Quectel EC20 User Manual

LTE Module Series
EC20 Mini PCIe Hardware Design
EC20_Mini_PCIe_Hardware_Design Confidential / Released 21 / 36
UART_RX
UART_TX
DTR
RI
TXD
RXD
DTR
RI
EC20 Mini PCIe Application
DCE DTE
GND GND
Figure 6: The DCE-DTE Connection of UART Interface
The following figure is an example of connection between EC20 Mini PCIe and PC. Since the UART
interface does not support the RS-232 level, A RS-232 level translator IC must be inserted between
module and PC. A RS-232 level shifter SN65C3238 provided by Texas Instruments is recommended.
The following figure shows the reference design of RS232 level match circuit.
DTR
UART_RX
RI
UART_TX
EC20 Mini PCIe
GND
3.3V
DIN1
ROUT3
ROUT2
ROUT1
DIN4
DIN3
DIN2
DIN5
R1OUTB
FORCEON
/FORCEOFF
/INVALID
3.3V
DOUT1
DOUT2
DOUT3
DOUT4
DOUT5
RIN3
RIN2
RIN1
VCC GND
SN65C3238 DB9(PC)
DCD
RTS
DTR
TXD
RI
CTS
RXD
DSR
GND
1
2
3
4
5
6
7
8
9
Figure 7: RS232 Level Match Circuit
AT command AT+IPR is used to set the baud rate of the UART. Please refer to document [2] for details.
NOTE
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Quectel EC20 Specifications

General

Brand	Quectel
Model	EC20
Category	PCI Card
Language	English