EverMore GM-X205 User Manual
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
1
GM-X205
GPS Receiver Module
User’s Guide
EverMore Technology Inc.
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
2
MANUAL REVISION HISTORY
Revision Date Update Summary
Issue A April 2000 Initial release
Issue B Dec 2001 Updated NMEA output message format
© EverMore Technology Inc. All rights reserved.
Not to be reproduced in whole or part for any purpose without written permission of EverMore Technology
Inc. Information provided by EverMore Technology Inc. is believed to be accurate and reliable. However,
no responsibility is assumed by EverMore Technology Inc. for its use. EverMore Technology Inc. reserves
the right to change specification at any time without notice.
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
3
TABLE OF CONTENTS
SECTION
Table of Contents ---------------------------------------------------------3
1 Introduction -------------------------------------------------------5
1.1 Overview ---------------------------------------------------------5
1.2 Features ---------------------------------------------------------5
2 Receiver Operation -------------------------------------------------6
2.1 Receiver Specification -------------------------------------------7
3 Hardware Interface -------------------------------------------------8
3.1 Mechanical Dimensions ------------------------------------------- 8
3.2 RF Module Hardware Interface ------------------------------------ 9
3.3 Baseband Hardware Interface ------------------------------------- 10
3.4 One-Pulse-Per-Second Output --------------------------------------11
4 Software Interface -------------------------------------------------12
4.1 NMEA Output Message Specification -------------------------------12
4.1.1 NMEA Checksum Calculation -------------------------------------12
4.1.2 GGA - Global Positioning System Fix Data ----------------------13
4.1.3 GLL - Geographic Position - Latitude / Longitude --------------14
4.1.4 GSA - GNSS DOP and Active Satellites --------------------------15
4.1.5 GSV - GNSS Satellites in View ---------------------------------16
4.1.6 RMC - Recommended Minimum Specific GNSS Data ------------------17
4.1.7 VTG - Course Over Ground and Ground Speed ---------------------18
4.2 EverMore Binary Message Specification ----------------------------19
4.2.1 EverMore Binary Message 0x80: Initialization ------------------20
4.2.2 EverMore Binary Message 0x81: Data Logging -------------------- 21
4.2.3 EverMore Binary Message 0x86: Elevation Mask Input ------------21
4.2.4 EverMore Binary Message 0x87: DOP Mask Input ------------------21
4.2.5 EverMore Binary Message 0x89: Set Operating Mode --------------22
4.2.6 EverMore Binary Message 0x02: Navigation Data Output ----------23
4.2.7 EverMore Binary Message 0x04: DOP Data Output -----------------24
4.2.8 EverMore Binary Message 0x06: Channel Status Output -----------25
4.2.9 EverMore Binary Message 0x08: Measurement Data Output ---------26
4.3 Data Logging -----------------------------------------------------27
4.3.1 Data Logging Input Messages -----------------------------------28
4.3.1.1 LogConfig Set -----------------------------------------------28
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
4
4.3.1.2 LogData Dump ------------------------------------------------29
4.3.1.3 LogData Erase -----------------------------------------------29
4.3.1.4 LogConfig Read ----------------------------------------------29
4.3.2 Data Logging Output Messages ----------------------------------30
4.3.2.1 LogData -----------------------------------------------------30
4.3.2.2 LogConfig Info ----------------------------------------------30
4.3.3 Data Logging Programming Description --------------------------31
4.3.3.1 Configuring for Data Logging --------------------------------31
4.3.3.2 Retrieving Logged Data --------------------------------------31
Appendix A Supported Datum List ----------------------------------------- 32
Appendix B Default Values ----------------------------------------------- 39
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
5
SECTION 1
INTRODUCTION
1.1 OVERVIEW
The GM-X205 GPS Receiver is intended for use in a wide range of applications. The receiver
simultaneously tracks up to twelve satellites, provides accurate satellite positioning data with
fast time-to-first-fix (TTFF) and low power consumption. It is designed for high performance
and maximum flexibility in a wide range of applications including mobile asset tracking,
in-vehicle automotive guidance, location sensing, telematics and so on. The highly integrated
receiver achieves high performance, minimizes board size and power consumption
requirements. The GM-X205 is designed to withstand harsh operating environments; however,
it should be used inside an enclosure as a part of the application product designed by the
system integrator.
