User Manual

Smart Machine Smart Decision
SIM7100_Hardware_Design_V1.02 2015-06-16
until the call is answered or hung up.
Figure 19: RI behaviour（voice call）
Note: For more details of AT commands about UART, please refer to document [1] and [22].
DTR pin can be used to wake SIM7100 from sleep. When SIM7100 enters sleep mode, pulling
down DTR can wake SIM7100.
3.4 USB Interface
The SIM7100 contains a USB interface compliant with the USB2.0 specification as a peripheral,
but the USB charging function is not supported.
3.4.1 USB Application Guide
SIM7100 can be used as a USB device. SIM7100 supports the USB suspend and resume
mechanism which can reduce power consumption. If there is no data transmission on the USB bus,
SIM7100 will enter suspend mode automatically, and will be resumed by some events such as
voice call or receiving SMS, etc.
Figure 20: USB Reference Circuit
Because of the high bit rate on USB bus, more attention should be paid to the influence of the
junction capacitance of the 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 ESD9L5.0ST5G
provided by On Semiconductor (www.onsemi.com ).
Note ： The USB_DN and USB_DP nets must be traced by 90Ohm+/-10% differential impedance.