Global Sat ET-318 User manual

ET-318
Specifications are subject to be changed without notice.
Page 1 of 16
Version 1.3.1
GPS Engine Board
ET-318
Globalsat Technology Corporation
16F., No. 186, Jian-Yi Road, Chung-Ho City, Taipei Hsien 235, Taiwan
Tel: [phone]/ Fax: [phone]
[e-mail]
www.globalsat.com.tw
USGlobalSat, Inc.
14740 Yorba Court, Chino, CA 91710
Tel: [phone] / Fax: [phone]
[e-mail]
www.usglobalsat.com

ET-318
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Version 1.3.1
Product Information
Product Part I.D. ET-318
Product Description: SMT GPS Board
Product Features:
9SiRF StarIII/FLP chipset
9Very high sensitivity (Tracking Sensitivity: -159 dBm)
920 channels
9Extremely fast TTFF (Time To First Fix) at low signal levels
9Compact size
9One size component, easy to mount on another PCB board
9Support NMEA 0183 and SiRF binary protocol
Product Specifications
GPS Receiver
Chipset SiRF StarIII/FLP
Frequency L1, 1575.42 MHz
Code 1.023 MHz chip rate
Protocol NMEA 0183
Default: GGA, GSA, GSV, RMC, VTG, GLL
SiRF binary and NMEA Command
Available Baud Rate 4,800 to 57,600 bps adjustable
Channels 20
Sensitivity -159dBm
Cold Start 42 seconds average
Warm Start 38 seconds average
Hot Start 1 second average
Reacquisition 0.1 second average
Accuracy Position: 10 meters, 2D RMS
5 meters, 2D RMS, WAAS enabled

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Version 1.3.1
Velocity: 0.1 m/s
Time: 1us synchronized to GPS time
Maximum Altitude 18,000 meter
Maximum Velocity 515 meter/second
Maximum Acceleration 4G
Jerk 20m/sec **3
Datum WGS-84 Default
Interface
I/O Connector Type
External Antenna Port
Physical Characteristic
Dimensions 0.6” x 0.55” x 0.11” (15.2 x 14 x 2.8 mm)
DC Characteristics
Power Supply 3.3V ±5% DC Input
Power Consumption 42mA (Continuous Mode)
25mA (Trickle Mode)
Environmental Range
Humidity Range 5% to 95% non-condensing
Operation Temperature -40C to 85C
Storage Temperature -40C to 85C
Recommended GPS Active/Passive Antenna Specifications
Frequency: 1575.42+2 MHz
Axial Ratio: 3 dB Typical
Output Impedance: 50Ω
Polarization: RHCP
Output VSWR: 1.5 Max.
Active Option: Low Noise Amplifier
Amplifier Gain: 20~26dB Typical
Output VSWR: 2.0 Max.
Noise Figure: 2.0 dB Max.

ET-318
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Version 1.3.1
2. Technical Information
Pin Assignment
Pin Signal Name I/O Description
1 GND G Analog Ground
2 RF_IN RF GPS Signal input
3 GND G Analog Ground
4 NRESET I Reset (Active low)
5 VCC_IN PWR DC Supply Voltage input
6 VBAT PWR Backup voltage supply
7 RXB I Serial port B
8 TXB O Serial port B
9 GND G Analog Ground
10 BOOTSEL Boot mode
11 TXA O Serial port A
12 RXA I Serial port A
13 GPIO1 I General –purpose I/O
14 GPIO14 I General –purpose I/O
15 TIMEMARK O One pulse per second
16 GPIO13 I General –purpose I/O
17 GPIO15 I General –purpose I/O
ET-318-01 Bottom View