1.2 FEATURES
The GM-X205 GPS receiver offers following features:
l Twelve parallel tracking channels
l Fast TTFF and low power consumption
l Compact design suitable for applications requiring small space
l On-board rechargeable battery sustained real-time clock and memory for fast satellite
acquisition during power-up
l High accuracy one-pulse-per-second output
l Supports NMEA-0183 protocol
l Full navigation accuracy achievable with Standard Positioning Service
l Optimized for navigation in urban-canyon environments
l Automatic cold start with no user initialization required
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
6
SECTION 2
RECEIVER OPERATION
Upon power up, after initial self-test has completed, the GM-X205 will begin satellite
acquisition and tracking process. Under normal open-sky condition, position-fix can be
achieved within approximately 45 seconds (within 15 seconds if valid ephemeris data is
already collected from recent use). After receiver position has been calculated, valid position,
velocity and time information are transmitted through the on board serial interface.
The receiver uses the latest stored position, satellite data, and current RTC time to achieve
rapid GPS signal acquisition and fast TTFF. If the receiver is transported over a large distance
across the globe, cold-start automatic-locate sequence is invoked. The first position fix may
take up to five minutes searching the sky for the GPS signal. The acquisition performance can
be improved significantly if the host initializes the receiver with a rough estimate of time and
user position.
As soon as GPS signal is acquired and tracked, the GM-X205 will transmit valid navigation
information through its serial interface. The navigation data contains following information:
l Receiver position in latitude, longitude, and altitude
l Receiver velocity
l Time
l DOP error-magnification factor
l GPS signal tracking status
The GM-X205 will perform 3D navigation when four or more satellites are tracked. When three
or fewer satellites are tracked, altitude-hold is enabled using the last computed altitude and 2D
navigation mode is entered.
With signal blockage or rising and setting of the satellites, where a change in satellite
constellation used for position fix occurred, large position error may result. The GM-X205
incorporates a proprietary algorithm to compensate the effect of satellite constellation change,
and maintains an accurate smooth estimate of the receiver’s position, velocity, and heading.
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
7
2.1 RECEIVER SPECIFICATION
FEATURES DESCRIPTION
General
L1 frequency, C/A code, 12-channel
Sensitivity
-165 dBW minimum
Update Rate
1Hz
Accuracy
Position: 25m CEP without S/A
Velocity : 0.1/sec without S/A
Acquisition
Cold start: < 150sec (typical)
Warm start: < 45sec (typical)
Hot start: < 15sec
Reacquisition
<100msec
Dynamics
Altitude: -1000m to 18000m
Velocity: 500m/sec
Acceleration: ±4g
Operation Temperature
-20oC to +75oC
Storage Temperature
-55oC to +90oC
Operating Humidity
5% to 95%
Primary Power
+3.8V ~ 8V DC
Current Consumption
125mA @ 3.3V
Serial Interface
RS-232
Protocol
EverMore Private @ 4800/9600 baud, 8-None-1
NMEA-0183 v2.20 @ 4800/9600 baud, 8-None-1
Datum
219 standard datum, default WGS-84
Antenna
On-Board Patch Antenna
NMEA Message
GGA, GLL, GSA, GSV, RMC, and VTG
Dimension
45.5mm x 31mm x 15mm
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
8
SECTION 3
HARDWARE INTERFACE
3.1 MECHANICAL DIMENSIONS
Unit:mm
Top View
Lateral View
Bottom View
45.5± 0.2
31.0± 0.2
45.5± 0.1
4.0 9.0± 0.1
2.0
I/O Pin
I/O Pin
45.5± 0.2
31.0
CPU
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
9
3.2 RF MODULE HARDWARE INTERFACE
Pin Description
1
NC
2
NC
3
Vcc Input : 3.3V
4 CTRL : Input signal for RF module power-saving control
5 GND : Power and signal ground
6 REF Out : 16.367MHz reference output
7 GND : Power and signal ground
8 IF Out : 4.092MHz IF signal output
9 NC
10 NC
RFIC
1
2
3
4
5
6
7
8
9
10
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
10
3.3 BASEBAND HARDWARE INTERFACE
The 10 pin-connector is the same as the RF connector.
