G25/SAM9X25)
VDDIOP1
VDDIOP1
R69 0R
R70 0R
PC24
EARTH_RS232
C32 100n
PC22
C34 100n
PC23
PC25
J12
5
4
3
2
1
9
8
7
6
10 11
C39 100n
R68 0R
RTSC3
TXDC3
R64
47k
CTSC3
C29
100n
C28
4.7u
C35 100n
RXDC3
R63
47k
C37 100n
R62
47k
R65 0R
R61
47k
R66 0R
CTS3
RXD3
RTS3
TXD3
SELCONFIG
MN9
ADM3312EARU
V+
1
C2+
2
VCC
3
C2-
4
EN
5
C1+
6
T1I N
7
T2I N
8
T3I N
9
R1OUT
10
R2OUT
11
R3OUT
12
R3IN
13
R2IN
14
R1IN
15
T3OU T
16
T2OU T
17
T1OU T
18
SD
19
C1-
20
V-
21
C3-
22
GND
23
C3+
24
USART3
USART0
R30 0R
R31 0R
PA0
PA2
C17 100n
C16 100n
EARTH_RS232
J8
5
4
3
2
1
9
8
7
6
10 11
PA1
PA3
C19 100n
R29 0R
RTS0
MN4
ADM3312EARU
V+
1
C2+
2
VCC
3
C2-
4
EN
5
C1+
6
T1I N
7
T2I N
8
T3I N
9
R1OUT
10
R2OUT
11
R3OUT
12
R3IN
13
R2IN
14
R1IN
15
T3OU T
16
T2OU T
17
T1OU T
18
SD
19
C1-
20
V-
21
C3-
22
GND
23
C3+
24
TXD0
L5
220ohm at 100MHz
1 2
CTS0
RTSC0
RXD0
TXDC 0
C13
4.7u
C14
100n
CTSC0
C15 100n
VDDIOP0
R24
47k
RXDC0
R23
47k
C18 100n
R27 0R
R22
47k
R28 0R
VDDIOP0