USGlobalsat EB-5318RE - Manual (Page 8)

2012/8/31 8
OPERATING Description
RF_IN
This pin receives signal of GPS analog via
external active antenna. It has to be a
controlled impedance trace at 50ohm. Do not
have RF traces closed the other signal path
and routing it on the top layer. Keep the RF
traces as short as possible.
GND
This is Ground pin for the baseband circuit.
VBAT
This is the battery backup power input for the
SRAM and RTC when main power is off.
Without the external backup battery, EB-365
will always execute a cold star after turning on.
To achieve the faster start-up offered by a hot
or warm start, a battery backup must be
connected. The battery voltage should be
between 2.0V and 3.5V.
NC
EB-5318RF reserves pin, Just NC.
VCC
This is the main power supply to the engine
board. (3.1Vdc to 3.5Vdc)
RESET
Low Active, when EB-5318RF is accepted this
single, EB-5318RF going to Hibernate mode. If
want EB-5318RF up, need input ON_OFF
single.
TIMEPULSE
This pin provides one pulse-per-second output
from the board, which is synchronized to GPS
time. This is not available in Trickle Power
mode. If do not use it, Just NC.
ON_OFF
The ON_OFF pin commands the EB-5318RF
ON or OFF. There are multiple methods of
connecting this pin for different applications in
order to minimise host resource requirements.
The ON_OFF pin is used to command the
EB-5318RF to turn on or off:

The turn on command is a hardware
feature of the Power Control FSM based
on sensing a rising edge on the pin.
 The turn off command is a software
feature based on interrupts related to
rising and/or falling edges and/ or sensing
of pin levels. (Not currently supported.)
The ON_OFF pin processing is carried out by
the Power Control FSM. The ON_OFF rising
edge event during low power modes is
recorded in a status register that is
subsequently read by the processor once it is
running. When the processor is running at the
time of an ON_OFF event, the processor can
poll the status or set-up an interrupt.
WAKE_UP
System power controller, when EB-5318RF
Power ON, this pin will output 1.8V
dc
.
TXD
This is the main transmits channel for
outputting navigation and measurement data
to user’s navigation software or user written
software. Output is TTL level, 0V ~ 2.85V.
RXD
This is the main channel for receiving software
commands from SiRFdemo software or from
your proprietary software.
DR I2C Interface
The I2C host port interface supports: