u-blox LARA-R2 series System Integration Manual Download

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LARA-R2 series - System Integration Manual

UBX-16010573 - R02

Objective Specification

System description

Page 34 of 148

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

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

[2] for more details on this feature.

The

ANT_DET

pin generates a DC current (for detailed characteristics see the

LARA-R2 series

Data Sheet

[1]) 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 2.4.2 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

LARA-R2 series modules provide 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 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

GPIO5

pin is by default configured to detect the external SIM card mechanical / physical presence. The pin is

configured as input, and it can sense SIM card presence as intended to be properly connected to the mechanical
switch of a SIM card holder as described in section 2.5:



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 / used or

not according to the application requirements: an Unsolicited Result Code (URC) is generated each time that
there is a change of status (for more details see

u-blox AT Commands Manual

[2], +UGPIOC, +CIND, +CMER).

The optional function “SIM card hot insertion/removal” can be additionally configured on the

GPIO5

pin by

specific AT command (see the

u-blox AT Commands Manual

[2], +UDCONF=50), in order to enable / disable the

SIM interface upon detection of external SIM card physical insertion / removal.