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FIBOCOM NL668-EAU-MiniPCIe-10 Hardware User Manual
Page 27 of 56
Note:
The USIM_PRESENCE is in high level by default, and can be switched to low level by AT
command.
AT command
Function description
AT+GTSET=”SIMPHASE”,1
High level detect by default
AT+ GTSET=”SIMPHASE”,0
Low level detect
Table 3-11 USIM_PRESENCE Effective Level Switch AT Command
3.5.4 (U)SIM Design Requirements
(U)SIM card circuit design shall meet EMC standards and ESD requirements, and at the same time, shall
improve anti-interference ability to ensure that the SIM card can work stably. The design needs to strictly
observe the following rules:
(U)SIM card slot is placed as close to the module as possible, away from the RF antenna, DCDC
power, clock signal lines and other strong interference sources;
Adopt the (U)SIM card slot with metal shield shell to improve anti-interference ability;
The length of cable from the module to the (U)SIM card slot shall not exceed 100mm. Longer cable
reduces signal quality.
USIM_CLK and USIM_DATA signals are isolated to avoid mutual interference. If it is difficult to do so,
(U)SIM signal needs to be protected as a set;
The filter capacitor and ESD device of SIM card signal cable are placed close to the (U)SIM card slot.
Select 22 ~ 33pF capacitor for ESD device equivalent capacitor.
3.6 UART Interface
3.6.1 UART Interface Definition
Module has two serial ports: the main serial port and debug serial port. The following describes the main
features of these two serial ports: the main serial port supports 4800bps, 9600bps, 19200bps, 38400bps,
57600bps, 115200bps, and 230400bps baud rate. The default baud rate is 115200bps, used for data
transmission and AT command transmission.
Debug serial port supports 115200bps baud rate for FIBOCOM internal debugging.
The following table describes the main serial port pin:
Pin Name
I/O
Pin Num
Description
UART_CTS
I
30
Clear transmission
UART_RTS
O
25
Requests transmission
