GPSM001
OEM GPS Receiver Module
INTERFACE DEFINITION, PRINCIPLES OF OPERATION
DATA INTERFACE
VCC – This the main power supply
GND – This the power and signal ground
VRTCBK – This is the back-up supply for the on-board hardware Real Time Clock
All I/Os on the Data Interface are related to VCC and GND levels.
ON/OFF - The ON/OFF input pin control whether the GPS engine is turned ON or OFF. If this pin is “high” whenever a
reset condition occurs or if it is turned “high” when in operation, then the GPS engine is turned on. If this pin is “low”
whenever a reset condition occurs then the GPS engine is not started. If this pin is turned “low” when in operation then
the GPS engine is turned off. When ON/OFF is “low”, the on/off state can be superseded with the PXEMaRT
manufacturer specific NMEA command on RXA, as defined hereafter. This input pin has a pull-up resistor.
RXA – Serial Receive data. This input pin has a pull-up resistor.
TXA – Serial Transmit data
USPED – Hardware Baud rate selection
The Serial NMEA data port (lines RXA and TXA) is an asynchronous serial port (UART). Upon reset, if the USPED input
pin is “low” the setting for this port is defined by the set A of UART parameters #1 to 4 in the Default Parameters Table
*, or if USPED is “high” the setting is defined by the set B. This setting can be modified with the PXEMaPT manufacturer
specific NMEA command defined hereafter. This input pin has a pull-up resistor. There is no flow control on the UART.
(*) see the Default Settings section below
PPS - The PPS output pin is Pulse Per Second highly accurate timing signal generated by the on-board GPS baseband
processor. The PPS signal is available only when the receiver does position fixes. Otherwise its output level is “low”.
After a reset condition, the setting for this port is defined in the Default Parameters Table *, parameter #12. This setting
can be modified with the PXEMaPS manufacturer specific NMEA command defined hereafter.
(*) see the Default Settings section below
1 second
~ 83 ms.
RESETN – Manual Reset input pin. The receiver has 2 reset conditions: first, on power-on, thanks to an on-board
Power On Reset circuitry; and second an external reset when the RESETN pin is “low”. This input pin has a pull-up
resistor.
ALMRDY – When in Active mode, this output indicates the on-board Almanac status. Upon start up and whenever the
Almanac data is tested invalid or not up-to-date the output level is “low. If test is valid and up-to-date the output level is
“high”.
STANDBYN – This input sets the receiver in Stand-by mode when its level is “low”. Otherwise the receiver is either in
Active or Power Save modes. See below, under Operating modes for details. This input pin has a pull-up resistor.
DS031-2 Jan ‘04
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