ET-318
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Version 1.3.1
Pin Explanation
VCC_IN
This is the main DC supply for a 3.3V +- 5% DC input power module board.
GND
GND provides the ground for digital part.
BOOTSEL
Set this pin to high for programming flash.
RXA
This is the main receiver channel and is used to receive software commands to the board from SIRFdemo
software or from user written software. Pull up if not used.
RXB
This is the auxiliary receiving channel and is used to input differential corrections to the board to enable
DGPS navigation. Pull up if not used.
TXA
This is the main transmitting channel and is used to output navigation and measurement data to
SiRFdemo or user written software.
TXB
For user’s application (not currently used).
RF_IN
This pin receiver signal of GPS analog .due to the RF characteristics of the signal the design has to certain
criteria. The line on the PCB from the antenna (or antenna connector) has to be a controlled microstrip line
at 50Ω.
PPS
This pin provides one pulse-per-second output from the board, which is synchronized to GPS time. This is
not available in Trickle Power mode.
VBAT (memory Back-up)
This is the battery backup input that powers the SRAM and RTC when main power is removed. Typical
current draw is 15uA. 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. The battery voltage should be between 2.0v and 5.0v. (NOTE: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 VBAT input to
Zener’s cathode to pull the input “HIGH”.)
TIMEMARK
This pin provides one pulse-per-second output from the board, which is synchronized to GPS time. This is
not available in Trickle Power mode.

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Version 1.3.1
GPIO Functions
Several I/Os are connected to the digital interface connector for custom applications.
Application Circuit
R46
560R
1 2
C1
1U
1 2
TXA
RXB
RESET
BATTER Y
GPIO15
50 ohm microstrip line
GPIO13
RXA
R5
SAW FILTER
1 2
U1 GPS
6
5
4
3
2
1
7
8
9
10
11
12
13
14
15
17
16
VBAT
VCC_IN
NRESET
GND
RF_IN
GND
RXB
TXB
GND
BOOTSEL
TXA
RXA
GPIO1
GPIO14
TIMEMARK
GPIO15
GPIO13
GPIO1
3.3V
GPIO14
Antenna
1.
RB715F
3
1
2
BOOTSEL
TXB
C2
0.1U
1 2
option
VCC_RF
TIMEMARK
LNA
21 ..
Recommended Layout PAD

ET-318
Specifications are subject to be changed without notice.
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Version 1.3.1
Mechanical Layout

ET-318
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Version 1.3.1
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
UTC Time 161229.487 hhmmss.sss
Latitude 3723.2475 ddmm.mmmm
N/S Indicator N N=north or S=south
Longitude 12158.3416 dddmm.mmmm
E/W Indicator W E=east or W=west
Position Fix Indicator 1 See Table B-3
Satellites Used 07 Range 0 to 12
HDOP 1.0 Horizontal Dilution of Precision
MSL Altitude19.0 meters
Units M meters
Geoid Separation1meters
Units M meters
Age of Diff. Corr. second Null fields when DGPS is not used
Diff. Ref. Station ID 0000
Checksum *18
<CR><LF> End of message termination
SiRF Technology Inc. does not support geoid corrections. Values are WGS84 ellipsoid heights.
Table B-3 Position Fix Indicator
Value Description
0 Fix not available or invalid
1 GPS SPS Mode, fix valid
2 Differential GPS, SPS Mode , fix valid
3 GPS PPS Mode, fix valid

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Version 1.3.1
GLL-Geographic Position-Latitude/Longitude
Table B-4 contains the values for the following example:
$GPGLL,3723.2475,N,12158.3416,W,161229.487,A*2C
Table B-4 GLL Data Format
Name Example Units Description
Message ID $GPGLL GLL protocol header
Latitude 3723.2475 ddmm.mmmm
N/S Indicator n N=north or S=south
Longitude 12158.3416 dddmm.mmmm
E/W Indicator W E=east or W=west
UTC Position 161229.487 hhmmss.sss
Status A A=data valid or V=data not valid
Checksum *2C
<CR><LF> End of message termination
GSA-GNSS DOP and Active Satellites
Table B-5 contains the values for the following example:
$GPGSA,A,3,07,02,26,27,09,04,15,,,,,,1.8,1.0,1.5*33
TableB-5GSADataFormat
Name Example Units Description
Message ID $GPGSA GSA protocol header
Mode1 A See Table B-6
Mode2 3 See Table B-7
Satellite Used107 Sv on Channel 1
Satellite Used102 Sv on Channel 2
.
Satellite Used1Sv on Channel 12
PDOP 1.8 Position dilution of Precision
HDOP 1.0 Horizontal dilution of Precision
VDOP 1.5 Vertical dilution of Precision
Checksum *33
<CR><LF> End of message termination
1. Satellite used in solution.

