TOBY-L4 series - System Integration Manual
UBX-16024839 - R04
System description
Page 38 of 143
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
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 2.4.2 for the antenna detection circuit on the application board and the diagnostic circuit in the
antenna assembly design-in guidelines.
1.8
SIM interfaces
1.8.1
SIM interfaces
TOBY-L4 series modules provide two SIM interfaces for the direct connection of two external SIM cards/chips,
which can be used alternatively (only one SIM at a time can be used for network access):
SIM0 interface (
VSIM
,
SIM_IO
,
SIM_CLK
,
SIM_RST
pins), which is enabled by default
SIM1 interface (
VSIM1
,
SIM1_IO
,
SIM1_CLK
,
SIM1_RST
pins), which can be alternatively enabled by
dedicated AT command
7
(see the
u-blox AT Commands Manual
[2]), or by means of the uCPU application
8
.
Both 1.8 V and 3 V SIM types are supported by the SIM interfaces. Activation and deactivation with an
automatic voltage switch from 1.8 V to 3 V is implemented according to ISO-IEC 7816-3 specifications.
High-speed SIM/ME interface and the PPS procedure for baud-rate selection is implemented according to the
values proposed by the SIM card/chip.
Both the
VSIM
supply output and the
VSIM1
supply output provide internal short circuit protection to limit the
start-up current and protect the SIM from short circuits.
1.8.2
SIM detection interface
The
GPIO5
pin of TOBY-L4 series modules can be configured to detect the mechanical / physical presence of an
external SIM card connected to the SIM0 interface. The pin 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.
The optional function “SIM card hot insertion/removal” can be additionally configured on the
GPIO5
pin, in
order to enable / disable the SIM0 interface upon detection of external SIM card physical insertion / removal.
7
Not supported by the "00" product version
8
Not supported by the "50" product version
