SARA-G450 - System integration manual
UBX-18046432 - R08
System description
Page 28 of 143
C1-Public
1.7.2
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 the 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 u-blox AT commands manual
for more details on this feature.
The ANT_DET pin generates a DC current 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 design-in guidelines for antenna detection circuits on an application board and
diagnostic circuits on an antenna assembly.
1.8
SIM interface
1.8.1
(U)SIM card interface
SARA-G450 modules provide a high-speed SIM/ME interface, including automatic detection and
configuration of the voltage required by the connected (U)SIM card or chip.
Both 1.8 V and 3 V SIM types are supported: activation and deactivation with automatic voltage
switching from 1.8 V to 3 V is implemented, according to ISO-IEC 7816-3 specifications. The VSIM
supply output pin provides internal short circuit protection to limit start-up current and protect the
device in short circuit situations.
The SIM driver supports the PPS (Protocol and Parameter Selection) procedure for baud rate
selection, according to the values determined by the SIM card.
1.8.2
SIM card detection interface (SIM_DET)
The SIM_DET 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 properly connected to the mechanical switch of a SIM card holder as
described in section
Low logic level at SIM_DET input pin is recognized as SIM card not present
High logic level at SIM_DET input pin is recognized as SIM card present
The SIM card detection function provided by SIM_DET pin is an optional feature that can be
implemented / used or not according to the application requirements: an Unsolicited Result Code
(URC) can be generated each time that there is a change of status (for more details, see the “simind”
value of the <descr> parameter of +CIND and +CMER commands in u-blox AT commands manual
