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The TIMEPULSE2 and the SAFEBOOT_N functions share the same PIO pin via series
resistors, hence the TIMEPULSE2 pin should not be pulled low or high at reset or start up in
the application circuit, otherwise this can provoke or inhibit safeboot operation.
3.7 Antenna supervisor
The RCB-F9T includes circuitry to check an active antenna connection for open and short circuits
and to shut off the antenna supply if a short circuit is detected. The circuitry connects with the
three antenna supervison pins on the ZED-F9T module: ANT_OFF, ANT_SHORT_N and ANT_DET
as shown in
Figure
messages, reporting in NMEA and/or UBX protocol.
The antenna supervisor monitors the antenna supply current consumption for open or short circuit
conditions:
• Antenna open: current consumption is less than 16 mA (typical value)
• Antenna short circuit: current consumption is more than 215 mA (typical value)
The antenna supervisor can be configured through the CFG-HW-ANT_* configuration items. The
current configuration of the antenna supervisor can also be checked by polling the related CFG-
HW_ANT_* configuration items.
The current active antenna status can be determined by polling the UBX-MON-RF message. If an
antenna is connected, the initial state after power-up is "Active Antenna OK" in the u-center UBX-
MON-RF view.
The antenna supervisor functionality is enabled by default in the RCB-F9T.
The following sections describes the three pin functions.
3.7.1 Antenna supply control - ANT_OFF
Setting the configuration item CFG-HW-ANT_CFG_VOLTCTRL to '1' enables the antenna supply On/
Off control.
The antenna voltage control is enabled by default in the RCB-F9T.
When enabled:
• ANT_OFF output controls the external antenna supply (active low).
• Polling
UBX-MON-RF : Antenna status = OK, Antenna power status = ON
Start-up message at power up if configuration is stored:-
$GNTXT,01,01,02,ANTSUPERV=AC SD *37
$GNTXT,01,01,02,ANTSTATUS=INIT*3B
$GNTXT,01,01,02,ANTSTATUS=OK*25
ANTSUPERV=AC SD - (Antenna controlled and short detection activated - see below)
3.7.2 Antenna short detection - ANT_SHORT_N
Setting the configuration item CFG-HW-ANT_CFG_SHORTDET to true (1) enables the antenna
short detection function.
Antenna short detection is enabled by default in the RCB-F9T.
UBX-22004121 - R01
C1-Public
1. Once enabled, the receiver antenna supervisor function produces status
3 Receiver functionality
Early production information
RCB-F9T - Integration manual
Page 27 of 64
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