EVA-8M and EVA-M8 series - Hardware Integration Manual
UBX-16010593 - R06
Design-in
Page 13 of 47
Early Production Information
By default, the time pulse signal is disabled. For more information, see the
u-blox 8 / u-blox M8
Receiver Description Including Protocol Specification [3].
2.3.2
External interrupt
EXTINT
is an external interrupt pin with fixed input voltage thresholds with respect to
VCC_IO
(see
the
EVA-M8 Data Sheet [1] and the EVA-8M Data Sheet [2] for more information). It can be used for
wake-up functions in Power Save Mode on all u-blox M8 modules and for aiding. Leave open if unused;
its function is disabled by default. By default, the external interrupt is disabled.
If the
EXTINT
is not used for an external interrupt function, it can be used for some other purpose.
E.g. as an output pin for the TXD Ready feature to indicate that the receiver has data to transmit.
For further information, see the pin assignment in section 2.9 and the u-blox 8 / u-blox M8 Receiver
Description Including Protocol Specification [3].
☞
If the
EXTINT
is configured for on/off switching of the EVA-8M / EVA-M8 series GNSS modules,
the internal pull-up becomes disabled. Thus make sure the
EXTINT
input is always driven within
the defined voltage level by the host.
2.3.3
Active antenna supervisor
The EVA-8M / EVA-M8 series GNSS modules support active antenna supervisors. The antenna
supervisor gives information about the status of the active antenna and will turn off the supply to the
active antenna in case a short is detected or to optimize the power consumption when in Power Save
Mode.
There is either a 2-pin or a 3-pin antenna supervisor. By default the 2-pin antenna supervisor is
enabled.
2.3.3.1
2-pin antenna supervisor
The 2-pin antenna supervisor function, which is enabled by default, consists of the
ANT_OK
input and
the
ANT_OFF
output pins.
Function
I/O
Description
Remarks
ANT_OK
I
Antenna OK
“high” = Antenna OK
“low” = Antenna not OK
Default configuration
ANT_OFF
O
Control signal to turn on and off the antenna supply
“high” = Antenna OFF
“low” = Antenna ON
Default configuration
Table 3: 2-pin antenna supervisor pins
The circuitry, as shown in Appendix A.7 (see Figure 19) provides antenna supply short circuit
detection. It will prevent antenna operation via transistor T1 if a short circuit has been detected or if
it is not required (e.g. in Power Save Mode).
The status of the active antenna can be checked by the UBX-MON-HW message. For more
information, see the
u-blox 8 / u-blox M8 Receiver Description Including Protocol Specification [3].
Open drain buffers U4 and U7 (e.g. Fairchild NC7WZ07) are needed to shift the voltage levels. R3 is
required as a passive pull-up to control T1 because U4 has an open drain output. R4 serves as a
current limiter in the event of a short circuit.