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Version 1.3.1
TableB-6Mode1
Value Description
M Manual-forced to operate in 2D or 3D mode
A 2D automatic-allowed to automatically switch 2D/3D
TableB-7Mode2
Value Description
1 Fix Not Available
2 2D
3 3D
GSV-GNSS Satellites in View
Table B-8 contains the values for the following example:
$GPGSV,2,1,07,07,79,048,42,02,51,062,43,26,36,256,42,27,27,138,42*71
$GPGSV,2,2,07,09,23,313,42,04,19,159,41,15,12,041,42*41
TableB-8GSVDataFormat
Name Example Units Description
Message ID $GPGSV GSV protocol header
Number of Messages12 Range 1 to 3
Message Number11 Range 1 to 3
Satellites in View 07
Satellite ID 07 Channel 1(Range 1 to 32)
Elevation 79 degrees Channel 1(Maximum90)
Azimuth 048 degrees Channel 1(True, Range 0 to 3
5
SNR(C/No) 42 dBHz Range 0 to 99,null when not tr
a
……. …….
Satellite ID 27 Channel 4 (Range 1 to 32)
Elevation 27 Degrees Channel 4(Maximum90)
Azimuth 138 Degrees Channel 4(True, Range 0 to 3
5
SNR(C/No) 42 dBHz Range 0 to 99,null when not tr
a
Checksum *71
<CR><LF> End of message termination
Depending on the number of satellites tracked multiple messages of GSV data may be required.

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Version 1.3.1
RMC-Recommended Minimum Specific GNSS Data
Table B-9 contains the values for the following example:
$GPRMC,161229.487,A,3723.2475,N,12158.3416,W,0.13,309.62,120598,,*10
Table B-9 RMC Data Format
Name Example Units Description
Message ID $GPRMC RMC protocol header
UTC Time 161229.487 hhmmss.sss
Status A A=data valid or V=data not valid
Latitude 3723.2475 ddmm.mmmm
N/S Indicator N N=north or S=south
Longitude 12158.3416 dddmm.mmmm
E/W Indicator W E=east or W=west
Speed Over Ground 0.13 knots
Course Over Ground 309.62 degrees True
Date 120598 ddmmyy
Magnetic Variation2degrees E=east or W=west
Checksum *10
<CR><LF> End of message termination
SiRF Technology Inc. does not support magnetic declination. All “course over ground” data are
Geodetic WGS48 directions.
VTG-Course Over Ground and Ground Speed
$GPVTG,309.62,T,,M,0.13,N,0.2,K*6E
Table B-9 VTG Data Format
Name Example Units Description
Message ID $GPVTG VTG protocol header
Course 309.62 degrees Measured heading
Reference T True
Course degrees Measured heading
Reference M Magnetic
Speed 0.13 knots Measured horizontal speed
Units N Knots
Speed 0.2 Km/hr Measured horizontal speed
Units K Kilometers per hour
Checksum *6E
<CR><LF> End of message termination

