User's Manual
Table Of Contents
- ZTEWelink Hardware Development Guide of ZM8620_V2 Module Product_V2.3.pdf
- Legal Information
- 1 About This Document
- 2 Product Overview
- 3 Mechanic Feature
- 4 Pin Description
- 5 Electric Feature
- 6 Related Test & Testing Standard
- 7 RF Specifications
- 8 Antenna
- 9 Debugging Environment and Method
- 10 Package System
- 11 Safety Information
- 12
Hardware Development Guide of Module Product
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ZM8620_V2
4.5.2 Electric Feature
The USB interface of Module complies with the USB2.0 specifications and the electrical characteristics.
During the PCB wiring, the wires must be parallel, the distance should be as short as possible and as far
away as possible from the antenna, and it‘s enveloped by the ground wires to avoid strong interference
sources. USB_DP and USB_DM should be wired strictly in the differential mode, and the length
difference of the two signals is within 1mm.
NOTE:
The differential resistance needs to be controlled within 90Ω, and the difference cannot exceed 5%.
It is recommended to cascade the high-speed common-mode rejection filter on the USB differential
traces. If some of the trace is exposed, it is recommended to add the ESD protection device, and the
junction capacitor of the ESD protection device should better be kept within 1.5pF. Large junction
capacitor will distort the waveform, and affect the bus communication.
4.6 UART Interface
The UART interface is used as MODEM port by default which is occupied by data service.
4.6.1 Description of PINs
The wireless module ZM8620_V2 supports the full UART interface with flow control function, which
complies with the RS-232 interface protocol, and supports the 8-wires serial bus interface or 2-wires
serial interface. The module can perform the serial communication and AT instruction interaction with
external.
This UART port supports the programmable data width, programmable data stop bit and programmable
parity check, and has an independent TX and RX FIFOs (512 bytes for each). For the normal UART
application (non-Bluetooth), the maximum baud rate is 230400bps, and the default baud rate is
115200bps. The PINs are defined as shown in Table 4-5.
Table 4–5 Definition of UART Signal
PIN
Signal Name
Description
Level
11
UART1_RX
UART port RX receive data
Power level is 3.3V.
13
UART1_TX
UART port TX transmit data
Power level is 3.3V.