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 19 of 95
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1.6.1.2 Switch-on sequence from not-powered mode
Figure 8 shows the switch-on sequence of SARA-N2 modules starting from the non-powered mode:
• The external supply is being applied to the VCC inputs, representing the start-up event.
• The RESET_N line rises suddenly to high logic level due to internal pull-up to VCC .
• Then, the V_INT generic digital interfaces supply output is enabled by the integrated PMU.
• The RXD UART data output pin also rises to the high logic level, at VCC voltage value
•
A greeting message is sent on the RXD pin (for more details see AT commands manual [4] )
• From now on the module is fully operational and the UART interface is functional
VCC
RESET_N
V_INT
HIGH when radio is ON
LOW when radio is OFF
RXD
System state OFF ON
0 s ~3.5 s
Module is
operational
Start-up
event
Greeting text
Figure 8: SARA-N2 series power-on sequence from not-powered mode
Figure 9 shows the switch on sequence of SARA-N3 modules starting from the non-powered mode:
• The external supply is being applied to the VCC inputs.
•
The PWR_ON and RESET_N lines rise suddenly to high logic level due to internal pull-up.
• Then, the PWR_ON line is set low for a proper time period, representing the start-up event.
• Then, the V_INT generic digital interfaces supply output is enabled by the integrated PMU.
• The RXD UART data output pin also rises to the high logic level, at V_INT voltage value.
• A greeting message is sent on the RXD pin (for more details, see AT commands manual [4] )
•
From now on the module is fully operational and the UART interface is functional
VCC
PWR_ON
RESET_N
V_INT
RXD
System state
OFF ON
Module is
operational
Start-up
event
Greeting text
Figure 9: SARA-N3 series power-on sequence from not-powered mode
☞
No voltage driven by an external application should be applied to the UART interface of the module
before applying the
VCC supply, to avoid latch-up of circuits and allow a proper boot of the module.
☞
No voltage driven by an external application should be applied to any generic digital interface of
the module (GPIOs, I2C interface) before the switch-on of the generic digital interface supply
source of the module (
V_INT ), to avoid latch-up of circuits and allow a proper boot of the module.