USGlobalsat ET-312 User Manual

ET-312

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: 886-2-8226-3799/ Fax: 886-2-8226-3899

E-mail : service@globalsat.com.tw

Website: www.globalsat.com.tw

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ET-312

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

Chipset SiRF GSC3f/LP

Frequency L1, 1575.42 MHz

Code C/A Code

GPS Receiver

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

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ET-312

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

Version 1.4

Maximum Altitude

Maximum Velocity

Maximum Acceleration

Update Rate 1 Hz

DGPS WAAS, EGNOS, MSAS

Datum WGS-84

I/O Pins 1 serial ports

Type 13-pin stamp holes

Dimensions 28 mm * 20 mm * 2.9 mm

Power Supply

Backup Voltage

Power Consumption

＜ 18,000 meter

＜ 515 meter/second

＜ 4G

Interface

Physical Characteristic

DC Characteristics

3.3Vdc ± 5%

2.0 ~ 3.6Vdc ± 10%

Acquisition: 60mA Tracking: 42mA

Environmental Range

Humidity Range 5% to 95% non-condensing

Operation Temperature

Storage Temperature

-30℃ to 85℃

-40℃ to 85℃

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ET-312

2. Technical Information

 Block Diagram

 Module Pin Assignment:

Version 1.4

M1

1

GND

2

RF

3

GND

4

GND

5

GND

6

GND

7

VIN

GPS Engine Board

BATTERY

GND GND

RX

GPIO1

13 12

11 10

TX

9 8

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. Ty pical 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

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ET-312

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 command s to the engine board from SiRFdemo software or from user written software.

12. GND Ground.

13. GND Ground.

Version 1.4

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 Application Circuit

ET-312

Version 1.4

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

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 Dimensions

ET-312

Version 1.4

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 Recommend Layout PAD

ET-312

Version 1.4

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ET-312

 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.

Temperature [℃]

240℃ Max.

10±1s

235±5℃.

200℃

Version 1.4

150±10℃

30±10s

90±30s

Time [sec.]

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ET-312

n

r

N

m

t

N

p

d

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 Example Units Descriptio

Message ID $GPGGA GGA protocol heade

UTC Time 161229.487 hhmmss.sss

Latitude 3723.2475 ddmm.mmmm

/S Indicator Longitude 12158.3416 dddmm.mmm E/W Indicator W E=east or W=wes Position Fix Indicator 1 See Table B-3 Satellites Used 07 Range 0 to 12 HDOP 1.0 Horizontal Dilution of Precision MSL Altitude1 9.0 meters Units M meters Geoid Separation1 meters Units M meters Age of Diff. Corr. second 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.

N=north or S=south

ull fields when DGPS is not used

Version 1.4

Table B-3 Position Fix Indicator

Va l ue D es c ri

0 Fix not available or invali

1 GPS SPS Mode, fix vali

2 Differential GPS, SPS Mode , fix vali

3 GPS PPS Mode, fix vali

tion

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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ET-312

p

r

N

m

t

Table B-4 GLL Data Format

Version 1.4

Name Exam Message ID $GPGLL GLL protocol heade Latitude 3723.2475 ddmm.mmmm

/S Indicator n N=north or S=south Longitude 12158.3416 dddmm.mmm E/W Indicator W E=east or W=wes UTC Position 161229.487 hhmmss.sss Status A A=data valid or V=data not valid Checksum *2C <CR><LF> End of message termination

le Units Description

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

Table B-5 GSA Data Format

Name Example Units Description

Message ID $GPGSA GSA protocol header Mode1 A See Table B-6 Mode2 3 See Table B-7 Satellite Used1 07 Sv on Channel 1 Satellite Used1 02 Sv on Channel 2 ….. Satellite Used1 Sv 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.

Table B-6 Mode1

Va l ue Description

M Manual-forced to operate in 2D or 3D mode A 2Dautomatic-allowed to automatically switch 2D/3D

Table B-7 Mode 2

Va l ue Description

1 Fix Not Available 2 2D 3 3D

GSV-GNSS Satellites in View

Table B-8 contains the values for the following example:

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ET-312

n

r

N

r

)

g

)

g

n

r

N

m

t

yy

t

$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

Table B-8 GSV Data Format

Name Example Descriptio

Message ID $GPGSV GSV protocol heade

umber of Messages1 2 Range 1 to 3 Message Numbe 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 359 SNR(C/No) 42 dBHz Range 0 to 99,null when not trackin ……. ……. Satellite ID 27 Channel 4 (Range 1 to 32 Elevation 27 Degrees Channel 4(Maximum90 Azimuth 138 Degrees Channel 4(True, Range 0 to 359 SNR(C/No) 42 dBHz Range 0 to 99,null when not trackin Checksum *71 <CR><LF> End of message termination

Depending on the number of satellites tracked multiple messages of GSV data may be required.

1

1 Range 1 to 3

Version 1.4

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

Table B-10 RMC Data Format

Name Example Units Descriptio

Message ID $GPRMC RMC protocol heade UTC Time 161229.487 hhmmss.sss Status A A=data valid or V=data not valid Latitude 3723.2475 ddmm.mmmm

/S Indicator Longitude 12158.3416 dddmm.mmm E/W Indicator W E=east or W=wes Speed Over Ground 0.13 knots Course Over Ground 309.62 degrees True Date 120598 ddmm Magnetic Variation2 degrees E=east or W=wes Checksum *10 <CR><LF> End of message termination SiRF Technology Inc. does not support magnetic declination. All “course over ground” data are

N=north or S=south

geodetic WGS48 directions.

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ET-312

n

r

g

N

r

p

r

VTG-Course Over Ground and Ground Speed

$GPVTG,309.62,T,,M,0.13,N,0.2,K*6E

Name Example Units Descriptio

Message ID $GPVTG VTG protocol heade Course 309.62 degrees Measured headin Reference T True Course degrees Measured headin Reference M Magnetic Speed 0.13 knots Measured horizontal speed Units Speed 0.2 Km/h Units K Kilometers Checksum *6E <CR><LF> End of message termination

Knots

Measured horizontal speed

er hou

Version 1.4

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

<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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ET-312

<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

Version 1.4

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> Y coordinate position

INT32

<Z> Z coordinate position

INT32

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ET-312

<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

Version 1.4

（ 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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ET-312

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

Version 1.4

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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ET-312

<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,

Version 1.4

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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ET-312

＄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

Version 1.4

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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ET-312

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

Version 1.4

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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ET-312

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

Version 1.4

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

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worldwide common grid system that may be translated into local coordinate systems or map datums.

(Local map datums are a best fit to the local shape of the earth and not valid worldwide.)

Examples:

Datum select TOKYO_MEAN

$PSRF106,178*32

ET-312

Version 1.4

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