u-blox LEXI-R422, Руководство по системной интеграции

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LEXI-R422 - System integration manual
UBX-23007449 - R02 System description Page 27 of 108
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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 AT commands manual
[2] for more details on this feature.
The ANT_DET pin generates a DC current (for detailed characteristics see the LEXI-R422 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 2.4.3 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
LEXI-R422 modules provide a SIM interface on the VSIM , SIM_IO , SIM_CLK , SIM_RST pins to connect
an external SIM card or UICC chip.
LEXI-R422 modules support only the 1.8 V type of SIM / UICC.
1.8.2 SIM detection interface
The GPIO6 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
2.5 :
•
Low logic level at GPIO6 input pin is recognized as SIM card not present
• High logic level at GPIO6 input pin is recognized as SIM card present
For more details, see the AT commands manual [2] , +UGPIOC, +CIND and +CMER AT commands.
1.9 Data communication interfaces
LEXI-R422 modules provide the following serial communication interfaces:
• UART interfaces: asynchronous serial interface supporting AT commands, data communication,
GNSS tunneling, FW update by means of FOAT. See section
1.9.1 .
• USB interface: High-Speed USB 2.0 compliant serial interface supporting FW update by means of
the u-blox EasyFlash tool and diagnostic trace logging. See section
1.9.2 .
• I2C interface: I2C bus compatible interface supporting communication with external u-blox GNSS
positioning chips or modules and with external I2C devices. See section
1.9.3 .