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SARA-R5 series - System integration manual
UBX-19041356 - R04
System description
Page 28 of 118
C1-Public
1.7.3
Cellular antenna detection interface (ANT_DET)
The antenna detection is based on ADC measurement. The
ANT_DET
pin is an analog to digital
converter (ADC) provided to sense the antenna presence.
The antenna detection function provided by
ANT_DET
pin is an optional feature that can be
implemented if the application requires it. The antenna detection is forced by the +UANTR AT
command. See the SARA-R5 series AT commands manual
for more details on this feature.
The
ANT_DET
pin generates a DC current (for detailed characteristics see the SARA-R5 series data
sheet
) and measures the resulting DC voltage, thus determining the resistance from the antenna
connector provided on the application board to GND. So, the requirements to achieve antenna
detection functionality are the following:
•
an RF antenna assembly with a built-in resistor (diagnostic circuit) must be used
•
an antenna detection circuit must be implemented on the application board
See section
for antenna detection circuit on application board and diagnostic circuit on antenna
assembly design-in guidelines.
1.8
SIM interface
1.8.1
SIM card interface
SARA-R5 series modules provide on the
VSIM
,
SIM_IO
,
SIM_CLK
and
SIM_RST
pins a high-speed
SIM/ME interface including automatic detection and configuration of the voltage required by the
connected SIM card or chip.
Both 1.8 V and 3 V SIM types are supported. Activation and deactivation with automatic voltage
switch from 1.8 V to 3 V are implemented, according to ISO-IEC 7816-3 specifications. The
VSIM
supply output provides internal short circuit protection to limit start-up current and protects the SIM
to short circuits.
1.8.2
SIM card detection interface (GPIO5)
The
GPIO5
pin can be configured as an external interrupt to detect the SIM card mechanical / physical
presence. The pin can be configured as input with an internal active pull-down enabled, and it can
sense SIM card presence only if cleanly connected to the mechanical switch of a SIM card holder as
described in section
•
Low logic level at
GPIO5
input pin is recognized as SIM card not present
•
High logic level at
GPIO5
input pin is recognized as SIM card present
The SIM card detection function provided by
GPIO5
pin is an optional feature that can be implemented
or not according to the application requirements. For more details
about “SIM card detection” feature
,
see the SARA-R5 series AT commands manual
, +UGPIOC, +CIND and +CMER AT commands.
If the
“SIM card detection”
feature is enabled in the application by the dedicated +UGPIOC AT
command, then it is recommended to also enable the additional
“SIM card hot insertion/removal”
feature by the dedUDCONF=50 AT command, in order to enable / disable the SIM interface
upon detection of the external SIM card physical insertion / removal. For more details about the
“SIM
card hot insertion/removal” feature, see
the u-blox AT commands manual
, +UDCONF=50 AT
command.