User's Manual

Reproduction forbidden without Fibocom Wireless Inc. written authorization - All Rights Reserved.
L850-GL Hardware User Manual Page
33
of
51
Figure 3-13 Reference Circuit for N.O. SIM Card Slot
The principlesof theN.O.SIM card slot are described as follows:
When the SIM card is detached, it connects an open circuit between CD and SW pins, and drives
the SIM_DETECT pin low.
When the SIM card is inserted, it connects the short circuit between CD and SW pins, and drives the
SIM_DETECT pin high.
3.6.3 USIM Hot-Plugging
The L850 module supports the SIM card hot-plugging function, which determines whether the SIM card is
inserted or detached by detecting the SIM_DETECT pin state of the SIM card slot.
The SIM card hot-plugging function can be configuredby AT+MSMPD” command, and the description for
AT command as shown in the following table:
AT Command
Hot-plugging
Detection
Function Description
AT+MSMPD=1
Enable
Default value, the SIM card hot-plugging detection function is
enabled.
The module can detect whether the SIM card is inserted or not
through the SIM_DETECT pin state.
AT+MSMPD=0
Disable
The SIM card hot-plugging detect function is disabled.
The module readsthe SIM card when starting up, and the
SIM_DETECT status will not be detected.
After the SIM card hot-plugging detection functionis enabled, the module detects that the SIM card is
insertedwhen the SIM_DETECT pin is high, then executes the initialization program and finish the