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Pin Explanation
VCC
: (DC power input) This is the main DC supply for a 3.8V ~ 6.5V power module board.
VBAT:
This is the battery backup input that powers the SRAM and RTC when main power is removed.
Typical current draw is 10uA. Without an external backup battery, the module/engine board will execute a
cold star after every turn on. To achieve the faster start-up offered by a hot or warm start, a battery
backup must be connected. To maximize battery lifetime, the battery voltage should be between 2.5v and
3.6v.
PBRES:
(Push Button Reset) This pin provides an active-low reset input to the engine board. It causes
the engine board to reset and start searching for satellites.
SELECT:
Do not connect (do not use)
TX:
This is the main transmit channel for outputting navigation and measurement data to user's
navigation software or user-written software. Output TTL level, 0V ~ 2.85V
RX:
This is the main receive channel for receiving software commands to the engine board from
SiRfdemo software or from user-written software. (NOTE: When not in use this pin must be kept "HIGH"
for operation. From Vcc connect a 470 Ohm resistor in series with a 3.2v Zener diode to Ground. Then,
connect the Rx input to Zener's cathode to pull the input "HIGH".)
TIME MARK (1PPS):
synchronized to GPS time
GND:
GND provides the ground for the engine boards. Be sure to connect all grounds
Mounting
Recommended mounting methods:
a.
Use industrial grade double-sided foam tape. Place it on the bottom side of the engine board.
b.
A recessed cavity in your housing design with a foam pad to eliminate shifting or movement.
c.
Use provided mounting holes on the GPS engine board PCB.
3. Software Commands
NMEA Output Command
GGA-Global Positioning System Fixed Data
Table B-2 contains the values for the following example:
$GPGGA,161229.487,3723.2475,N,12158.3416,W,1,07,1.0,9.0,M,,,,0000*18
This pin provides one pulse-per-second output from the engine board that is
ET-332
Specifications are subject to be changed without notice.
Page 6 of 15
Version 1.3.1
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