L830-EA M.2 Module Hardware User Manual
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switch signal.
In order to ensure signal completeness, the wire distance between the module and SIM card should
not exceed 100mm.
In order to avoid mutual interference, USIM_CLK and USIM_IO signals should be separated in wiring.
It would be best to wrap them with ground wire respectively.
SIM card signal line should be protected with ESD. These protective devices should have small
capacitance (like Zener diode, etc.). Users are recommended to select ESD devices with equivalent
capacitance lower than 33pF. During layout, ESD device should be close to the SIM card interface.
5.5.4 USIM Hot-Plugging
L830-EA M.2 module supports SIM card status-detection function. This function allows the hot-plugging of
SIM card.
5.5.4.1 Hardware Connection
SIM card hot-plugging function needs to work with SIM_DETECT signal.
SIM_DETECT will be at low level without SIM card; after inserting SIM card, SIM_DETECT will be at high
level.
Note :
For “Normal closed” SIM card, as shown in the figure 5-7, SIM_DETECT signal line is connected to
U2’s Pin8 (SW2), and Pin7 (SW1) is connected to the ground. When the SIM card is not inserted,
SW2 and SW1 short circuit, SW2 will be at low level. When the SIM card is inserted, SW2 and SW1
will be disconnected, SIM_DETECT level will be pulled up.
For “Normal opened” SIM card, as shown in the figure 5-8, SIM_DETECT signal line is connected to
U2’s Pin8 (SW2), and Pin7 (SW1) will be pulled up 4.7K resistor . When the SIM card is not inserted,
SW2 and SW1 will be disconnected, then SW2 will be at low level. When the SIM card is inserted,
SW2 and SW1 will short circuit, SIM_DETECT level will be pulled up.
5.5.4.2 Software Settings
“+MSMPD” configures AT command for the SIM card status-detection function.
If set AT+MSMPD=0, SIM card status-detection function will be closed, and the module will not detect
SIM_DETECT signal.
If set AT+MSMPD=1, SIM card status-detection function will be in operation, and the module will
detect if the SIM card is inserted by SIM_DETECT Pin.
If SIM_DETECT is at high level, which indicates SIM card is inserted, the module will automatically
register it to the network.
