SAM4E-EK User Guide
42067A
−
SAM4E
−
01/2013
12
4.3.6 UART
The Universal Asynchronous Receiver Transmitter features a two-pin UART that can be used for communication and
trace purposes. It offers an ideal channel for in-situ programming solutions. This UART is associated with two PDC
channels to reduce the processor time on packet handling.
This two-pin UART (TXD and RXD only) is buffered through an RS232 Transceiver MN6 and brought to the DB9 male
connector J7.
Figure 4-5. UART.
R58
100K
C54
100nF
R62
0R
TP4
MN7
ADM3202
T1IN
11
T2IN
10
R1OUT
12
R2OUT
9
T1OUT
14
T2OUT
7
R1IN
13
R2IN
8
V+
2
C1+
1
C1-
3
C2+
4
C2-
5
V-
6
VCC
16
GND
15
J7
5
4
3
2
1
9
8
7
6
10
11
C53
100nF
C57
100nF
TP5
R60
0R
C55
100nF
R59
100K
C56
100nF
+3V3
+3V3
FGND
+3V3
PA9
PA10
UTXD0
URXD0
DBGU
4.3.7 USART
The Universal Synchronous/Asynchronous Receiver Transmitter (USART) provides one full duplex universal
synchronous/asynchronous serial link. The data frame format is extensively configurable (data length, parity, number of
stop bits) to support a broad range of serial communication standards. The USART is also associated with PDC
channels for TX/RX data access.
To avoid any electrical conflict, the RS232 and RS485 transceiver are isolated from the receiving line PA21.
•
Chose RS485 channel: Close 1-2 pins on JP11 and set PA23 to high level
•
Chose RS232 channel: Close 2-3 pins on JP11 and set PA23 to low level
Figure 4-6. USART.
RXD1
PA21
PA21_232
C46
100nF
C44
100nF
R37
0R
C48
100nF
R40
0R
R42
0R
J5
5
4
3
2
1
9
8
7
6
10
11
R44
0R
MN5
ADM3312EARU
C1+
6
C1-
20
C2+
2
C2-
4
C3+
24
C3-
22
VCC
3
V+
1
V-
21
GND
23
SD
19
EN
5
T1IN
7
T1OUT
18
R1IN
15
R1OUT
10
T2IN
8
T2OUT
17
R2IN
14
R2OUT
11
T3IN
9
T3OUT
16
R3IN
13
R3OUT
12
C49
100nF
R39
0R
R41
0R
C45
100nF
R38
47K
C43
4.7uF
TXD1
R43
47K
C47
100nF
PA21_485
FGND
+3V3
+3V3
+3V3
PA25
PA24
RTS1
PA21_232
CTS1
PA22
USART1
PA23
JP11
1
2
3
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