Usb Interface; Usb Application Guide - SIM Tech SimCom SIM7100 Hardware Design

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status. Initially it keeps high, when a voice call or CSD call comes, the pin "RI" will change to low for
about 5900ms, then it will return to high level for 100ms. It will repeat this procedure until this call is
answered or hung up.
Figure 19: RI behaviour in FULL Modem
Note: For more details of AT commands about UART, please refer to document [1] and [22].
3.4

USB Interface

SIM7100 module contains a USB interface. This interface is compliant with the USB2.0 specification as a
peripheral or embedded host. USB charging is not supported.
3.4.1

USB Application Guide

Normally, SIM7100 is a USB device. SIM7100 supports the USB suspend and resume mechanism which
can help to save power. If no transaction is on USB bus, SIM7100 will enter suspend mode. When some
events such as voice call or receiving SMS happen, SIM7100 will resume normal mode automatically.
Figure 20: USB Reference Circuit
Because of high bit rate on USB bus, please pay attention to influence of junction capacitance of ESD
component on USB data lines. Typically, the capacitance should be less than 1pF. It is recommended to
use an ESD protection component such as ON SEMI (www.onsemi.com ) ESD9L5.0ST5G.
：
Note The SIM7100 has two kinds of interface (UART and USB) to connect to host CPU. For example,
On windows XP operating system, USB interface is mapped to 6 virtual ports: "SIMTECH HS-USB
Modem 9001", "SIMTECH HS-USB AT port 9001", "SIMTECH HS-USB Audio 9001", "SIMTECH
HS-USB Diagnostics 9001", "SIMTECH HS-USB NMEA 9001" and "SIMTECH Wireless HS-USB
Ethernet Adapter 9001".
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SIM7100_Hardware Design_V1.01 2015-01-20