EVA-7M - Hardware Integration Manual
UBX-12003235 - R05
Production Information
Design-in
Page 11 of 42
2.3
I/O Pins
All I/O pins make use of internal pull-ups. Thus, there is no need to connect unused pins to
VCC_IO
.
2.3.1
Time pulse
A configurable time pulse signal is available and configured by default to 1 pulse per second. For further
information see the
u-blox 7 Receiver Description including Protocol Specification
2.3.2
External interrupt
EXTINT
is an external interrupt pin with fixed input voltage thresholds with respect to
VCC_IO
(see the
EVA-7M
[1] for more information). It can be used for wake-up functions in Power Save Mode on all u-blox 7
modules and for aiding. Leave open if unused; its function is disabled by default. By default the external
interrupt is disabled.
For further information see the
u-blox 7 Receiver Description including Protocol Specification
If the EXTINT is configured for on/off switching of the EVA-7M, 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
EVA-7M supports 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 18) provides antenna supply short circuit detection. It will
prevent antenna operation via transistor T1 if a short circuit has been detected or if it
i
s not required (e.g. in
Power Save Mode).
The status of the active antenna can be checked by the UBX-MON-HW message. See the
u-blox 7 Receiver
Description including Protocol Specification
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.
2.3.3.2
3-pin antenna supervisor
The 3-pin antenna supervisor is comprised of the
ANT_DET
(active antenna detection),
ANT_SHORT_N
(short
detection) and
ANT_OFF
(antenna on/off control) pins. This function must be activated by sending the following
sequence to the EVA-7M receiver in production:
B5 62 06 41 0C 00 00 00 03 1F CD 1A 38 57 FF FF F6 FF DE 11
Applying this sequence results in a permanent change and cannot be reversed.