ET-318
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Version 1.3.1
■NMEA Input Command
A.) Set Serial Port ID:100 Set PORTA parameters and protocol
This command message is used to set the protocol (SiRF Binary, NMEA, or USER1) and/or the
communication parameters (baud, data bits, stop bits, parity). Generally, this command is utilize to
switch the GPS module back to SiRF Binary protocol mode, where an extensive message commands
are readily available. In example, whenever users are interested in altering navigation parameters, a
valid message sent and is receive by the recipient module, the new parameters will be stored in
battery backed SRAM and then the receiver will restart using the saved parameters.
Format:
$PSRF100,<protocol>,<baud>,<DataBits>,<StopBits>,<Parity>*CKSUM
<CR><LF>
<protocol> 0=SiRF Binary, 1=NMEA, 4=USER1
<baud> 1200, 2400, 4800, 9600, 19200, 38400
<DataBits> 8,7. Note that SiRF protocol is only valid f8 Data bits
<StopBits> 0,1
<Parity> 0=None, 1=Odd, 2=Even
Example 1: Switch to SiRF Binary protocol at 9600,8,N,1
$PSRF100,0,9600,8,1,0*0C<CR><LF>
Example 2: Switch to User1 protocol at 38400,8,N,1
$PSRF100,4,38400,8,1,0*38<CR><LF>
**Checksum Field: The absolute value calculated by exclusive-OR the 8 data bits of each character
in the Sentence, between, but, excluding “$” and “*”. The hexadecimal value of the most significant
and least significant 4 bits of the result are converted to two ASCII characters (0-9,A-F) for
transmission. First, the most significant character is transmitted.
**<CR><LF> : Hex 0D 0A
B.) Navigation initialization ID:101 Parameters required for start
This command is used to initialize the GPS module for a “Warm” start, by providing real-time position
（in X, Y, Z coordinates), clock offset, and time. This action enables the GPS receiver to search for the
necessary satellite signals at the correct signal parameters. The newly acquired and stored satellite
data will enable the receiver to acquire signals more quickly, and thus, generate a rapid navigational
solution.
When a valid Navigation Initialization command is receive, the receiver will restart using the input
parameters as a basis for satellite selection and acquisition.
Format
$PSRF101,<X>,<Y>,<Z>,<ClkOffset>,<TimeOfWeek>,<WeekNo>,<chnlCount>,<ResetCfg>
*CKSUM<CR><LF>
<X> X coordinate position
INT32

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Version 1.3.1
<Y> Y coordinate position
INT32
<Z> Z coordinate position
INT32
<ClkOffset> Clock offset of the receiver in Hz, Use 0 for last saved value if available.
If this is unavailable, a default value of 75000 for GSP1, 95000 for GSP 1/LX
is used.
INT32
<TimeOf Week> GPS Time Of Week
UINT32
<WeekNo> GPSWeekNumber
UINT16
Week No and Time Of Week calculation from UTC time
<chnlCount> Number of channels to use.1-12. If your CPU throughput is not high enough,
you could decrease needed throughput by reducing the number of active
channels
UBYTE
<ResetCfg> bitmask
0×01=Data Valid warm/hotstarts=1
0×02=clear ephemeris warm start=1
0×04=clearmemory.Coldstart=1
UBYTE
Example: Start using known position and time.
$PSRF101,-2686700,-4304200,3851624,96000,497260,921,12,3*7F
C.) Set DGPS Port ID:102 Set PORT B parameters for DGPS input
This command is used to control Serial Port B, an input serial only port used to receive RTCM
differential corrections. Differential receivers may output corrections using different communication
parameters. The default communication parameters for PORT B are set for 9600 Baud, 8data bits, 0
stop bits, and no parity. If a DGPS receiver is used which has different communication parameters,
use this command to allow the receiver decode data correctly. When a valid message is received, the
parameters are stored in a battery backed SRAM. Resulting, GPS receiver using the saved
Parameters for restart.
Format:
$PSRF102,<Baud>,<DataBits>,<StopBits>,<Parity>*CKSUM<CR><LF>
<baud> 1200,2400,4800,9600,19200,38400
<DataBits> 8
<StopBits> 0,1
<Parity> 0=None,Odd=1,Even=2
Example: Set DGPS Port to be 9600,8,N,1
$PSRF102,9600,8,1.0*12
D.) Query/Rate Control ID:103 Query standard NMEA message and/or set output rate

