RGPSD012 Semtech, RGPSD012 Datasheet - Page 6

• Manufacturer Part Number: RGPSD012
• Description: KIT EVAL FOR RGPSM002
• Manufacturer: Semtech
• Type: GPSr

Specifications of RGPSD012

• For Use With/related Products: RGPSM002
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

RGPSM002
GPS Receiver
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INTERFACE DEFINITION, PRINCIPLES OF OPERATION
5.1
DATA INTERFACE
VCC – This is the main power supply
GND – This is 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 controls 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 When ON/OFF is “low”, the on/off state can be superseded with the PXEMaRT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 sentence 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 Baudrate 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 #19 to #22 in the Default
Parameters Table *, or if USPED is “high” the setting is defined by the set B #23 to #26. This setting can be modified
with the PXEMaPT manufacturer specific NMEA sentence 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 a 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 #1.
This setting can be modified with the PXEMaPS manufacturer specific NMEA sentence defined hereafter.
(*) see the Default Settings section below
1 second
~ 83 ms.
Figure 1 – PPS timing diagram
The rising edge of the PPS signal is synchronous with the GPS time.
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 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 are tested invalid or not up-to-date the output level is “low. If tested 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.
DELPOSN – Delete Initial Position pin. When set “low” for less than 1.5 seconds, this allows deleting of the initial position
in the RAM portion of the MCU and triggering re-computation of the tracking set. The position will not be deleted if GPS
fixes are already being generated. This function is useful when the initial position is known to be incorrect, for example
when the receiver is powered down, put on a plane, flown 20,000 km, and then warm-started. See timing information in
the figure below. This input pin has a pull-up resistor.
© Semtech 2005
www.semtech.com
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