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SARA-R4 series - System integration manual
UBX-16029218 - R20
System description
Page 34 of 128
C1-Public
1.7.3
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-R4 series AT commands manual
for more details on this feature.
The
ANT_DET
pin generates a DC current (for detailed characteristics see the SARA-R4 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 interface
SARA-R4 series modules provide a SIM interface on the
VSIM
,
SIM_IO
,
SIM_CLK
,
SIM_RST
pins to
connect an external SIM card or UICC chip.
SARA-R410M and SARA-R412M modules support both 1.8 V and 3.0 V types of SIM / UICC, with
automatic voltage switch implemented according to related specifications.
SARA-R422, SARA-R422S and SARA-R422M8S modules support only the 1.8 V type of SIM / UICC.
1.8.2
SIM detection interface
The
GPIO5
pin is configured as an external interrupt to detect the SIM card mechanical / physical
presence. The pin is 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
For more details, see the SARA-R4 series AT commands manual
, +UGPIOC, +CIND and +CMER AT
commands.