Global Sat ET-312 User manual

ET-312
Page1of21
Version 1.4
GPS Engine Board ET-312
Version 1.4
01/20/2010
Globalsat Technology Corporation Headquarters (Far East Century Park)
16F., No. 186, Jian-Yi Road, Chung-Ho City, Taipei Hsien 235, Taiwan
Tel: [phone]/ Fax: [phone]
E-mail : [e-mail]
Website: www.globalsat.com.tw

ET-312
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
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Version 1.4
1. Product Information
Product Name: ET-312
Product Description:
ET-312 is a compact, high performance, and low power consumption GPS engine board. It uses SiRF
Star III chipset which can track up to 20 satellites at a time and perform fast TTFF in weak signal
environments. ET-312 is suitable for the following applications:
‧ Automotive navigation
‧ Personal positioning
‧ Fleet management
‧ Mobile phone navigation
‧ Marine navigation
Product Features:
SiRF star III high performance GPS Chipset
Very high sensitivity (Tracking Sensitivity: -159 dBm)
Extremely fast TTFF (Time To First Fix) at low signal level
One serial ports
4Mb flash
Built-in LNA
Compact size (28mm * 20 mm * 2.9mm) suitable for space-sensitive application
One size component, easy to mount on another PCB board
Support NMEA 0183 and SiRF binary protocol
Product Specifications
GPS Receiver
Chipset SiRF GSC3f/LP
Frequency L1, 1575.42 MHz
Code C/A Code
Protocol NMEA 0183 v2.2
Default:GGA,GSA,GSV,RMC
Support:VTG,GLL,ZDA)
SiRF binary and NMEA Command
Available Baud Rate 4,800 to 57,600 bps adjustable

ET-312
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Version 1.4
Channels 20
Flash 4Mbit
Sensitivity Tracking:-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
Velocity: 0.1 m/s
Time: 1us synchronized to GPS time
Maximum Altitude ＜18,000 meter
Maximum Velocity ＜515 meter/second
Maximum Acceleration ＜4G
Update Rate 1 Hz
DGPS WAAS, EGNOS, MSAS
Datum WGS-84
Interface
I/O Pins 1 serial ports
Physical Characteristic
Type 13-pin stamp holes
Dimensions 28 mm * 20 mm * 2.9 mm
DC Characteristics
Power Supply 3.3Vdc ± 5%
Backup Voltage 2.0 ~ 3.6Vdc ± 10%
Power Consumption Acquisition: 60mA
Tracking: 42mA
Environmental Range
Humidity Range 5% to 95% non-condensing
Operation Temperature -30℃ to 85℃
Storage Temperature -40℃ to 85℃

ET-312
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
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Version 1.4
2. Technical Information
Block Diagram
Module Pin Assignment:
M1
GPS Engine Board
5
6
7
11
12
13
1
2
3
4
8
9
10
GND
GND
VIN
RX
GND
GND
GND
RF
GND
GND
BATTERY
GPIO1
TX
Pin NO. Pin Name Remark
1. GND Ground.
2. RF Connect to External Active Antenna. While external antenna is used, the
optional power is needed.
3. GND Ground.
4. GND Ground.
5. GND Ground.
6. GND Ground.
7. VIN This is the main DC supply for a 3.3V +- 5% DC input power module board.
8. BATTERY 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

ET-312
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Version 1.4
5.0v.
9. GPIO1 User can use this I/O pin for special function.For example, on/off LED
10. TX This is the main transmits channel for outputting navigation and
measurement data to user’s navigation software or user written
software.Output TTL level, 0V ~ 2.85V
11. RX This is the main receive channel for receiving software commands to the
engine board from SiRFdemo software or from user written software.
12. GND Ground.
13. GND Ground.

