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RoyalTek GPS Receiver REB-2000/REB-12R REV-2000 Operational Manual
9
18 GND G Ground
19 TIMEMARK O 1PPS Time Mark
Output.
Voh
≥
VCC-0.4V, Vo1
≤
0.4V, Ioh = 4mA
Io1 = 4mA
Pulse duration 100ms. Time reference is at
the pulse negative edge. Measurements are
aligned to GPS second,
±
1 microsecond.
20 RESERVED - Reserved
VCC_5 DC Power Input
This is the main power supply for the GPS
Engine board. Use a regulated 5V supply (
±
5%) capable of supplying 180mA.
VANT
DC voltage for an active antenna. This
voltage is not required for operation with a
passive antenna.
VCC_3 DC Power Input
RoyalTek also provides the 3.3 V version
GPS receiver. This is the main power supply
for the Engine board. Use a regulated 3.3V
supply (
±
5%).
GND
GND provides the ground for the Engine
board. Connect all grounds.
Serial Data:RXA, RXB, TXA, and TXB
The GPS Engine board supports two full
duplicated serial channels. All four
connections are at TTL levels, and all
support variable baud rates. A TTL to RS232
conversion is necessary to directly
communicate with a PC serial port.
RXA
This is the main receiving channel and is
used to receive software commands to the
Engine board from user written software.
RXB
This is the auxiliary receive channel and is
used to input differential corrections to the
Engine board to DGPS navigation.
TXA
This is the main transmit channel and is used
to output navigation and measurement data
to user written software.
TXB
Reserved.
RESET
This pin provides an active-low reset input to
the Engine board. It causes the board to reset
and start searching for satellites. PB Reset is
an optional input and, if not used, should be
tied high.
TIMEMARK
This pin provides one pulse per second output from
the engine board which is synchronized to within one
microsecond of GPS time. The output is a TTL
negative level signal with negative logic.
VBAT
This is the battery backup supply that
powers the SRAM and RTC when main
power is removed. Typical current draw is 10
uA. Without an external backup battery or on
board battery, engine board will execute a
cold start after every turn on. To achieve the
faster start-up offered by a hot or warm start,
either a backup battery must be connected
or battery installed on board.