Use Instructions

Table Of Contents
L710HG Hardware Design
27
distortion, the impact of bus communication. Differential impedance of differential data line in 90ohm
+ 10%.
VUSB
GND
GND
USB_DM
USB_VBUS
USB_DP
MODULE
D1
D2
ZENER
ESD
ESD
ESD
C2
1UF
USB_DM
USB_DP
1
2
3
5
D3 D4
HOST
Figure 3-10 USB application
3.8 UART Interface
3.8.1 Pin description
L710HG module provides a flexible 7-wire UART (universal asynchronous serial transmission)
interface. UART as a full asynchronous communication interface, Support the standard modem
handshake signal control, Comply with the RS - 232 interface protocols. And also support four wire
serial bus interface or the 2-wire serial bus interface mode, and the module can be through the UART
interface for serial communication with the outside (DET) and the AT command input, etc. L710HG
module is a DCE (Data Communication Equipment) and client PC is a DTE (Data Terminal
Equipment).AT commands are entered and serial communication is performed through UART
interface. The pin signal is defined as shown in below table.
Table 3-12 UART pin definition
Pin No.
Pin
I/O
type
Descriptions
54 UART_TX
DO UART data transmission
53 UART_RX
DI UART data receive
55 UART_RI
DO
Ring Indicator.
51 UART_RTS
DO UART DET request to send
57 UART_DTR
DI DTE get ready.
52 UART_CTS
DI UART Clear to Send.