RCB-F9T - Integration manual
3.4 Predefined PIOs
In addition to the communication ports, there are some predefined PIOs provided by RCB-F9T to
interact with the receiver. These PIOs are described in this chapter.
3.4.1 RESET_N
The RCB-F9T provides the ability to reset the receiver. The RESET_N pin is an input-only pin with an
internal pull-up resistor. Driving RESET_N low for at least 100 ms will trigger a cold start.
The RESET_N pin will delete all information and trigger a cold start. It should only be used
as a recovery option.
3.4.2 TIMEPULSE
The RCB-F9T provides time pulse signals on the TIMEPULSE and TIMEPULSE 2 pins.
Shared TIMEPULSE2 and SAFEBOOT_N signals should be implemented maintaining the
possibility to pull the SAFEBOOT_N pin low in the application.
More information about the Timepulse feature, its possibility's and configuration can be
found in the chapter
3.5 Antenna supervisor
The RCB-F9T includes an active antenna supervisor that provides the means to check the antenna
for open and short circuits and to shut off the antenna supply if a short circuit is detected. Once
enabled, the active antenna supervisor produces status messages, reporting in NMEA and/or UBX
protocol.
The RCB-F9T active antenna supervisor block diagram is shown in the
The antenna supervisor is monitoring active antenna current consumption and based on that
antenna open and short circuits are detected:
• Antenna open: Current consumption 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 active 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 active antenna supervisor is enabled by default in the RCB-F9T.
3.5.1 Antenna voltage control - ANT_OFF
Enable the antenna short detection by setting the configuration item CFG-HW-
ANT_CFG_SHORTDET to true (1).
Result:
• UBX-MON-RF in u-center: Antenna status = OK. Antenna power status = ON
• ANT_OFF = active high to disable an external antenna therefore the pin is low to enable an
external antenna.
• ANT_SHORT_N = active low to detect a short therefore the pin is high (PIO pull up enabled to be
pulled low if shorted)
UBX-19003747 - R04
3 Receiver functionality
Page 18 of 54
Early production information