A1 : GND, Ground
A2 : 1PPS Valid Signal (1:Valid, 0:Invalid)
A3 : 1PPS
B1 : TX, Serial port output (GPS navigation output)
B2 : RX, Serial port input
B3 : Vcc, Power supply input, 3.8V ~ 8.0V DC unregulated
The following is a functional description of the pins on the 6-pin interface connector.
Pin 1. TX, Serial port output (GPS navigation output)
Pin 2. RX, Serial port input
Pin 3: Vcc, Power supply input, 3.8V ~ 8.0V DC unregulated
Pin 4: GND, Ground
Pin 5: 1PPS Valid Signal (1:Valid, 0:Invalid)
Pin 6: 1PPS
BBP1202
1
2
3
4
5
6
7
8
9
10
A3
A1
B3
B1
1
6
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
11
3.4 ONE-PULSE-PER-SECOND (1PPS) OUTPUT
The one-pulse-per-second output is provided for applications requiring precise timing
measurements. The output pulse is 1usec in duration. Rising edge of the output pulse is
accurate to +/-1usec with respect to the start of each GPS second. Accuracy of the
one-pulse-per-second output is maintained only when the GPS receiver has valid position fix.
The 1PPS output is always generated when the GPS receiver is powered-on. Proper
adjustment of the 1PPS output to align with the GPS second requires calculation of the
receiver clock offset and clock drift-rate as part of the position-velocity-time (PVT) solution.
When enough satellite signals are received to generate valid position fixes, the 1PPS output is
adjusted to align with the GPS second in several seconds. When the 1PPS output is brought in
sync with the GPS second, the 1PPS Valid Signal on the I/O pin becomes active (HIGH); when
the 1PPS output is not yet in sync with the GPS second, the 1PPS Valid Signal remains
inactive (LOW).
As long as enough satellite signals are received to generate valid position fixes, the 1PPS
output remains synchronized to the GPS second, and the 1PPS Valid Signal remains active. If
signal blockage prevents the receiver from generating valid position fix, the 1PPS output will
drift away from the GPS second and the 1PPS Valid Signal will become inactive. Upon
re-acquiring enough satellites to generate consecutive valid position fixes, the 1PPS Valid
Signal will become active again, signaling that the 1PPS output is again synchronized with the
GPS second.
For best stable operation of the 1PPS signal, it is to be operated in static environment having
clear view of the sky.
EverMore Technology Inc.
2F, No.7, R&D Road 1, Science-Based Industrial Park, Hsinchu, Taiwan, 310, R.O.C. http://www.emt.com.tw
12
SECTION 4
SOFTWARE INTERFACE
This section describes the details of the serial port commands through which the GM-X205 is
controlled and monitored. The serial port commands allow users to set the receiver
parameters, configure output message type, and retrieve status information. The baud rate
and protocol of the host COM port must match the baud rate and protocol of the GPS receiver
serial port for commands and data to be successfully transmitted and received. The default
receiver protocol is 4800baud, 8 data bits, 1 stop bit, and none parity.
4.1 NMEA OUTPUT MESSAGE SPECIFICATION
The GM-X205 supports NMEA-0183 output format as defined by the National Marine
Electronics Association (http://www.nmea.org). The currently supported NMEA messages for
GPS applications are:
GGA Global Positioning System Fix Data
GLL Geographic Position – Latitude / Longitude
GSA GNSS DOP and Active Satellites
GSV GNSS Satellites in View
RMC Recommended Minimum Specific GNSS Data
VTG Course Over Ground and Ground Speed
4.1.1 NMEA Checksum Calculation
The optional NMEA checksum can be enabled or disabled when setting up the NMEA protocol.
The checksum consists of a “*” and two hexidecimal digits derived by exclusive-OR of all the
characters between, but not inlcuding, the “$” and “*” characters.
Loading...