WH-LTE-7S1-E Hardware Manual
Technical Support:
Jinan USR IOT Technology Limited
www.pusr.com
8
3.2. USB Interface
7S1-E module provides a standard USB2.0 interface, supports both High Speed (480Mbps) and Full Speed
(12Mbps) circuits, supports suspend and resume, and can work in HOST mode and DEVICE mode. The USB
interface can map multiple serial ports on the PC by cooperating with the driver. The recommended circuit is
shown in the figure below. The typical voltage of USB interface power supply (USB_VCC) is 5V (range: 4.75 ~
5.25V). According to the different requirements of application products, should consider different
requirements of ESD and EMI. Design recommendations:
1. We recommend a common-mode suppression filter or 0 ohm resistor in the USB circuit to facilitate
subsequent debugging.
2. When used as an operation interface or debugging interface, the protection of ESD interface must be
considered on the USB signal line, the junction capacitance of ESD is not more than 3pF. TVS
recommends SEMTECH's RClamp0521P.TCT or INFINEO's ESD0P2RF-02LRHE6327. Other devices of the
same specification can also be selected according to the parameters.
3. USB_DP and USB_DM must be in differential signal, try to keep the two lines the same length, keep the
differential impedance at 90ohm.
4. USB_DP and USB_DM need to be protected by the ground.
PIN
Symbol
Description
Type voltage
3
USB_DM
USB D-
4
USB_DP
USB D+
8
VBUS
USB Power supply
5V
Reference circuit:
3.3. UART Interface
WH-LTE-7S1-E supports below baud rate:
1200
，
2400
，
4800
，
9600
，
19200
，
38400
，
57600
，
115200
，
230400
，
460800
，
921600
When the I/O of the user's MCU is not 3.0V, level matching is needed to achieve communication with
WH-LTE-7S1-E module. The conversion circuit is as follows: