Ublox SARA-N2 Series, Руководство по системной интеграции

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SARA-N2 / N3 series - System integration manual
UBX-17005143 - R13 System description Page 21 of 95
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1.6.3 Module reset
SARA-N2 / N3 series modules can be properly reset (rebooted) by:
• AT command (see the SARA-N2 / SARA-N3 AT commands manual [4] for more details).
This command causes an “internal” or “software” reset of the module, which is an asynchronous reset
of the module baseband processor. The current parameter settings are saved in the non-volatile
memory of the module and a proper network detach is performed.
An abrupt hardware reset occurs on SARA-N2 / N3 series modules when a low level is applied on the
RESET_N input pin for a specific time period. In this case, storage of the current parameter settings
in the modul e’s non -volatile memory and a proper network detach cannot be performed.
As described in Figure 11 , the RESET_N input pin is equipped with an internal pull-up on SARA-N2 / N3
series modules, with sligthly different internal circuits.
Baseband processor
18
RESET_N
SARA-N2 series
VCC
Reset
Baseband processor
18
RESET_N
SARA-N3 series
Reset
Power management
Reset
1.1 V
Figure 11: SARA-N2 / N3 series RESET_N input equivalent circuit description
☞
It is highly recommended to avoid an abrupt hardware reset of the module by forcing a low level on
the
RESET_N input pin during module normal operation: the RESET_N line should be set low only
if reset via AT command fails or if the module does not provide a reply to a specific AT command
after a time period longer than the one defined in the SARA-N2 / N3 series AT commands
manual
[4] .
☞
Provide a test point connected to the RESET_N pin for diagnostic purpose.
1.6.4 Voltage selection of interfaces (VSEL)
☞
The digital interfaces’ voltage selection functionality is not available in SARA-N2 series modules.
The digital I/O interfaces of the SARA-N3 series modules (the UARTs, I2C, and GPIOs pins) operate at
the
V_INT voltage, which can be set to 1.8 V or 2.8 V using the VSEL input:
•
If the VSEL input pin is externally connected to GND, the digital I/O interfaces operate at 1.8 V
• If the VSEL input pin is left unconnected, the digital I/O interfaces operate at 2.8 V
The operating voltage cannot be changed dynamically: the VSEL input pin configuration has to be set
before the boot of the SARA-N3 series modules and then it cannot be changed after switched on.
☞
If the VSEL input pin is left unconnected, the VCC voltage shall be inside normal operating range
to let the digital I/O interfaces work correctly (see SARA-N3 series data sheet [2] for more details).