ET-312
The Specifications are subject to be changed without notice. Copyright ©2007, GlobalSat Technology.
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Version 1.4
Application Circuit
GPS Active Antenna Specification(Recommendation)
Frequency: 1575.42+2 MHz
Axial Ratio: 3 dB Typical
output Impedance: 50Ω
Polarization: RHCP
Amplifier Gain :18~22dB Typical
Output VSWR: 2.0 Max.
Noise Figure: 2.0 dB Max

ET-312
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Version 1.4
Dimensions

ET-312
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Version 1.4
Recommend Layout PAD

ET-312
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Version 1.4
Recommended Reflow Profile:
Pre heating temperature: 150±10[ ]℃Pre heating time: 90±30[sec.]
Heating temperature: 235±5[ ]℃Heating time: 10±1[sec.]
Peak temperature must not exceed 240 and the duration of ove℃r 200 should be 30±10℃
Seconds.
10±1s
240℃Max.
30±10s
200℃
150±10℃
90±30s
235±5℃.
Temperature [℃]
Time [sec.]

ET-312
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Version 1.4
SOFTWARE COMMAND
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 Exam
p
le Units Descri
p
tio
n
Messa
g
e ID $GPGGA GGA
p
rotocol heade
r
UTC Time 161229.487 hhmmss.sss
Latitude 3723.2475 ddmm.mmmm
N
/S Indicato
r
N
N
=north or S=south
Lon
g
itude 12158.3416 dddmm.mmm
m
E/W Indicato
r
W E=east or W=wes
t
Position Fix Indicato
r
1 See Table B-3
Satellites Use
d
07 Ran
g
e 0 to 12
HDOP 1.0 Horizontal Dilution of Precision
MSL Altitude19.0 meters
Units M meters
Geoid Se
p
aration1meters
Units M meters
A
g
e of Diff. Corr. second
N
ull fields when DGPS is not used
Diff. Ref. Station ID 0000
Checksu
m
*18
<CR><LF> End of messa
g
e termination
SiRF Technology Inc. does not support geoid corrections. Values are WGS84 ellipsoid heights.
Table B-3 Position Fix Indicator
Va l u e D e s c r i
p
tion
0 Fix not available or invali
d
1 GPS SPS Mode, fix vali
d
2 Differential GPS, SPS Mode , fix vali
d
3 GPS PPS Mode, fix vali
d
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

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Version 1.4
TableB-4GLLDataFormat
Name Exam
p
le Units Descri
p
tion
Messa
g
e ID $GPGLL GLL
p
rotocol heade
r
Latitude 3723.2475 ddmm.mmmm
N
/S Indicato
r
n
N
=north or S=south
Lon
g
itude 12158.3416 dddmm.mmm
m
E/W Indicato
r
W E=east or W=wes
t
UTC Position 161229.487 hhmmss.sss
Status A A=data valid or V=data not valid
Checksu
m
*2C
<CR><LF> End of messa
g
e 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.
TableB-6Mode1
Value Description
M Manual-forced to operate in 2D or 3D mode
A 2Dautomatic-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:

ET-312
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Version 1.4
$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 Exam
p
le Descri
p
tio
n
Messa
g
e ID $GPGSV GSV
p
rotocol heade
r
N
umber of Messa
g
es12 Ran
g
e 1 to 3
Messa
g
e Numbe
r
11 Ran
g
e 1 to 3
Satellites in View 07
Satellite ID 07 Channel 1
(
Ran
g
e 1 to 32
)
Elevation 79 de
g
rees Channel 1
(
Maximum90
)
Azimuth 048 de
g
rees Channel 1
(
True
,
Ran
g
e 0 to 359
)
SNR
(
C/No
)
42 dBHz Ran
g
e 0 to 99
,
null when not trackin
g
……. …….
Satellite ID 27 Channel 4
(
Ran
g
e 1 to 32
)
Elevation 27 De
g
rees Channel 4
(
Maximum90
)
Azimuth 138 De
g
rees Channel 4
(
True
,
Ran
g
e 0 to 359
)
SNR
(
C/No
)
42 dBHz Ran
g
e 0 to 99
,
null when not trackin
g
Checksu
m
*71
<CR><LF> End of messa
g
e termination
Depending on the number of satellites tracked multiple messages of GSV data may be required.
RMC-Recommended Minimum Specific GNSS Data
Table B-10 contains the values for the following example:
$GPRMC,161229.487,A,3723.2475,N,12158.3416,W,0.13,309.62,120598,,*10
TableB-10RMCDataFormat
Name Exam
p
le Units Descri
p
tio
n
Messa
g
e ID $GPRMC RMC
p
rotocol heade
r
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
Lon
g
itude 12158.3416 dddmm.mmm
m
E/W Indicato
r
W E=east or W=wes
t
S
p
eed Over Ground 0.13 knots
Course Over Ground 309.62 de
g
rees True
Date 120598 ddmm
yy
Ma
g
netic Variation2de
g
rees E=east or W=wes
t
Checksu
m
*10
<CR><LF> End of messa
g
e termination
SiRF Technology Inc. does not support magnetic declination. All “course over ground” data are
geodetic WGS48 directions.

