USGlobalsat EM-406a - Manual (Page 5)

EM-406a
Specifications are subject to be changed without notice.
Page 5 of 13
Version 1.4.1
„ Pin Assignment
„ Pin Explanation
VCC (DC power input): This is the main DC supply for a 4.5V ~ 6.5V power module board.
TX: This is the main transmit channel for outputting navigation and measurement data to user’s
navigation software or user-written software.
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”.)
GND: GND provides the ground for the engine boards. Be sure to connect all grounds
PPS: This pin provides a one pulse-per-second output from the engine board that is synchronized to
the GPS time.
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
Table B-2 GGA Data Format
Name Example Units Description
Message ID $GPGGA GGA protocol header