User Guide

GM500-U1G_A

Hardware Development Guide

RST 5 USIM card reset

VDD 6 USIM card power supply

2.9. USB Interface

GM500-U1G_A contains one integrated USB transceiver which complies with the USB 2.0 specification and supports high speed

(480 Mbps), full speed (12 Mbps) and low speed (1.5 Mbps) mode. The USB interface is primarily used for AT command, data

transmission, software debug and firmware upgrade. The following table shows the pin definition of USB interface.

Table 2-11USB Pin Description

Pin Name Pin NO. I/O Description Comment

USB_DP 24 IO USB differential data bus (positive) Require differential impedance of 90Ω

USB_DM 23 IO USB differential data bus (negative) Require differential impedance of 90Ω

USB_VBUS 22 DI USB plug detect pin, not USB power USB plug detect

GND 21 Ground

More details about the USB 2.0 specifications, please visit http://www.usb.org/home.

For different use purposes, different designs can be referred to:



 Connect USB interface to USB connector directly. The following figure shows the reference circuit of USB interface

Figure 2–14Reference Circuit of USB Application



Reference Circuit of USB Communication between module and AP is the one below. The 0Ω in the figure should be placed

near pin.