Schematic
1
1
2
2
3
3
4
4
D D
C C
B B
A A
Tinysine Electronics
Size:
DrawnBy: Date:
A4
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D:\Program
Checkedby:
Approvedby:
SheetName:
Doucument NO：
HuangChao
1
2014/5/5
*
RS232&RS485 Shield
Document Name:
RS232&RS485 Shield V1r1
Date:
Date:
1
*
*
Sheet NO: of
R
1
RE
2
DE
3
D
4
GND
5
A
6
B
7
VCC
8
U2
MAX481CSA
VCC
16
GND
15
C1+
1
V+
2
C1-
3
C2+
4
C2-
5
V-
6
T2OUT
7
R2IN
8
R2OUT
9
T2IN
10
T1IN
11
R1OUT
12
R1IN
13
T1OUT
14
U1 SP3232EEA
IOREF
2
5V
5
3.3V
4
RESERVED
1
RESET
3
GND
6
GND
7
Vin
8
TX->D1
16
D4
19
~D3
18
RX<-D0
15
D2
17
~D5
20
~D6
21
D7
22
A1
10
A4
13
A3
12
A0
9
A2
11
A5
14
~D9
24
D12
27
~D11
26
D8
23
~D10
25
D13
28
GND
29
AREF
30
SDA
31
SCL
32
J2 ARDUINO SHIELD R3 SOCKET
9
10
8
7
6
5
4
3
2
1
J1
18688
GND
+5V
HARD_TX
HARD_RX
C3
100n/50V
C5
100n/50V
C2 100n/50V
C4 100n/50V
GND
+5V
+5V
GND
C1
100n/50V
GND
1
6
2
7
3
8
4
9
5
MT1
MT2
J3
618 009 231 121
GND
GND
RS232_TX
RS232_RX
GND
3
5
1
2
6
4
SW1 AYZ0202AGRL
SOFT_RX
SOFT_TX
HARD_TX
HARD_RX
SOFT_RX
SOFT_TX
MCU_RX
MCU_TX
3
5
1
2
6
4
SW2 AYZ0202AGRL
UART_RX_232
UART_TX_232
UART_TX_485
UART_RX_485
UART_RX_232
UART_TX_232 RS232_TX
RS232_RX
UART_RX_485
UART_TX_485
+5V
GND
C7100n/50V
GND
1
2
J7
SH133-3.5-2P
RS485_A
RS485_B
RS485_B
RS485_A
1
32
Q1 FDN340P
R1
1K
LED1
LED(GREEN)
GND+5V
1
32
Q2 FDN340P
R2
1K
LED2
LED(RED)
GND+5V
MCU_TX
MCU_RX
+5V
1
32
Q3
LBSS123LT1G
R4
10K
R3
10K
GND
+5V
UART_TX_485
C6
10u/16V/TA
+5V
GND
8
7
6
5
4
3
2
1
J5
18688
8
7
6
5
4
3
2
1
J4
18688
1
2
3
4
5
6
J6
18688
Cannot
open file
D:\Program
Files\Altiu
LOGO1
GND
GND
M1 M2
R5
10K
+5V
DIR_AUTO_485
DIR_MANUAL_485
1 3
2
SJ1
SJ_3SDIR_MANUAL_485
DIR_AUTO_485
R8
1K
R6
1K
R7
120R
+5V
GND 1
2
J10
SH133-3.5-2P
GND
+5V
SW
HW RS485
RS232
If you use the RS232 port,please slide the SW2 to the RS232 side
If you use the RS485 port,please slide the SW2 to the RS485 side
If you use the hardware serial port,please slide the SW1 to the HW side
If you use the soft ware serial port,please slide the SW1 to the SW side
If you set to auto mode,that means you don't need a GPIO pin to control the RS485 data direction.
The UART_TX_485 with the FET(Q3) will help control the direction,but it's not perfect.
U
T
D
pull up
terminal
pull down
In this case,the RS485 bus should be pulled up with resistor.otherwise the high level bit of send byte can't be sent to the RS485 BUS.
If you use the manual mode,this mean you need a GPIO pin(D4) to control the RS485 data direction
If all nodes on the RS485 bus are in receiving mode, the bus voltage is zero, the voltage may case the receiver output zero to mcu.
You should use the pull-up resistor and one pull-down resitor on the RS485 BUS
If the bus line are very long, You should use the terminal resistor
1 2
3 4
5 6
J8
WUERTH 613 006 211 21