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Version 1.4
VTG-Course Over Ground and Ground Speed
$GPVTG,309.62,T,,M,0.13,N,0.2,K*6E
Name Exam
p
le Units Descri
p
tio
n
Messa
g
e ID $GPVTG VTG
p
rotocol heade
r
Course 309.62 de
g
rees Measured headin
g
Reference T True
Course de
g
rees Measured headin
g
Reference M Ma
g
netic
S
p
eed 0.13 knots Measured horizontal s
p
eed
Units
N
Knots
S
p
eed 0.2 Km/h
r
Measured horizontal s
p
eed
Units K Kilometers
p
er hou
r
Checksu
m
*6E
<CR><LF> End of messa
g
e termination
2.2 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 would be used to
switch the module back to SiRF Binary protocol mode where a more extensive command message set is
available. For example,to change navigation parameters. When a valid message is received,the 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

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<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
convertted to two ASCII characters (0-9,A-F) for transmission. The most
significant character is transmitted first.
**<CR><LF> : Hex 0D 0A
B). Navigation lnitialization ID：101 Parameters required for start
This command is used to initialize the module for a warm start, by providing current position （in X, Y, Z
coordinates）,clock offset, and time. This enables the receiver to search for the correct satellite signals at
the correct signal parameters. Correct initialization parameters will enable the receiver to acquire signals
more quickly, and thus, produce a faster navigational solution.
When a valid Navigation Initialization command is received, 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
<Y> Ycoordinateposition
INT32
<Z> Zcoordinateposition
INT32

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<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 will be used.
INT32
<TimeOf Week> GPS Time Of Week
UINT32
<WeekNo> GPS Week Number
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> bit mask
0×01=Data Valid warm/hotstarts=1
0×02=clear ephemeris warm start=1
0×04=clear memory. Cold start=1
UBYTE

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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 that is an input only serial port
used to receive
RTCM differential corrections.
Differential receivers may output corrections using different
communication parameters. The default
communication parameters for PORT B are 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 to
correctly decode the data. When a valid message is received, the parameters will be stored in
battery backed SRAM and then the receiver will restart using the saved parameters.
Format:
＄PSRF102,<Baud>,<DataBits>,<StopBits>,<Parity>*CKSUM<CR><LF>
<baud> 1200,2400,4800,9600,19200,38400
<DataBits> 8
<StopBits> 0,1

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Version 1.4
<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
This command is used to control the output of standard NMEA message GGA, GLL, GSA,
GSV
RMC, VTG. Using this command message, standard NMEA message may be polled once,
or setup for periodic output. Checksums may also be enabled or disabled depending
on the needs of the receiving program. NMEA message settings are saved in 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

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Version 1.4
＄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 lnitialization ID:104 Parameters required to start using Lat/Lon/Alt
This command is used to initialize the module for a warm start, by providing current position (in
Latitude, Longitude, Altitude coordinates), clock offset, and time. This enables the receiver
to search for the correct satellite signals at the correct signal parameters. Correct initialization
parameters will enable the receiver to acquire signals more quickly, and thus, will produce a
faster navigational soution.
When a valid LLANavigationInitialization command is received,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

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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. If
this is unavailable, a default value of 75000 for GSP1, 95000 for GSP1/LX
will be used.
INT32
<TimeOfWeek> GPS Time Of Week
UINT32
<WeekNo> GPS Week Number
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

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0×04=clear memory. Cold start=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 getting
commands accepted. Invalid commands will generate debug information that should
enable the user to determine the source of the command rejection. Common reasons for
input command rejection are invalid checksum or parameter out of specified range. 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