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Version 1.3.1
This command is used to control standard NMEA data output messages: GGA, GLL, GSA, GSV, RMC,
and VTG. Using this command message, standard NMEA message is polled once, or setup for
periodic output. In addition, checksums may also be enable or disable contingent on receiving
program requirements. NMEA message settings are stored in a battery-backed memory for each entry
when the message is accepted.
Format:
$PSRF103,<msg>,<mode>,<rate>,<cksumEnable>*CKSUM<CR><LF>
<msg> 0=GGA,1=GLL,2=GSA,3=GSV,4=RMC,5=VTG
<mode> 0=SetRate,1=Query
<rate> Output every <rate>seconds, off=0,max=255
<cksumEnable> 0=disable Checksum,1=Enable checksum for specified message
Example 1: Query the GGA message with checksum enabled
$PSRF103,00,01,00,01*25
Example 2: Enable VTG message for a 1Hz constant output with checksum enabled
$PSRF103,05,00,01,01*20
Example 3: Disable VTG message
$PSRF103,05,00,00,01*21
E.) LLA Navigation initialization ID:104 Parameters required to start using Lat/Lon/Alt
This command is used to initialize the GPS module for a “Warm” start, providing real-time position
(Latitude, Longitude, Altitude coordinates), clock offset, and time. This action enables the GPS
receiver to search for the necessary satellite signals at the correct signal parameters. The newly
acquired and stored satellite data will enable the receiver to acquire signals more quickly, and thus,
generate a rapid navigational solution.
When a valid LLA Navigation Initialization command is receive, then the receiver will restart using the
input parameters as a basis for satellite selection and acquisition.
Format:
$PSRF104,<Lat>,<Lon>,<Alt>,<ClkOffset>,<TimeOfWeek>,<WeekNo>,
<ChannelCount>, <ResetCfg>*CKSUM<CR><LF>
<Lat> Latitude position, assumed positive north of equator and negative
south of equator float, possibly signed
<Lon> Longitude position, it is assumed positive east of Greenwich
and negative west of Greenwich Float, possibly signed
<Alt> Altitude position float, possibly signed
<ClkOffset> Clock Offset of the receiver in Hz, use 0 for last saved value if
available.

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Version 1.3.1
If this is unavailable, a default value of 75000 for GSP1, 95000 for GSP1/LX
is used.
INT32
<TimeOfWeek> GPS Time Of Week
UINT32
<WeekNo> GPSWeekNumber
UINT16
<ChannelCount> Number of channels to use. 1-12
UBYTE
<ResetCfg> bit mask
0×01=Data Valid warm/hot starts=1
0×02=clear ephemeris warm start=1
0×04=clearmemory.Coldstart=1
UBYTE
Example: Start using known position and time.
$PSRF104,37.3875111,-121.97232,0,96000,237759,922,12,3*37
F.) Development Data On/Off ID:105 Switch Development Data Messages On/Off
Use this command to enable development debug information if you are having trouble in attaining
commands accepted. Invalid commands will generate debug information that should enable the user
to determine the source of the command rejection. Common input rejection problems are associated
to invalid checksum or parameter out of specified range. Note, this setting is not preserved across a
module reset.
Format: $PSRF105,<debug>*CKSUM<CR><LF>
<debug> 0=Off,1=On
Example: Debug On $PSRF105,1*3E
Example: Debug Off $PSRF105,0*3F
G). Select Datum ID:106 Selection of datum to be used for coordinate transformations
GPS receivers perform initial position and velocity calculations using an earth-centered earth-fixed
(ECEF) coordinate system. Results may be converted to an earth model (geoid) defined by the
selected datum. The default datum is WGS 84 (World Geodetic System 1984) which provides a
worldwide common grid system that may be translated into local coordinate systems or map Datum.
(Local map Datum are a best fit to the local shape of the earth and not valid worldwide.)
Examples:
Datum select TOKYO_MEAN
$PSRF106,178*32
Name Example Units Description
Message ID $PSRF106 PSRF106 protocol header
Datum 178 21= WGS84
178= Tokyo_Mean
179= Tokyo_Japan
180= Tokyo_Korea

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Version 1.3.1
181= Tpkyo_Okinawa
Checksum *32
<CR><LF> End of message termination
* * *